974 0750 Onan MDJA To MDJF Marine Diesel Engine Service Manual (12 1985)

User Manual: 974-0750 Onan MDJA to MDJF Marine Diesel Engine Service Manual (12-1985)

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Page Count: 92

Service

Manual

MDJA

MDJB

MDJC

MDJE

MDJF

Marine Diesel

GenSet

Engines

974-0750

12-85

Printed

in

USA

Safety

Precautions

It is recommended that you read your engine manual and be-

come thoroughly acquainted with your equipment before you

start the engine.

[awnR"cl

This symbol is used throughout this

manual to warn

of

possible serious personal injury.

-1

This symbol refers

to

possible equip-

ment damage.

Fuels, electrical equipment, batteries, exhaust gases and mov-

ing parts present potential hazards that could result in serious,

personal injury. Take care in following these recommended pro-

cedures.

Safety Codes

All

local, state and federal codes should be consulted and

complied with.

This engine is not designed or intended for use in aircraft.

Any such use is at the owner's sole risk.

General

Provide appropriate fire extinguishers and install them in

convenient locations. Use an extinguisher rated ABC by

N

FPA.

Make sure that all fasteners on the engine are secure and

accurately torqued. Keep guards in position over fans,

driving belts, etc.

If

it

is necessary to make adjustments while the engine is

running, use extreme caution when close

to

hot exhausts,

moving parts, etc.

Protect Against Moving Parts

0

Do

not wear loose clothing in the vicinity of moving parts,

such as PTO shafts, flywheels, blowers, couplings, fans,

belts, etc.

Keep your hands away from moving parts.

Batteries

Before starting work on the engine, disconnect batteries

to

prevent inadvertent starting of the engine.

DO NOTSMOKE while servicing batteries. Lead acid bat-

teries give

off

a highly explosive hydrogen gas which can

be ignited by flame, electrical arcing or by smoking.

0

Verify battery polarity before connecting battery cables.

Connect negative cable last.

Fuel System

DO

NOT

fill

fuel tanks while engine is running.

DO

NOT smoke or use an open flame in the vicinity of the

engine or fuel tank. Internal combustion engine fuels are

highly flammable.

Fuel lines must be of steel piping, adequately secured,

and free from leaks. Piping at the engine should be ap-

proved flexible line.

Do

not use copper piping for flexible

lines as copper will work harden and become brittle

enough to break.

Be sure all fuel supplies have

a

positive

shutoff

valve.

#

Exhaust System

0

Exhaust products of any internal combustion engine are

toxic and can cause injury, or death if inhaled. All engine

applications, especially those within a confined area,

should be equipped with an exhaust system

to

discharge

gases to the outside atmosphere.

0

DO

NOT use exhaust gases to heat

a

compartment.

0

Make sure that your exhaust system is free of leaks. En-

sure that exhaust manifolds are secure and are not

warped by bolts unevenly torqued.

Exhaust Gas

Is

Deadly!

Exhaust gases contain carbon monoxide, a poisonous gas that

might cause unconsciousness and death. It is an odorless and

colorless gas formed during combustion of hydrocarbon fuels.

Symptoms of carbon monoxide poisoning are:

Dizziness

0

Vomiting

0

Headache

0

Muscular Twitching

0

Weakness and Sleepiness

If you experience any of these symptoms, get out into fresh air

immediately, shut down the unit and do not use until it has been

inspected.

The best protection against carbon monoxide inhalation is

proper installation and regular, frequent inspections of the com-

plete exhaust system.

If

you notice a change in the sound orap-

pearance of exhaust system, shut the unit down immediately

and have

it

inspected and repaired at once by a competent me-

chanic.

Cooling System

0

Throbbing in Temples

0

Coolants under pressure have a higher boiling point than

water. DO NOT open a radiator pressure cap when cool-

ant temperature is above

212

degrees F

(1

00

degrees C)

or while engine

is

running.

Keep The Unit And Surrounding Area Clean

0

Make sure that oily rags are not left on

or

near the engine.

Remove all unnecessary grease and oil from the unit. Ac-

cumulated grease and oil can cause overheating and

subsequent engine damage and present a potential fire

hazard.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Table

of

Contents

TITLE

General Information

....................................................

2

Specifications

.........................................................

3

Dimensions and Clearances

.............................................

4

Assembly Torques and Special

Tools

....................................

6

Service and Maintenance

...............................................

8

Cooling System

.......................................................

16

Fuel System

..........................................................

36

Governor System

.....................................................

60

Engine Troubleshooting

................................................

7

Exhaust System

.......................................................

14

OilSystem

...........................................................

62

Starting System

.......................................................

68

Engine Disassembly

...................................................

75

INCORRECT SERVICE

OR

REPLACEMENT

OF

PARTS MIGHT RESULT IN

SEVERE PERSONAL INJURY AND/OR EQUIPMENT DAMAGE

.

SERVICE

PERSONNEL MUST BE QUALIFIED TO PERFORM ELECTRICAL AND/OR

MECHANICAL SERVICE

.

.

1

Redistribution or publication of this document, 

by any means, is strictly prohibited.

General Information

INTRODUCTION

This manual deals with specific mechanical and elec-

trical information needed by engine mechanics for

troubleshooting, servicing, repairing, or overhauling

the engine.

Use the table of contents for a quick reference to the

separate engine system sections.

Use the separate Parts Catalogs available at the

dealer level, for parts identification and for establish-

ing their proper location on assemblies.

The

TROUBLESHOOTlNG

GUlDE

provides

a

quick

reference for locating and correcting engine trouble.

The illustrations and procedures presented in each

section apply to the engines listed on the cover. The

flywheel end of the engine is the front end,

so

right

and left sides are determined by viewing the engine

from the front.

The disassembly section contains major overhaul

procedures for step by step removal, disassembly,

inspection, repair and assembly of the engine

components.

If a major repair or an overhaul is necessary, a compe-

tent mechanic should either do the job or supervise

and check the work of the mechanic assigned to do

the job to ensure that all dimensions, clearances and

torque values are within the specified tolerances.

The wiring diagram shows how the electrical compo-

nents are interconnected.

A parts catalog (available at the dealer level) contains

detailed exploded views of each assembly and the

individual piece part nurnbersand their proper names

for ordering replacement parts.

Use only Genuine Onan replacement parts to ensure

quality and the best possible repair and overhaul

results. When ordering parts, always use

the

com-

plete Model and Spec number

in

addition to the Serial

number shown on the nameplate.

ENGINE MODEL REFERENCE

Identify your model by referring to the MODEL and

SPEC (specification)

NO.

as shown on the unit

nameplate. Always use this number and the engine

serial numberwhen making reference toyour engine.

How to interpret MODEL and SPEC

NO.

on generator

set engines.

1.

2.

3.

4.

12.OiDJC

-

f

/

7

f

1

2

34

Factory code for general identification purposes.

Specific TYPE, as follows.

R

-

REMOTE type. Electric starting. Optional

accessory equipment can be connected for

2

wire remote control

of

starting and stopping

E

-

ELECTRIC start type. Electric starting at

the

plant only.

Factory code for specific optional equipment

supplied.

Specification (Spec Letter). Advances with fac-

tory production modifications.

2

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Specifications

All

dimensions in

U.S.

customary units

of

measure (metric in parentheses) unless otherwise specified.

~~

UNIT

OF

SPECIFICATION MEASURE MDJA MDJB MDJC MDJE MDJF

Number of Cylinders

1

2

4

2

4

Diesel Fuel ASTM2-D ASTM2-D ASTM2-D ASTM2-D ASTM2-D

Bore in 3.25 3.25 3.25 3.50 3.50

(mm) (82.55) (82.55) (82.55) (88.9) (88.9)

Stroke

in

3.625 3.625 3.625 3.625 3.625

(mm)

(92.07) (92.07) (92.07) (92.07) (92.07)

Displacement cu in 30 60 120 70

140

litre

(0.5)

(0.98) (1 -9)

(1

-2) (2.3)

Compression Ratio 19 to

1

19

to

1 19to1 19to1 19to1

Firing Order 1-2-4-3 1-2-4-3

Crankshaft Rotation

Governor Variable Speed Mechanical Variable Speed Mechanical

Valve Clearance (Cold)

Spec

A-C

Begin

Spec

D

*

Intake in 0.020 0.010 0.01

5

0.01

1 0.01 7 0.01 7

(mm)

(0.51)

(0.25) (0.38) (0.28)

(0.43)

(0.43)

Exhaust

in

0.020

0.010

0.01

3

0.01

6 0.017 0.01 7

(mm)

(0.51)

(0.25) (0.33) (0.41)

(0.43)

(0.43j

.

Oil Filter Full

Flow

Full Flow Full Flow Full Flow Full Flow

Crankcase Capacity qt

3

3.5

.

6.5 3.5 6.5

(viewed from flywheel) Clockwise Clockwise Clockwise Clockwise Clockwise

with filter change (I

i

tre) (2.8) (3.3) (6.2) (3.3) (6.2)

3

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Dimensions and Clearances

All

clearances given

at

room temperature

of

70°F

(21

"C)

.

All

dimensions

in

inches (millimeters

in

parentheses) unless otherwise specified

.

CAMSHAFT

Bearing Journal Diameter. Front

.............................................

2.2500-2.2505 (57.1 50-57.1 63)

Bearing Journal Diameter. Center

(4

cylinder)

.................................

1.2580-1.2582 (31 -953-31.958)

Bearing Journal Diameter. Rear

.............................................

1.1

875-1.1880 (30.163-30.175)

Bearing Clearance Limit (Original)

..................................................

.0015-. 0030 (-038-.076)

Bearing Clearance Limit (Replacement)

.............................................

.0012.. 0049 (.030-.123)

End Play

..............................................................................

.007.. 039 (0.2-1.0)

Cam Tappet Diameter (Prior to Spec P)

.........................................

.747 5.7480 (18.987-18.999)

Cam Tappet Hole Diameter (Prior to Spec P)

...................................

.7507.. 7515 (19.068-19.088)

Cam Tappet Diameter (Begin Spec

P)

..........................................

.8725.. 8730 (22.162-22.174)

Cam Tappet Hole Diameter (Eegin Spec P)

.....................

:

...............

.8755.. 8765 (22.238-22.263)

Large Bore Diameter

.....................................................

2.1 871 -2.1 876 (55.5523-55.5650)

Small Bore Diameter

........................................................

1.043-1.045 (26.4922-26.543)

Large Bearing Bore to Small Bearing Bore

(Center-to-Center)

.....................................................

5.998-6.002

(1

52.3492-1 52.4508)

Connecting Rod End Play

.............................................................

.002.. 016 (.05-.41)

Bore Honed Diameter (MDJA. MDJB. MDJC)

.................................

3.2495-3.2505 (82.537-82.563)

Bore Honed Diameter (MDJE. MDJF)

........................................

3.4995-3.5005 (88.887-88.91 3)

Maximum Allowable Taper

.................................................................

0.005

(0.127)

Maximum Allowable Out-of-Round

..........................................................

0.001 (0.025)

Main Bearing Journal Diameter

(1

&

2

cylinder)

.................................

2.2437-2.2445 (56.99-57.01)

Main Bearing Journal Diameter

(4

cylinder) ...................................

2.2427-2.2435 (56.965-56.985)

Center Main Bearing Clearance

(4

cylinder)

.........................................

.0024.. 0052 (.061-.132)

Front and Rear Main Bearing Clearance (Original)

(4

cylinder)

.........................

.0030.. 0043 (.076-.109)

Main Bearing Clearance (Original)

(1

&

2

cylinder)

....................................

.002.. 0033 (.051-.084)

Connecting Rod Journal Diameter

...........................................

2.0597-2.0605 (52.31 6-52.337)

Rod

Bearing Clearance

............................................................

.001.. 0033 (.025-.084)

End Play

...........................................................................

.010.. 015 (.254-.381)

CONNECTING

RODS

CY

Ll

NDER

CRANKSHAFT

Front and Rear Main Bearing Clearance (Replacement)

(4

cylinder)

......................

.0024-. 0062 (.06-.16)

Main Bearing Clearance (Replacement)

(1

&

2

cylinder)

.................................

.0014-. 0052 (.04-.13)

PISTONS AND

RINGS

Clearance in Cylinder

Measure

90'

to pin. just below oil ring

Ring Groove Width

(Prior to Spec

P).

...............................................................

.0050..

0070 (.127-.178)

(Begin Spec

P)

.................................................................

.0055-.

0075 (.140-.191)

TOP

.........................................................................

.0970.. 0980 (2.464-2.489)

NO

.

2

........................................................................

.0965.. 0975 (2.451 -2.477)

NO

.

3

........................................................................

.0965-. 0975 (2.451-2.477)

NO

.

4

........................................................................

.1880.. 1897 (4.775-4.818)

Ring Gap

............................................................................

.010.. 020

(.25-51)

Clearance in Piston

.....................................................................

Thumb-push Fit

Connecting Rod Bushing Clearance

................................................

.0002.. 0007 (.005-.018)

Rotation

.............................................................................

Counterclockwise

Pinion Clearance

to

Pinion Stop (Solenoid Plunger Bottomed)

...........................

.070.. 120 (1.78-3.05)

Armature End Play

..................................................................

.005..

030 (.030-.760)

PISTON PIN

STARTING

MOTOR

(prestolite)

4

Redistribution or publication of this document, 

by any means, is strictly prohibited.

.

VALVE-INTAKE

Stem Diameter (Stem is tapered)

Center

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-3401 -.3411 (8.639-8.664)

**Face.

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Valve Face..

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Guide Clearance

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.0015-.003 (.038-.076)

Stem

D

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.3405-.3415 (8.649-8.674)

Guide Clearance

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-0030-.0050 (.076-.127)

Valve Face

.......................................................................................

45"

Length .

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1.781 2 (45.2424)

Outside Diameter

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.4690-.4695 (1 1.91 26-1 1.9253)

Inside Diameter (after reaming)

Exhaust . .

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.3445-.3455 (8.750-8.776)

In take

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.3425--3435 (8.700-8.725)

Cylinder Block Bore Diameter..

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.467-.468 (1 1.8618-11.8872)

Valve Seat Bore (Diameter)

VALVE-EXH AUST

VALVE GUIDE

VALVE SEATS

Intake

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1

S47-.1.548 (39.29-39.32)

Exhaust .

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1.361-1.362 (34.570-34.595)

Depth (from Cylinder Head Face) .

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43--439 (10.99-11.15)

Exhaust

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1.364-1.365 (34.6456-34.6710)

Intake

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1

-550-1 -551 (39.37-39.39)

Seat Width..

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.047-.062 (1.19-1.57)

Angle

.............................................................................................

45"

Available Insert Oversizes . . . .

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,002 (.0508)

.005

(.127)

-010

(.254)

.025 (.635)

Load-Valve Closed

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45-49

Ib

(200-218

N*)

Load-Valve Open (Prior to Spec P) .

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. .

.

.

. . .

. .

.

. . . .

.

.

. . .

.

.

.

.

.

.

.

.

.

83-93

Ib

(369-414

N*)

Load-Valve Open (Begin Spec P). . . .

.

.

. .

.

.

.

. . .

.

.

.

.

.

.

.

.

. .

.

.

.

. . .

.

.

.

.

. .

.

.

.

.

.

.

.

. . .

.

.

87-97

Ib

(388-432

N*)

Seat Outside Diameter

VALVE

SPRINGS

'Newton

-

Base unit

of

force.

"Measure intake valve

stem

at

points

indicated.

Valve Stem Diameter

(intake)

(75.2

mm)

1.18

IN

(30.0

mm)

5

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Assembly Torques

and

Special Tools

The assembly torques given here will assure proper

tightness without danger of stripping threads. If a

torque wrench is not available, estimate the degree of

tightness necessary

for

the stud, nut, or screw. Be

careful not to strip threads. Use only reasonable force

and a wrench of normal length.

Specially designed place bolts do not require a lock-

washer or gasket.

Do

not attempt to use

a

lockwasher

with these bolts; it will defeat their purpose. Check all

studs, nuts, and screws often and tighten as needed

to keep them from working loose.

SPECIAL

TOOLS

These tools are available from Onan to aid service and

repair work.

Diesel Nozzle Tester

.

.

.

.

.

.

.

. . . . .

.

.

. .

.

. .

.

.420-0184

Diesel Pintle Nozzle Cleaning

Tool

Set

(includes injection nozzle

centering tool) .

. .

.

.

. .

. . . .

.

.

. .

.

. .

. .

.

.

.

.

.420-0208

Driver, Center Camshaft Bearing

(RDJF only) .

. .

.

.

.

.

.

.

.

.

. .

. .

. .

.

. .

. .

.

. . .

.420-0254

Driver, Valve Seat .

.

.

.

.

.

.

.

. .

.

.

.

. . .

.

.

.

. . .

.

.420-0270

Oil Seal Guide and Driver.. . .

. . .

. . .

.

.

.

.

,

.

.420-0456

Nozzle Centering Sleeve. .

.

. . .

.

. . . .

.

.

.

.

.

.

.420-0321

Delivery Valve Test Fixture..

.

.

. .

.

.

.

.

.

. .

.

.

.420-0322

Combination Main and Cam

Bearing Driver . . . . . .

.

.

. .

.

.

.

. . .

.

.

. .

.

. .

.

.420-0326

Diesel Compression Tester . . . . .

.

.

.

.

.

.

.

.

.

.420-0283

Valve Spring Compressor Tool

.

.

.

. .

.

.

.

. .

.

.420-0119

Valve Seat Remover.

. .

.

.

.

.

.

.

. . .

.

.

.

.

.

.

. .

.

.420-0311

RECESS

UNDER

HEAD

A749

TORQUE

SPECIFICATIONS Ft.-Lb.

Nom

Center main bolt

(4

cylinder) . . .

97-102 (131-138)

Connecting rod bolt.. . .

. .

.

.

.

. .

.

27-29 (37-39)

Rocker-Box cover.

.

.

.

. .

. .

.

. .

. .

.

8-1

0

(1

1-1

4)

Cylinder head bolt

. .

.

.

.

. .

.

. .

.

.

.

44-46 (60-62)

Exhaust manifold nuts..

.

.

.

.

. .

.

.

13-15* (18-20)

Flywheel mounting screw.. .

.

.

.

.

65-70 (88-95)

Fuel pump mounting screws

.

.

.

.

15-20 (20-27)

Gear case cover

.

. .

.

.

. .

.

.

. .

.

.

.

.

18-20 (24-27)

Injection nozzle mounting

screws .

.

. .

.

. .

.

. . .

.

. .

. .

. .

.

.

.

.

20-21 (27-28)

Injection pump mounting

screws .

.

. .

.

.

.

. .

.

.

.

. .

.

.

. .

.

.

.

.

15-1

6 (20-22)

Intake manifold .

.

.

.

.

. .

.

. .

. .

.

.

.

.

13-15 (18-20)

Oil base mounting screws . .

.

. . .

45-50 (61 -68)

Oil filter

. .

.

.

.

.

. .

. .

. Hand tight plus

114

to

1/2

turn

Oil

pump mounting screws .

.

.

.

.

15-20

(20-27)

Rear bearing plate .

.

. .

.

. . .

.

.

.

. .

40-45 (54-61)

Rocker arm nut . . . . .

. .

. .

.

.

.

.

. .

.

4-lo** (5-13)

Rocker arm stud .

.

. .

.

.

.

. .

.

.

.

. .

.

35-40 (48-54)

Glow plug .

.

. .

. .

.

. . .

.

.

.

.

.

.

.

..

.

.

10-15 (18-20)

-

Exhaust nuts must be tightened evenly.

Flywheel Puller

.

. .

. .

. . . .

.

.

.

. .

. .

.

.

.

. .

.

. .

.

.420-0100

Crankshaft Gear Puller

.

.

.

.

.

.

. . .

.

. .

.

.

.

. . .

.420-0072

Crankshaft Gear Pulling Ring .

.

.

.

.

.

.

.

.

.

.

.420-0248

Tool

Catalog

.

. .

.

.

. . .

.

.

.

. . . .

.

. .

.

.

. .

.

.

.

.

.

.900-0019

*'

-This torque

is

due to friction betwen the threads only and

locks the nuts

in

place. Use the rocker arm nut

to

adjust valve

lash.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Engine

Troubleshooting

7

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Service and Maintenance

PRE-STARTING

Preparations for the initial and each additional start-

ing operation should includecareful checks of the oil,

fuel, cooling, and electrical systems.

Before engine is put in operation, check all compo-

nents for mechanical security. If an abnormal condi-

tion, defective part, or operating difficulty is detected,

repair or service as required. The engine should be

kept free of dust, dirt, and spilled oil or fuel. Be sure

proper operating procedure is followed.

Crankcase

Oil

Multi-grade oils (such as 5W-30) are recommended

for service in ambient temperatures of 32OF and

colder. On Onan

J

Diesel liquid cooled engines,

SAE

15W-40 or 20W-40 oils (CD/SE Service Designation)

may be used

in

an ambient temperature range of

15OF

(-10°C)

through

90°F

(32OC). Refer to the oil chart

below for recommended viscosity grades at various

temperature ambients.

Use oil with an

API

classification of CD/SE (all viscos-

ity grades) or

CC/SE

(grades

1OW-30,

1OW-40,

or

5W-30

only).

When adding oil between oil changes,

it

is preferable

to use the same brand, as various brands of oil may

not be compatible. Refer

to

Maintenance Schedule

for recommended

oil

change intervals and pro-

cedures.

Crankcase pressure could blow out

hot

oll

and cause seflous,burns.

Do

NOT

check oil while the engine

is

operating.

Recommended

Fuel

Use

ASTM

2-D or 1-D fuel with a minimum Cetane

number of

45*.

Number 2 diesel fuel gives the best

economy for most operating conditions; however,

use

ASTM

1-D

fuel during the following conditions:

1.

When ambient temperatures are below 32"

F

2. During long periods of light engine load; or no

(OOC);

load.

*NOTE

Fuels with Cetane numbers higherthan45 may beneeded

in higher altitudes or when extremely low ambient temperatures

are encountered to prevent misfires.

Use low sulfur content fuel having a pour point

(ability to filter) of at least

10°F

below the lowest

expected temperature. Keep the fuel clean and pro-

tected from adverse weather. Leave some room for

expansion when filling the fuel tank.

Due to theprecise tolerances ofdie-

sel injection systems, it

is

extremely

important the fuel be kept clean.

Dirt

in the system

can cause severe damage to both the injection pump

and the injection nozzles.

WORK TRANSFER PUMP

PRIMING LEVER UNTIL

FUEL FLOWS FROM

RETURN

LINE FITTING

OF INJECTION

PUMP.

FIGURE

1.

BLEED

FUEL

SYSTEM

If

the camshaft pump lobe is up, crank engine one revolution

to

permit hand priming. When finished, return priming lever inward

(disengaged position)

to

permit normal pump operation.

8

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Bleeding

Fuel

System

Bleed airfrom fuel system asfollows: Disconnectfuel

return

line,

Figure

1.

Operate hand priming lever on

fuel transfer pump until fuel flowing from fuel return

line is free of air bubbles. Then reconnect the fuel

return line.

Preheating for

60

seconds

is

recommended on all

DJ-Series Diesels at 55°F

(13°C)

or lower, and

30

seconds

for

temperatures above

55°F

(13OC).

Refer

to

Onan

Diesel

Starting

Guide,

for additional starting

guidelines.

Inhalation of exhaust gases might

result in serious personal injury or

death. Be sure deadly exhaust gas

is

piped outside

and away from windows, doors, or other inlets to

building.

Use of ether as a sfarfing aid might

i

cause an explosion resulting in

severe personal injury and engine damage.

Do

not

use ether as a starting aid; heat or compression or

heat

from

the glowplugs may cause asudden ignition

of the ether vapor.

1.

Engage PREHEAT switch for the time period

4

PRE-HEATING AND STARTING

b

p

WnRNlNGI

recommended below:

30

seconds if above

55"

F

(13" C)

-

60

seconds if below

55°F

(13°C).

2.

Engage START switch while continuing preheat.

3.

If engine fails to start in

15-20

seconds, repeat

Hold

until engine comes up to speed.

To

START

4.

5.

1,

n

PREHEAT COLD ENGINE PUSH PREHEAT SWITCH AND HOLD-

*

30

SECONDS IF ABOVE

55OF

(13°C);

60

SECONDS

IF

BELOW

55OF

(13'C).

NEVER PREHEAT MORE THAN

60

SECONDS.

steps

1

&

2.

Absence

of

blue

exhaust

smoke

dur-

ing cranking indicates

no

fuel being delivered.

Determine cause.

In

extreme cold

it

may

be necessary to maintain

preheating up to

2

minutes after the engine starts

to obtain firing

or

to smooth

out

all cylinders,

especially at no load

or

light loads.

Do

not

exceed the one minute

preheat periods to prevent heat-

er burn

out

and conserve the battery. Longer

preheating time prior

to

cranking the engine can

ruin the manifold heaterandglowplugs because

fhere

is

no

incoming air flow

io

cool them. Addi-

tional operation

of

the preheaters for a few

seconds during cranking in cold weather may

help

to

preheat the incoming combustion air and

prevent misfires as the engine

starts

running.

Verify that oil pressure gauge reads at least

20

psi

after engine reaches speed (pressure relief valve

is

not adjustable).

Do

not

apply overvoltage

to

the

starting circuit at any

time.

Overvoltage will destroy the glow plugs and air

heater.

If

jt becomes necessary

to

use an addi-

tional source of power

to

start the set, use a

72

volt baffery connected in parallel.

STOPPING

Push fuel solenoid switch40

Stop

position.

L.

Release switch when set stops.

If

stop circuit fails,

close fuel valve.

ONAN DIESEL STARTING GUIDE

-

INDUSTRIAL ENGINES

BEFORE

STARTING: CHECK FUEL SUPPLY.

BE SURE SHUTOFF VALVES ARE OPEN.

I

1

PRIME FUELSYSTEMIFFUEL FILTERS WEREDRAlNED

OR

CHANGED.

SYSTEM WAS JUST INSTALLED. FUEL TANK RAN

DRY.

1

1

i

1

-AIR HEATER

1

ELEMENT IN MANIFOL

TO PRIME FUEL

SYSTEM

MOVEPRIMING LEVERUP JECTION NOZZLE

AND

DOWN UNTIL FUEL

FLOWS STEADILY

FROM

RETURN

LINE (DISCON- LOW PLUG

NECTED). INJECTION PUMP

FUEL TRANSFER

PUMP

PRIMING

LEVER

-

FUEL FILTERS

FUEL RETURN LINE

-

I

~ ~~~

IF ENGINE FIRES BUT DOES NOTSTART. REPEAT ABOVE PROCEDURES, INCLUDING

PREHEAT. LIMIT CRANKING TO

15

TO

20

SECONDS TO CONSERVE BATTERY. IF

r

ENGINE STILL DOESNOTSTART. SEEYF ENGINE FAILS

TO

START" INFORMATION.

9

Redistribution or publication of this document, 

by any means, is strictly prohibited.

IF

ENGINE

FAILS

TO START=

IMPORTANT!

KEEP ENTIRE FUEL SYSTEM CLEAN AND FREE

FROM

WATER

DIESEL INJECTION PUMPS WILL FAIL

IF

SYSTEM CLEANLINESS

IS

NEGLECTED

INJECTION PUMPS AND NOZZLES ARE NOT FIELD REPAIRABLE

TEMPERATURES BELOW

32

F

(0

C): USE NUMBER

1

DIESEL FUEL. USE CORRECT VISCOSITY OIL.

KEEP BATTERIES FULLY CHARGED. DO NOT USE ETHER STARTING AID.

I

OBSERVE ENGINE EXHAUST”SM0KE SIGNALS”:

-

r

I

1

LUE-WHITE EXHAUST SMOKE LITTLE

OR

NO

EXHAUST

SMOKE

ENGINE

IS

NOT GETTING FUEL.

PRIME FUEL SYSTEM, OBSERVE FUEL FLOW FROM RETURN LINE.

ENGINE

IS

GETTING FUEL

CHECK PREHEAT SYSTEM:

1.

OBSERVE AIR HEATER

THRU AIR INLET.

2.

ENGAGE PREHEAT.

3. IF HEATER ELEMENT DOE:

NOT GLOW RED WITHIN

30

SECONDS. CHECK AIR

HEATERAND GLOW PLUG

WIRING.

CONNECTIONS TIGHT?

FREE FROM CORROSION?

~

8-79

98-4006

I

FUEL FLOWS STEADILY

I

LITTLE OR NO FUEL FLOW

I

I

SOLENOID ROD SHOULD

PULL IN AND THROTTLE ARM

FOLLOW (AS SHOWN) WHEN

START SWITCH

IS

TURNED

ON. IF NOT. CHECK FOR

G LINKAGE

OR

BROKEN WIRES

LENOID

ROD

THROTTLE

ARM

I

CHECK FUEL SUPPLY

SYSTEM:

FUEL TANK EMPTY?

SHUTOFF VALVES

FUEL LINES KINKED?

LOOSE CONNECTIONS?

CLOGGED FUEL FILTERS?

CLOSED?

1

I

I I

IF ENGINE

IS

STILL NOT GETTING FUEL. CHECK TRANSFER PUMP

1.

CRANK ENGINE AND OBSERVE FUEL FLOW FROM RETURN LINE.

2.

IF FUEL DOES NOT SPURT OUT, PUMP

MAY

BE DEFECTIVE.

IF ENGINE STILL DOES NOT START. CONTACT AUTHORIZED ONAN SERVICE REPRESENTATIVE

AUTOMATIC STARTING AND STOPPING

Optional controls may be used for automatic start

and stop, but must provide engine preheating.

The automatic control should have a time delay relay

to preheat glow plugs and the manifold heater for at

least

20

seconds before cranking occurs. The time

delay relay prevents immediate engagement of the

starter in case the load is reapplied before the engine

stops.

APPLYING LOAD

If practicable, allow engine to warm up before con-

necting a heavy load. Continuous overloading causes

high operating temperatures that can damage

the

engine. The exhaust system may form carbon depos-

its during operation at light loads; apply full load

occasionally before shut-down to prevent excessive

carbon accumulations.

Try to apply the load in steps instead of full load at

one time.

BREAK-IN

PROCEDURE

The unit should be run in the following sequence:

1.

One half hour at 112 load.

2. One half hour at

3/4

load.

3.

Full load.

Continuous running under one half load during the

first few hundred hours may result in poor piston ring

seating, causing higherthan normal oil consumption

and blowby.

Drain and replace the crankcase oil after

first

50

hours

of

opera-

tion; drain while the engine

is

still hot.

INSPECTION

Check for alignment of engine and load. Misalign-

ment will causeexcessive vibration and bearing wear.

Make a visual inspection of the entire installation.

Contact with rofafing rnachlnery

mighf cause serious personal injury

or

death. Stay clear

of

rofafing componenfs and

ensure fhaf profecfive shields and guards are in place

and secured before operafing machinery.

10

Redistribution or publication of this document, 

by any means, is strictly prohibited.

VENTlLATlON

Good ventilation is needed to cool the engine and to

support combustion.

Avoid

recirculation

of ventilat-

ing air.

lnhalafion

of

exhausf gases might

i

resulf in serious personal injury

or

death.

Do

not use exhaust heat to warm a

room,

compartment or storage area.

HOURS

OF

OPERATION

8

.

50

(more often

in

dusty

conditions)

100

200

500

600

2000

3000

5000

EXHAUST

Pipe exhaust gas outside any enclosure: exhaust gas

is poisonous. Exhaust pipes must not terminate near

inlet vents. Avoid sharp bends. Use sweeping, large-

radius elbows. Use a section of seamless, flexible

tubing between the engine and any rigid pipe to res-

trict vibration.

MAINTENANCE TASK

Inspect exhaust system

Inspect engine

Check fuel

supply,

see Note

1

Check oil level. See Figure

2.

Check air cleaner.

Clean governor linkage

Change crankcase oil

Drain fuel condensation traps

in

lines and filters,

see Note

1

Replace oil

filter

Check battery condition

Clean breather standpipes

0

Check start-disconnect circuit

Check valve clearances

Change primary fuel filter

Grind

valves

(if

required)

Clean holes

in

rocker box

Check nozzle spray pattern,

Change secondary fuel filter

General overhaul

(if

required)

oil line orifices

see Note

2

see Note

3

BATTERIES

Check the condition

of

the starting batteries at least

every two weeks. See that connections are clean and

tight.

A

light coating of non-conductive grease will

retard corrosion at terminals. Keep the electrolyte at

the proper level above the plates by adding distilled

water. Check specific gravity; recharge if below

1.260.

DUST AND DIRT

1.

Keep inlet screen free of dirt, etc.

2. Service air cleaner as frequently as necessary.

3.

Change crankcase oil every

50

operating hours.

4.

Keep oil and fuel in dust-tight containers.

5.

Keep governor linkage clean.

HIGH

ALTITUDE

Maximum power will be reduced approximately

4

percent for each

1000

feet (310 m) above sea level,

after the first 1000 feet (310

m).

1.

2.

3.

4.

LOW TEMPERATURES

Use correct SAE

No.

oil for temperature condi-

tions.

Change

oil

only when engine

is

warm. If an

unexpected temperature drop causes

an emer-

gency, move engine to a warm location or apply

heated air (never use open flame) externally until

oil

flows

freely.

Use fresh fuel. Protect against moisture conden-

sation.

.

Keep fuel system clean, and batteries in a well

charged condition.

Use additional preheat cycles during cold starts.

Do

not exceed one minute preheat

periods; longerperiods can

ruin

the

heater elements.

OPERATOR AND SERVICE MAINTENANCE SCHEDULE

NOTE

1.

Water or foreign material

in

fuel can

ruin

the injection

system.

If

daily inspection shows water

or

excessive

dirt

in

sediment bowl fuel, handling and storing facili-

ties should

be

checked and situation corrected. Prirn-

ary and secondary fuel filters must

be

replaced follow-

ing

correction of fuel contamination problem.

2.

Thisservice

must

beconducted by trained diesel injec-

tion equipment personnel with suitable test facilities.

Omit this service until these conditions can be met.

3.

Tighten head boltsand adjust valve clearanceafterfirst

50

hours on an overhauled engine.

'

11

Redistribution or publication of this document, 

by any means, is strictly prohibited.

OIL FILTER CHANGE

Place pan under old filter and remove by turning

counterclockwise. Clean filter mounting area. Lubri-

cate gasket on new filter with oil and screw filter on

clockwise until gasket touches mounting base, then

tighten

1/2

turn.

OIL DRAIN EXTENSION

For service convenience, install a short (less than

10

inches

[254

mrn]) oil drain extension made from

standard pipeand fittings, in the 1/2-inch

(12.70

mm)

pipe-tapped

oil

drain'hole in the base.

Crankcase pressure

could

blow

out

hot oil

and

cause serious burns.

Do

NOT

check

oil

while fhe engine

is

operating.

CRANKCASE

BREATHER

PIPE

INSERT A

SOFT

WIRE THROUGH

BREATHER PIPE

TO

CLEAN

BREATHER

SYSTEM

OIL LEVEL INDICATOR

FUEL

PUMP

FUEL TRANSFER

PUMP

BALL JOINT

DUAL FUEL FILTER SYSTEM

FIGURE

2.

MAINTENANCE PROCEDURES

12

Redistribution or publication of this document, 

by any means, is strictly prohibited.

OUT-OF-SERVICE

PROTECTION

The natural lubricating qualities of

No.

2

diesel fuel

should protect

a

diesel engine for at .least 30-days

when unit is not in service. To protect an engine that

will be out

of

service

for

more than

30

days, proceed

as follows: Derature.

Returning

a

Unit to Service

1.

Remove cover and all protective wrapping.

Re-

move

plug

from

exhaust

outlet.

2.

Check warning tag on oil base and verify that oil

viscosity is

still correct

for

existing ambient tem-

1.

2.

3.

4.

5.

6.

7.

8.

Run engine until thoroughly warm; under at least

50

percent load.

Shut down engine and drain oil base while still

warm. Refill and attach a warning tag indicating

viscosity of oil used.

Remove glow plugs. Pour l-ounce of rust inhibi-

tor (or

SAE

#10 oil) into each cylinder. Install

Crank engine by hand only to

distribute oil in cylinder. Starter

cranking

is

too fast; oil or inhibitor fluid will fire if

cranked with starter at normal room temperature.

Service air cleaner per

Maintenance

Schedule.

Clean throttle and governor linkage and protect

by wrapping with a clean cloth.

Plug exhaust outlets to prevent entrance of mois-

ture, bugs, dirt, etc.

Clean and wipeentire unit. Coat partssusceptible

to rust with a light coat of grease or oil.

Disconnect battery and follow standard battery

storage procedure.

glow plugs.

3.

Clean and check battery. Measure specific grav-

ity (1.260 at

77OF

[25O

C])

and verify level is at split

ring. If specific gravity is

low,

charge until correct

value

is

obtained. If level

is

low, add distilled

water and charge until specific gravity is correct.

DO

NOT

OVERCHARGE.

lgnifion

of

explosive battery

gases might cause severe per-

sonal

injury.

Do

not smoke while SeNiCing batter-

ies.

4.

Check that fuel injectors and fuel lines are secure

and correctly torqued.

5.

Clean heat exchanger.

6.

Connect batteries.

7.

Verify that no loads are connected to engine.

-1

Inhalation of exhaust gases

might result

in

serious personal

iniury

or deafh. Be sure deadly exhaust gas is

piped outside and away from windows, doors, or

other inlets

to

building.

8.

Start engine.

After engine

has

started, excessiveamount

of

bluesmokewill

be exhausted until the

rust

inhibitor

or

oil

has

burned away.

Accidental starting of the engine

might cause severe personal injury

or death. Disconnect

the

battery cable when repairs

are made

to

the engine, controls, or generator.

.

13

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Exhaust

System

'

Unitsof

Measurement

Inches

of

Water

Inches

of

Mercury

Ounces

GENERAL

The exhaust system must efficiently expel all engine

combustion products and muff

le

exhaust noises with

minimum back pressure. If back pressure is too high,

volumetric efficiency of the engine is reduced, fuel

economy drops, exhaust temperature increases, and

valve life is shortened.

Full

Load

27

2

15.6

02.

Back pressure must not exceed

27

inches

(686

mm)

of water column for the rated load when measured

with a manometer at the exhaust manifold, Figure

3.

FIGURE

3.

BACK

PRESSURE TEST WITH MANOMETER

EXHAUST SMOKE

A

light gray or light bluesmoke may bearesultof low

ambient temperature and light load. This smoke is

unburned fuel (not harmful to the engine) and disap-

pears when more load is applied.

Black smoke indicates overfueling (more fuel than

oxygen) and is usually caused by overloading. The

smoke or unburned fuel becomes carbon when

raised to a high temperature. Carbon contributes to

engine damage because it contaminates the iubricat-

ing

oil.

Inhalation of exhaust gases might

a

result

in

serious personal injury or

death.

Do

not use exhaust heat

to

warm a room,

compartment,

or

storage area.

WARNING

Vent exhaust gases outside. Use flexible tubing only

between the engine exhaust outlet and rigid piping.

Inhalation

of

exhausf gases might

result in serious personal injury or

death. Inspect exhaust system audibly and visually

for leaks dally. Repair any leaks immediately.

WATER

COOLED

EXHAUST

Marine exhaust systems are designed

so

that a

minimum mount of heat will be radiated from the

exhaust system components. This is done

to

keep the

heat b'uild-up

in

the engine compartment to a min-

imum. Exhaust heat is dissipated by using a water

cooled exhaust manifold and a water injected exhaust

pipe and muffler system. The exhaust manifold is

encased ina shell through which engine coolant or

sea water is circulated. Just beyond the exhaust

manifold,

a

special elbow (see Figure

4)

is fitted

which allows the output water from the sea water

system to be injected into the exhaust pipe. The

injected sea water is carried out thorugh the exhaust

system and discharged into

the

flotation water.

CONNECTED

TO

EXHAUST

MANIFOLD

.\

SEA

WATER

INPUT

EXHAUST

ELBOW

ASSEMBLY

APPLY

PIPE

TO

ALL

PIPE

TWO

HOSE

CLAMPS

HIGH

EXHAUST

TEMPERATURE

RUBBER

EXHAUST

SHUTDOWN

SWITCH

HOSE

EXS-1014

FIGURE

4.

EXHAUST ELBOW

14

Redistribution or publication of this document, 

by any means, is strictly prohibited.

.

Typical Installations

All

water injected exhaust systems must be designed

so

that

the

discharge water

will

not

flow

back

into

the

engine. There are several methods that can be used

to

keep water out of the engine.

All

are based on

injecting the water at a point

a

few inches approx-

imately

4

inches

(102

rnm)

below the exhaust mani-

fold outlet and installing a sharp drop

in

the exhaust

line that water cannot normally flow over. These

methods are divided into two general categories:

above water line and below water line installation.

Above

WaterLine: The exhaust manifold must be one

foot

or more above the load water line and the water

must be injected near the exhaust manifold. The

exhaust pipe is pitched downward

1/2

inch per foot

(13

mm

per

305

mm)

to

allow draining in the line

'

whether the genertor set is running

or

stopped.

Below Wafer Line: An Onan Aqualift muffler may be

used for below the water line installations if the lift

height is no greater than four feet (1220 mm).

A

siphon break is required when the water injection

elbow is below the water line (seeFigure5)

to prevent

water from being siphoned into theexhaust manifold.

The siphon break will be mounted at least

12

inches

(305

mm) above

the

load water line.

If the

lift

height is greaterthan four feet

(1220

mm), a

riser exhaust system will be used. The exhaust

system

will

run

in

a

loop above the water line to a

point

12

to

18

inches

(305

to 457 mm) above the boat

load water line. A water jacket encloses the loop and

the water

is

injected on the outlet side at a point four

inches

(102

mm)

above the bottom of the loop.

A

condensation

trap

is

usually

installed

atthe

bottom

of

the dry exhaust line seciton. Drain the trap at regular

intervals

to

remove condensation.

Generally, exhaust systems

should

be

as

short as

possible with a minimum number

of

bends. The

radius of any bend in the exhaust pipe should be at

least

5

times the diameter

of

the pipe. The

dry

sections of exhaust line should be either insulated or

water jacketed.

Be sure the slotted opening in

fbe

EEEEl

vacuum reiief valve is open to atmos-

pheric pressure. The siphon break wiii not function if

the relief valve slot

is

closed in any way.

11

Ik

HANGERSTRAPS

VACUUM

RELIEF

RUBBER

HOSE

ATER

OUTLET

HAUST

WATER

ECTION

ELBOW

EXHAUST

OUTLET

FIGURE 5.

SIPHON

BREAK

EXHAUST

GAS

1s

DEADLY!

Exhaust gases contain carbon monoxide, a poisonous gas that might cause

unconsciousness and death.

it

is an odorless and coiorless gas formed during

combustion

of

hydrocarbon fuels. Symptoms

of

carbon monoxide poisoning

are:

Dizziness Vomiting

Headache

Weakness and Sleepiness Muscular Twitching

'

Throbbing in Temples

if you experience any

of

these symptoms, get out into fresh air immediafeiy,

shut down the unit and do not use unfll

if

has been lnspected.

The best protection against carbon monoxide inhaiafion is proper installation

and regular, frequent inspections of the complete exhaust system. lfyou notice

a change in the sound or appearance

of

exhaust sysfem, shut

the

unlf down

immedlafeiy and have

It

inspected and repaired at once by a competent

mechanic.

15

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Cooling

System

INSPECTION

As a part of standard maintenance procedures, the

entire cooling system should be inspected for signs

of leakage and checked for worn components. In-

spect the water pump bearings, impeller (neoprene),

and seals for signs of wear, and check for correct

drive belt tension. Locate the source

of

any leaks and

correct as required. Inspect

the

zinc pencils on heat-

exchanger cooled engines, and note the amount of

deterioration. Refer to the appropriate section for

recommended service procedures.

As a final check, run the engine at full load and verify

that the engine can maintain an operating tempera-

ture of approximately 18OOF (82'C). An engine that

operates significantly above

or

below this value

should be tested for malfunctions.

IMPORTANCE

OF

REGULAR

MAINTENANCE

The entire cooling system, including the block and

radiator, heat exchanger,

or

keel cooler should be

cleaned and flushed out at least once a year. This is

especially important in cold weather conditions

or

when preparing the unit for extended storage (over

30

days). The cooling system can work efficiently

only when it is clean.

A

build-up of rust and scale

in

the cooling system will slow down heat absorption

and restrict water flow.

PRESSURE CAP

DRAIN

PLUG

DRAINING COOLING SYSTEM

Open all drains and hose connections where coolant

may be trapped when changing

the

antifreeze solu-

tion

or

when preparing a unit for storage in freezing

conditions. Open the fill vent valve when draining

heat-exhanger cooled engines. The following drain

plugs and hoses must be removed to drain the

cool-

ing system completely:

Contact with

hof

coolanf might

n

result in serious burns.

Do

not

bleed

hof,

pressurized coolant

from

a closed cooling

sysfem.

Engine

Block: J-Series-Remove drain plug on

left

front side of engine.

(See

Figure

6).

Wafer

Pumps

(All

Unifs);

Remove drain plug under

pump

or

loosen pump cover (Figure

6).

Exhaust Manifold:

Remove plug from underside of

exhaust manifold (Figure

6).

Expansion Tank:

Remove plug from front side of

expansion tank (Figure

6).

Heat Exchanger (Draining Raw Water or Sea Wafer):

Removedrain plug from underside, loosen end cover,

or

loosen and remove hose to drain heat exchanger.

TankHeafer:

Loosen and remove lower hose to drain

tank heater.

Aqualiff Muffler;

The Aqualift muffler

has

relatively

little water in it during normal operation and does not

have to be drained during freezing weather.

Replace and tighten all plugs, fittings, and clamps

when draining is finished.

t

L

DRAIN

BLOCK

HERE

(SOME

MODELS

HAVE

A

PIPE

PLUG)

EXHAUST

MANIFOLD

J-SERIES

BLOCK

FIGURE

6.

DRAINING COOLING

SYSTEM

REMOVEPUMP

COVER

TO

DRAIN

WATER

PUMP

Redistribution or publication of this document, 

by any means, is strictly prohibited.

UNIT

MDJA

MDJB

MDJC

MDJE

MDJF

CLEANING AND FLUSHING THE

COOLING

SYSTEM

To clean rust and scale deposits from captive water

systems, drain the system (as previously described),

and then fill with clean water and cleaner solution.

Use an approved chemical cleaner (such as the type

used for cleaning automotive cooling systems), and

follow

the instructions provided by the supplier.

Chemical cleaners cannot be used

with

direct sea water cooled

marine engines.

WARNING

Cleaning solutions fypicallyconfain

i

strong chemicals that may cause

injury

if

used improperly. Read all warning labels

before using.

When cleaning

is

complete, drain the cleaning solu-

tion and flush the system. For best results the engine

and heat exchanger should be reverse-flushed. Allow

the engine to cool as much as possible before flush-

ing with cold water.

Never pour cold wafer info

a

hot

D

engine. Doing

so

may crack fhe

head or fhe cylinder block.

Do

not

operate engine

without

coolant

for

even a

few

minutes.

CAPACITY IN QUARTS

ENGINE

AND

HEAT

EXCH.

4.5

(4.3

L)

9.5 (9

L)

4.5

(4.3

L)

9.5

(9

L)

2.3

(2

L)

Flush system if engine operation indicates clogged

passages or overheating.

To flush the engine:

1.

Drain heat exchanger, cylinder block and exhaust

2,

3.

4.

5.

6.

To

1.

2.

3.

manifold. Removethermostats.

Remove the inlet and outlet hoses between the

engine and heat exchanger.

Close all drain plugs and attach the flushing gun

nozzle to the water outlet, as near the exhaust

manifold as practical. Restrict the normal inlet

line opening until the system fills with water, then

apply air pressure gradually. Repeat the process

until the flow of water from the cylinder block is

clean.

Remove flushing gun.

Reinstall thermostats, hoses, and drain plugs and

refill the system with the proper coolant.

When

flushing

is

completed, check the system

thoroughly for any leaks uncovered by the clean-

ing operations.

flush heat exchanger:

Flush the engine water jacket as previously dis-

cussed.

First remove water outlet hose between engine

water jacket to the heat exchanger.

Flush both fresh water side and raw water side of

heat exchanger.

4.

5.

6.

Remove

rubber impeller pump covertoflush raw

water side.

Flush

the

water-cooled exhaust manifold.

When flushing is. completed, check the system

thoroughly for leaks.

FILLING COOLING SYSTEM

All closed or captive water cooling systems should be

filled with

50/50

mixture of antifreeze and clean

water. This is the amount recommended for satisfac-

tory corrosion protection and boil-over protection.

In extremely low temperatures

(-25OF

or lower),

it

may be necessary to increase the percentage of

antifreeze to provide adequate protection against

freezing. Follow the recommendation of the supplier

to determine the amount of antifreeze needed for the

lowesttemperature expected. The antifreeze solution

must be able to protect the cooling system during the

coldest winter weather. Table

1

shows the capacities

of the various cooling systems.

TABLE

1.

COOLING

SYSTEM

CAPACTIES

Heat

Exchanger Filling

Improper filling of the heat exchanger (Figure

7)

can

cause overheating of

the

engine-To prevent this pos-

sibility, follow these instructions whenever adding

coolant to the heat exchanger:

1.

2.

3.

4.

5.

6.

7.

8.

9.

Remove fill cap.

Open fill vent valve (turn counterclockwise).

Remove vent plug (older city water cooled units

only).

Fill with coolant until vents begin to overflow.

Close fill vent valve (turn clockwise).

Replace vent plug (older city water cooled units

only).

Replace fill cap (prime pump on marine units).

Operate unit

10

minutes at full load; watch for

leaks.

Shut down unit.

17

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by any means, is strictly prohibited.

Contact With hot coolant might

result in serious burns.

Do

not bleed

hot,

pressurized coolant

from

a

closed cooling

system.

10.

Slowly open pressure cap and check water level.

11.

Fill system to top with coolant.

WATER

MANIFOLD FILL

VENT

VALVE

_,

I

t

8378

1

HEAT

EXCHANGER

FIGURE

7.

HEAT

EXCHANGER

FILLING

MARINE

COOLING

SYSTEMS

Three types of marine cooling systems are in general

use today: direct sea water cooling, heat exchanger

cooling, and keel or skin cooling.

Direct sea water cooling systems use an engine

mounted pump to draw flotation water and pump

it

through the engine and out through the exhaust sys-

tem. The floatation or sea water comes in direct con-

tact with the engine water jacket.

INLET FOR

COOLING WATER

FLUSH

i

HULL

The heat exchanger and keel cooling systems were

developed to keep sea water, and the resulting

sediment deposits (salt, silt, etc.), from the engine

cooling jacket. Both systems have a fixed quantity of

captive water in a closed system to cool the engine.

Sea water cools the captive water in the heat

exchanger or keel cooler. Sea water and captive

water are kept separated,

so

the engine water jacket

stays clean. Figure

8

shows a typical marine heat

exchanger.

Because marine generator sets operate typically in

very small compartments,

it

is important that the heat

radiated from the exhaust system be kept to

a

min-

imum.

To

accomplish this, the heated sea water is

usually discharged through the exhaust system.

Special mufflers, pumps, and anti-siphon devices are

required to avoid interference with the passage

of

exhaust gases and to prevent entry of water into the

combustion chamber.

Direct

Cooling

System

Onan engine generator sets constructed for direct

sea water cooling are equipped with a sea water

pump and are normally installed with a water filter,

water inlet valve (sea cock), and strainer.

A

through-the-hull flush-type fitting

is

used for a

water inlet. Heated sea water flows past the thermo-

stat to the exhaust manifold (water cooled) and is

discharged through the exhaust system. The dis-

charged water

cools

the entire exhaust system and

greatly reduces the amount of heat that would

normally radiate from the muffler and exhaust pipe

(see Figure

9).

Although this system is the simplest

and has the lowest initial cost,

it

is not recommended

for salt water or water that contains silt and debris.

WATER TO

EXHAUST LINE

FLEXIBLE

SECTION

LING WATER IN

Y

F

STRAINER

--

PITCH

t

DOWN

TO

MUFFLER

FIGURE

8.

HEAT EXCHANGER FIGURE

9.

DIRECT SEA WATER COOLING

18

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SIPHON

BREAK

ADAPTER

THERMOSTAT

F,LL

HOUSING

WATER

MANIFOLD

&-

RUBBER

HOSE

EXHAUST WATER

DISCHARGE

FRESH

WATER

\

FRONT

CYLINDER

BLOCK

CONNECTION

I

INCLOSEDSYSTEM

I

I

INLET

-

SEA

WATER

CENTRIFUGAL

PUMP

(FRESH

WATER)

FIGURE

10.

HEAT EXCHANGER COOLING

Heat Exchanger Cooling System

Marine heat exchanger cooling systems work using

the same principle as city water heat exchanger

sys-

tems.

Cool

water from an unlimited source (flotation

water) is circulated by the sea water pump through a

set

of

tubes encased within a surrounding shell (Fig-

ure

10).

Engine coolant is circulated through theshell

but is not mixed with the sea water. A second water

pump is used to circulate the engine coolant

in

the

captive system. The sea water passing through the

heat exchanger tubes absorbs the heat from the

engine coolant. The heated sea water is discharged

through the exhaust system. Figure

10

shows a

schematic of atypical marine heat exchanger cooling

system.

Keel Cooling System (Or Skin Cooling)

Keel coolers arecomprised of aseriesof finned tubes

through which heated engine coolant is circulated.

The keel cooler is attached to the underside of the

boat (keel)

so

that flotation water can pass between

the fins. the heat from

the

engine coolant is trans-

ferred to the finned tubes and absorbed by

the

flotation water. Keel coolers function similar to

.radiators except that the heat is dissipated to the

flotation water instead of to the air. An engine'driven

pump is used to circulate the coolant through the

water jacket and cylinder heads to the keel cooler.

A second pump is sometimes used to draw flotation

water and discharge

it

through the exhaust system.

This cools the muffler and exhaust pipe and reduces

the amount of heat radiated from these components.

As

with heat exchanger systems, the sea water

is

never mixed with the engine coolant. Figure1 1 shows

a schematic of a keel cooler system.

Skin coolers function similar to keel coolers except

that a section of the hull with an extra skin is used to

dissipate the heat. Engine coolant passes between

the hull of the boat and the exterior skin. The heat is

transferred to the skin and absorbed by the flotation

water. The remainder of the system operates the

same as a keel cooler system.

Keel coolers must be designed to provide adequate

cooling when thewater flowing through thefins is at a

minimum and

the

temperature of the flotation water is

at its maximum. This is necessary because theengine

is often required to operate

at

its heaviest load when

the boat is not moving. For

this

reason a larger

keel

cooler is required for the generator set than would be

required for a propulsion engine of equal size.

19

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NS ION

TANK

ENGINE

EXHAUST

MAN

I

FO

LD

EXHAlJST

LINE

FIGURE

11.

KEEL COOLER

WATER

FLOW

During normal operation, marine cooling systems

intake a greater amount of dirt and sediment than

would beexpected with radiator or city water cooling

systems. This contributes greatly to water pump wear

and increases the chances that water passages will

become clogged or restricted.

It

is important with

marine cooling systems that the water flow be

checked frequently to insure that adequatecooling is

maintained.

Sea

Water

All marine cooling systems (except keel coolers with

dry stack exhaust) require a continuous flow of

sea

water for adequate cooling. Anything that reduces or

blocks the flow of water in the sea water system may

cause overheating. Remove the filter screen (Figure

12)

from the water filter on a periodic basis and clean

away any accumulations of dirt and sediment. Flush

clean water through the screen before replacing the

filter. Also, check all hoses and pipes to make sure

there are no kinks or bends that could restrict water

flow.

When the boat is dry docked, the water inlet strainer

(located on outside of hull) should also be checked

for accumulations of debris and cleaned if necessary.

The water inlet should not be directly

in

line with

other water inlets as this could reduce the amount of

water received bythe unit when the boat is underway.

If

more than one inlet is present, they should

be

staggered.

RECOMMENDED FLUSH TYPE THRU-HULL

FITTING AND WATER FILLER

TO

ELECTRIC PLANT

FLUSH THRU-HULL

FlTT ING

WARNING.

DO

NOT USE SCOOP TYPE WATER

INLET FITTINGS ON ELECTRIC PLANTS USING

AQUALIFT MUFFLER SYSTEMS.

FIGURE

12.

TYPICAL MARINE WATER FILTER

DO

not use a scoop-type wafer inlet

lzz3

fiffing. When the boat

is

underway

and fhe generafor sef

is

not running, sufficienf ram

pressure can force wafer past the sea wafer pump,

flooding the exhaust system, and possibly flooding

the

engine cylinders.

Beforestarting operation, theseawater pump should

be primed and checked for water flow. The punp is

primed by removing a priming plug on the top of the

pump (not necessary with metal impeller pumps) or

by removing the outlet hose from the pump con-

nection. Fill the pump and hose with water and

replace the components. With the set running, check

theexhaust outlet to verify that the pump is delivering

water. An insufficient flow

of

water indicates that

there are obstructions in the system, the water pump

belt is loose, or the water pump is faulty. Inspect and

replace any hoses or pipes that have become re-

stricted or blocked. Refer to the section on

Water

Pumps

for water pump service procedures.

The minimum water flow requirements (in

GPM)

for

sea water systems are given inTable2. If necessary, a

test can be made to determine if the water flow is

adequate. Run the engine and use a pail to catch the

water that is discharged at the outlet connection on

the exhaust elbow during a

15

second period. Mea-

sure the number

of

gallons collected and multiply

that amount times

4

to obtain the flow rate in gallons

per minute. Compare with theamount shown inTable

2

to determine if the flow rate is sufficient.

Do nof run the generator set for

Ex3

more fhan one minute if the cooling

sysfem

is

fauify. Doing

so

can resuif in damage

to

water-cooled exhaust sysfem componenfs

as

well as

to the engine.

CAUT,ON

L

20

Redistribution or publication of this document, 

by any means, is strictly prohibited.

TABLE

2.

COOLING REQUIREMENTS

MODEL

3.0MDJA

6.OMDJB

7.5MDJE

12.OMDJC

15.OMDJF

MINIMUM

ENGINE WATER

Direct

*kW

Cooling

RATING (Sea

(MARINE

.

Water

DUTY) System)

3,000 3.4

6,000

3.8

7,500 3.8

12,000

4.0

15,000

4.0

Exchanger

or

Keel

Cooler

(Sea Water

3.66

I

3.0

3.0

4.7

4.7

HEAT

EXCHANGER

COOLING

AVAILABLE

FROM

ONAN

YES

YES

YES

YES

YES

COOLING

SYSTEM

CAPACITY (PT)

WITH

HEAT

EXCHANGER

4.5

9

9

19

19

Test

at

full

load

Captive Water

A second pump (metal impeller type) is required for

the captive water system on engines that have heat

exchangers or keel coolers. This pump circulates

enginecoolant continuously through the waterjacket

to the heat exchanger

or

keel cooler. Check all hoses

for kinks or bends that could restrict the water flow

and correct as required.

CONNECTED

\

.

SEA

WATER

7~_

1

INPUT

TO

EXHAUST

MANIFOLD

APPLY

PIPE

TO

ALL PIPE

HIGH EXHAUST

TEMPERATURE

EXHAUST

ELBOW

'ASSEMBLY

\\

EXS-1014

FIGURE

13.

EXHAUST

ELBOW

WATER

COOLED

EXHAUST

Marine exhaust systems are designed

so

that a

minimum amount of heat will be radiated from the

exhaust system components. This is done to keep the

heat build-up

in

the engine compartment to a mini-

mum. Exhaust heat is dissipated by using a water

cooled exhaust manifold and a water injected exhaust

pipe and muffler system. The exhaust manifold is

encased

in

a shell through which engine coolant or

sea water is circulated. Just beyond the exhaust

manifold, a special elbow (see Figure

13)

is fitted

which allows the output water from the sea water

system to be injected into the exhaust pipe. The

injected sea water is carried out through the exhaust

system and discharged.

Typical Installations

All water injected exhaust systems must be designed

so

that the discharge water will not flow back into the

engine. There are several methods that can be used

to keep water out

of

the engine.

All

are based on

injecting the water at a point a few inches (approxi-

mately4

[lo2

mrn])

belowtheexhaust manifold outlet

and installing a sharp

drop

in

the exhaust line that

water cannot normally flow over.

21

Redistribution or publication of this document, 

by any means, is strictly prohibited.

SIPHON BREAK

A

siphon break is used with

all

marine installations

where the exhaust water injection elbow is

BELOW

the load water line. The siphon break (see Figure

14)

is

a vacuum operated vent valve that opens the

exhaust water discharge line to the atmosphere when

the engine shuts down. The open valve prevents

flotation water from being siphoned into the exhaust

manifold. The siphon break is mounted no less than

12

inches

(305

mm) above the water line. If space is

limited it may be remotely mounted but must be

within

5

feet more than

(1.5

m)

of

the exhaust water

injection elbow. In all installations the siphon break

must be mounted vertically with the threaded end

pointing down.

Be

sure fhe slofted opening in fhe

vacuum relief valve

is

open

to

af-

mospheric pressure. The siphon break will

nof

func-

fion

if

the relief valve

slof

is

closed in any way.

HANGER

STRAPS

RUBBER

HOSE

WATER

OUTLET

XHAUST

WATER

JECTION

ELBOW

-

EXHAUST

OUTLET

FIGURE

14.

SIPHON BREAK

HEAT EXCHANGERS

Several types

of

heat exchangersare currently

in

use

with marinecooling systems.Thefront mount typeof

heat exchanger shown in Figure

15

is used with the

MDJA and MDJB and was used with earlier models of

the MDJE, and MDJF.

It

is

mountedat the front

of

the

engine perpendicular to the engine center line. The

end caps are removable for cleaning and a separate

expansion tank

is

required. The sea water side

of

these heat exchangers

is

protected from corrosion

with either one

or

two zinc pencils (mounted on pipe

plugs) that are placed in one end of the heat

exchanger.

FIGURE

15.

FRONT MOUNT HEAT EXCHANGER

The side mount type of heat exchanger shown in

Figure

16

is used with later models of the MDJC,

MDJE, and MDJF. It is mounted on the side of the

engine

just

above the exhaust manifold.The end caps

are removable

for

cleaning and the expansion tank is

incorporated with theoutside shell. On some models,

the sea water side of the heat exchanger is protected

from corrosion with azinc pencil located close to the

sea water inlet. Other models may not have zinc

pencils.

AIR

BLEEDER

VALVE

HEAT

EXCHAN

CENTRIFUGAL EXHAUST

AND

PUMP

RAW

WATER

DISCHARGE

FIGURE

16.

SIDE MOUNT HEAT EXCHANGER

Sea Water Side

Remove and inspect thezinc pencils that are used for

corrosion protection every two months. Replace if

the pencils are deteriorated to less than one half their

original size.

22

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by any means, is strictly prohibited.

The sea water side of the heat exchanger should be

inspected and cleaned on a yearly basis. Remove the

two end caps and flush out any deposits that may

have accumulated in the tubes. Be certain to note the

position of the gaskets when removing the heat

exchanger ends. On some models the gaskets direct

the water flow and when replaced must be positioned

the same way they were when removed.

Captive

Water

Side

The captive water side of the heat exchanger should

be protected from corrosion and scale formation by

filling theenginecooling system with

a50/50

mixture

of antifreeze and water. If not protected, rust and

scale will form on the walls of the engine water jacket.

The rust and scale will combine to form an insulation

layer on the water jacket which will reduce the

efficiency of heat transfer to coolant.This can lead to

overheating and subsequent damage to the engine.

Rusty water or rusty solutions of antifreeze indicate

the formation of rust on the water jacket. If this is the

case, the engine water jacket and heat exchanger

should be cleaned and thoroughly flushed out, as

described

in

the

MAlNTENANCf

section. Use a

chemical cleaner to remove rust and scale deposits,

following the procedure recommended by the sup-

plier.

KEEL COOLERS

Keel cooling

(see

Figure

17)

is available as an option

on the

MDJA, MDJB,

MDJC, MDJE, and

MDJF

generator sets. The captive water pump, mounting

bracket, belt guard, hose, and fittings are supplied by

Onan. Somesetsmay also haveasea water pump for

injecting water into the exhaust system, while other

sets may use a

dry

stack exhaust. The keel cooler,

expansion tank, and plumbing must be supplied by

customer.

The keel cooler should be protected from corrosion

and scale formation by filling the engine cooling

system with a

50/50

mixture of antifreeze and water.

Follow the same service procedures recommended

for the captive water side of heat exchangers (see

previous section) to remove rust or scale formations.

With some keel cooler systems, a sea water pump

is

used for injecting water into the exhaust system.

Check the water filter after every

100

hours of

operation. Change sooner if the unit is used under

exceptionally dirty water conditions. When the boat

is dry docked, inspect the keel cooler and remove any

accumulation of sediment or debris.

TANK

-

EXPANSION

FIGURE

17.

KEEL

COOLER INSTALLATION

23

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MARINE WATER PUMPS

Two types of marine water pumps are in general use:

the metal impeller pump and

the

neoprene impeller

pump. Each pump has certain advantages and dis-

advantages (see Table

3)

and both are used exten-

sively with marine cooling systems. Two types of

pumps are necessary because water pumps are used

to perform different functions, depending on the type

of cooling system and the operating conditions.

Metal impeller pumps provide no suction lift but can

operate in hot, cold, or dirty water. Neoprene impeller

pumps provide a suction

lift,

but can be used only

with clean, cool water.

The metal impeller pumps are used for captive water

systems, and the neoprene impeller pumps are used

for sea water systems.

All

captive water system

pumps (metal impeller) are driven by

a

V-belt from

the engine crankchaft.

All

sea water pumps (neo-

prene impeller) for the J-series (except

MDJE,

Spec

AB)

are gear driven.

Captive Water Pump

Periodically check the captive water pump forwear or

signsof leakage from theshaft seal. Loosen thedrive

belt and move the water pump pulley back and forth.

The pulley should be tight on the shaft and

only

a

slight amount of bearing play should be felt. Rebuild

the pump if wear is excessive or if the seal leaks. Refer

to the section on

Water

Pumps

for water pumps

service procedures.

Sea Water

Pump

Periodically check the sea water pump for signs of

leakage from the shaft seal.

A

leaking shaft seal may

allow water to enter the crankcase and contaminate

the engine oil. Remove the pump end cover (see

Figure

18)

and inspect the impeller for cracking or

signs

of

wear. The impeller deteriorates with time

because of continuous flexing and must be period-

ically replaced. If the impeller fails, check for pock

marks on its end surfaces. This indicates that air has

been entering cooling system, reducing pump lubri-

cation and causing overheating. Check all hose

connections for leaks that could admit air, and

tighten

as

required. If

the

impeller fails after short

service (under500 hours),

checkforpossibledefects.

If impeller blades have broken, locate and remove the

particles or they will impede water flow. When re-

installing, coat the impeller with grease, and make

certain the impeller cover is air-tight. Tighten the

cover screws to 15-17 inch-pounds (1.70-1.92 Nm).

Refer to the section on

Water

Pumps

for water pump

service procedures.

FIGURE

18.

END

COVER

REMOVAL

WATER PUMP REPAIR

This section covers removal, repair, and installation

procedures for all metal impeller and neoprene

impeller water pumps used with Onan marine liquid-

cooled engines. Repair Kits are available for most

water pumps. Table

3

shows the water pumps used

with Onan marine liquid-cooled engines. Metal

impeller pumps are required for circulating HOT

engine coolant. They are most commonly used with

marine cooling systems that use a heat exchanger.

Neoprene impeller pumps may be used only for

pumping COOL water because the impeller deterio-

rates rapidly

in

hot water. They are most commonly

used for pumping sea water in marine cooling

systems.

24

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TABLE

3.

WATER

PUMPS

132-01 10

With Heat Exchanger

MDJA (Also

for

Keel

Cooler Models)

MDJB

MDJC

MDJE

MDJF

132-0074

With Keel Cooler

MDJB

MDJC

MDJE

MDJF

131

-0257

131 -01

52

132-01 15

MDJE MDJA Begin Spec E

MDJC

Spec

S

Begin MDJB Begin Spec

L

w/heat exchanger

Spec AB MDJC Begin Spec D MDJF before

1976

wlo heat exchanger wlheat exchanger

Spec

D-R

with

heat exchanger

MDJE Spec A-AA

MDJF wlo heat

exchanger

132-0059

132-01

47

MDJF Begin

1976

with heat

exchanger

MDJA Spec

MDJB Spec

MDJC Spec

A-D

A-K

A-C

BODY DRAIN IMPELLER

LOCKING

BOLT COVER

I

PLUG

I

SCREW

SHAFT

AND BEARING

I'

'

SEAL

1

COVER

GASKET

SEAT

FIGURE

19.

PUMPS

#132-0110

AND

M32-0074

25

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WATER

PUMPS

#132-0110

and

#132-0074

Pumps #132-0110 and #132-0074 are centrifugal

pumps with metal impellers (Figure 19).

Disassembly

1.

2.

3.

4.

Remove the water inlet fitting, drive belt pulley,

cover screws, and pump cover gasket.

Unscrew the threaded impeller from the pump

shaft by turning the impeller

in

a counterclock-

wise direction (when facing impeller).

Slide the seal seat, wear face, and bellows

assembly

off

the shaft. Loosen the clamp screw

and slide the pump body

off

the pedestal.

Remove the bearing lock ring and drive the shaft

and bearing assembly out of the pedestal. The

bearing is press fit on the shaft and comes

off

in

one integral part. The bearing is packed with

a

lifelong lubricant and is sealed at each end.

Assembly

i

Replace all worn components such as bearings,

seals, wear face, and impeller and use a new cover

gasket. Assembly sequence is the reverse of the dis-

assembly procedure.

FIGURE

20.

WATER

PUMP

CLEARANCES

Centering

Pump

Body

After the pump has been assembled (see Figure

20),

the impeller

(B)

must be centered in

the

body cover

space(C-C). Adjustment ismade by moving the pump

body fore and aft until the shaft can be rotated freely

by hand, without binding.The pump must beadjusted

with the drive belt

off.

If not centered properly, the

impeller

will

rub on the body or cover and quickly

overheat. Clearance (A-A) may vary from zero

to

1/16

inch (1.6 mm). Tighten lock screw when adjustment

is correct, being careful not to alter setting.

When the pump is reinstalled on the engine, checkto

see that the pump pulley is aligned with the crank-

shaft pulley and adjust as required.

WATER

PUMP

#131-0152

Water pump #131-0152 is a neoprene impeller type

pump (Figure 21).

Disassembly

1.

2.

3.

4.

5.

6.

7.

Remove the pump end plate screws, end plate,

and gasket as shown in Figure

21,

step a.

Pull out neoprene impeller with a pair of pliers

(Step b).

If further disassembly is required, disconnect the

hoses and remove the two cap screws holding the

pump to the engine (Step c). Lift pump from

engine.

Loosen the set screw on the side of

the

pump and

tap

it

lightly to free the cam from the pump body.

Lift out cam and wear plate (Step d).

Remove the retaining ring (using a screwdriver)

as shown in Step e, and slide the seat assembly

(O-ring and ceramic seal)

off

the pump shaft.

Pry the bellows assembly out of the pump body

by inserting ascrewdriver through the drain slots

(Step f).

Drive the shaft and bearing assembly out of the

pump body using a bearing driver or press. The

bearing is press fit on the shaft and comes

off

in

one integral part.

Assembly

Inspect the pump housing for wear, rough surfaces,

or pitting, and replace if any of theseconditionsexist.

Replace any other worn components such as bear-

ings, seals, or impeller and use a new end plate

gasket.

1.

Apply sealing compound to the sealing lip around

the edge of the bellows seal. Place the bellows

seal in the pump body and drive

it

into place

2. Apply a small amount of Loctite or equivalent on

the outside surface

of

the bearing (Step h).

3. Place the bearing and shaft assembly in the pump

bore and drive into place (Step i). Strike outer

race only to avoid damage to pump shaft and

bearing.

4. Lubricate both sides of the seat assembly (ce-

ramic seal and O-ring) with lubricating oil and

slide assembly over pump shaft. ,The ceramic

portion of the seat assembly should contact the

bellows. Compress the seat assembly against the

bellows, and at the same time push the retaining

ring into its groove on the pump shaft.

5.

Place wear plate and cam

so

notch

in

wear plate

lines up with tang on cam (Step j). Fasten cam to

housing with screw.

6. Align

the

flat spot in the center of the impeller

with the flat spot on the pump shaft. Bend back

the impeller blades nearest the cam and push the

impeller onto the shaft.

Do

not remove the factory

coating of oil from the new impeller before

installing.

(Step 9)-

26

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by any means, is strictly prohibited.

BEARING AND GASKET

SHAFT

ASSEMBLY BELLOWS SEAT

PUMP

/-

BODY

SCREW

d.

RETAINING

RING

WEAR CAM

PLATE

e.

6260.10

8260-8

IMPELLER

f.

--\

8260-6

I/

FIGURE

21.

PUMP

M31-0152

27

Redistribution or publication of this document, 

by any means, is strictly prohibited.

WEAR PLATE

PUMP HOUSING

I

BEARINGS AND SHAFT

IMPELLER IMPELLER

HOUSING GASKET SEAL ASSEMBLY

INTERNAL RETAINING

RING

EXTERNAL RETAINING

RING

7.

8.

FlGURE

22.

PUMPWE319257

Install the pump end plate using a new gasket and

tighten end plate screws to

15-17

inch pounds

(1

-7-1.9 Nm).

Install pump on engine (Step k) and attach hoses.

Assembly

Inspect the impeller housing for wear, rough sur-

faces, or pitting, and replace if any of these conditions

exist. Replace any other worn components, such as

bearings; seals, dr impeller and use a new impeller

housing gasket.

1.

Install the new slinaer on

the

water Dump shaft.

WATER

PUMP

#131-0257

Water pump

#131-0257

is a neoprene impeller type

pump (see Figure

22).

Disassembly

1. Disconnect all hoses and remove the pump from

the engine.

2.

Loosen the pulley set screw and remove the pul-

ley

from the pump shaft.

3.

Remove the impeller housing screws, impeller

housing, and gasket.

4.

Pull

the impeller out of the impeller housing.

5.

Remove the wear plate from the pump housing,

using a screwdriver

to

pry the plate loose if

necessary.

6.

Remove the external retaining ring from the

impeller end

of

the water pump shaft.

7.

Remove the

two

piece seal assembly. The spring

portion of the seal is removed first. The second

portion

of

theseal can be loosened and removed

with a screwdriver or needle-nose pliers.

8. Remove the internal retaining ring from the drive

pulley end of the pump housing.

9.

Carefully drive out the shaft and bearing assem-

bly from the impeller end

of

the housing.

10.

Remove the slinger from the water pump shaft.

1

..

2.

Install the ceramic part of the two piece seal

assembly

in

the

pump housing. The rubber side

of the seal should be toward the bearings.

3.

Coat the inside of the water pump housing and

the outside

of

the ball bearing races with grease.

4.

Insert the water pump shaft into the pump hous-

ing and install the internal retaining ring in the

drive pulley end of the housing.

5. Install the spring portion of

the

two

piece seal on

the pump shaft and secure in place with the

external retaining ring.

6.

Install the wear plate

so

that the notch in the plate

fits into the machining in the pump housing.

7.

Coat the inside of the impeller housing with

grease.

8.

Install the impeller

in

the impeller housing by

twisting it clockwise while pushing

it

into place.

9.

While holding the gasket in place against the

pump housing, install the impeller housing secur-

ing it with four screws removed during disas-

sembly.

10.

Mount the pump on the engine and attach the

hoses.

11.

Align the pump drive pulley with the crankshaft

drive pulley and tighten the set screw.

28

Redistribution or publication of this document, 

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SEAL

SEAT

FIGURE

23.

PUMP

M32-0115

WATER

PUMP

#132-0115

Water pump #132-0115 is a neoprene impeller type

pump (see Figure 23). An alternate pump was occa-

sionally used for part number 132-0115. Refer to the

rebuild procedures for pump #132-0146 if the pump

being serviced does not match the pump shown

in

Figure 23.

Disassembly

1.

2.

3.

4.

5.

6.

Remove the pump end plate screws and lock

washers, end plate, and gasket.

Pull out neoprene impeller with a pair of pliers,

being careful not to damage the pump body.

If further disassembly is necessary, disconnect

the hoses and remove

the

two capscrews holding

the pump to the engine. Lift pump from engine.

Remove the snap ring from

the

drive end of the

pump shaft.

Remove the shaft assembly by tapping lightly on

the

drive end of the shaft. Use a brass or wood

dowel to avoid damaging the shaft.

Slide the seal and spring assembly off the drive

end

of

the shaft.

7. Insert the drive end of the shaft into

the

impeller

end

ofthepump.Guidetheshaftthroughthesea1

until the shaft shoulders against the bearing. Tap

lightly

on

the shaft with

a

brass

or

wood dowel

until the bearing isout.

Also

remove theoil slinger

or O-ring.

8.

Insert the impeller end of theshaft into the engine

end of the pump and guide

it

through until the

snap ring shoulders against the seal seat. Tap

lightly on the shaft until

the

seal seat is out.

9.

The graphite bushing in

the

end plate may be

removed by drilling.

Do

not drill through the end

of the cover plate.

Assembly

Inspect the pump housing for wear, rough surfaces,

or pitting and replace if any of these condition sexist.

Replace any other worn components such as bear-

ings, bushings, seal, seal seat, and impeller. Use a

new end plate gasket when reassembling.

A

new

bushing may be pressed into the end plate after

cleaning. Pump assembly is the reverse of disas-

sembly.

29

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ADAPTER

RING

/

/

SHAFT

/

1

I

SNAP

RING

I

/

/

1

SPLINE

/

BEARING

SPACER

SEAL

b

IMPELLER

WEAR PLATE

FIGURE

24.

PUMPS

#132-0146

AND

M32-0147

WATER

PUMPS

#132-0146

and

#132-0147

Replace any other worn components such as bear-

ings, seal, seal seat, and impeller. Use a new end plate

gasket when reassembling.

Water pumps

#132-0146

and

#132-0147

are neoprene

impeller type

pumps

(see Figure

24).

Disassembly

1.

Remove the pump end plate screws,

end

plate,

and gasket.

2.

Pull

out the neoprene impeller

with

a pair of

pli-

ers, being careful not to damage the

pump

body.

3.

If

further disassembly

is

necessary, disconnect

the hoses and remove the cap screws holding the

pump

to the engine.

Lift

pump

from engine.

4.

Force out

the

shaft assembly and adapter ring

from the

pump

body

by

pressing on the impeller

end of the shaft.

5.

Remove the

set

screw from the side of the

pump

and

lift

out

the

cam and wear plate.

6. Carefully

pry

the bearing seal out of the bearing

bore

using

a screwdriver.

1.

Press the bearing seal into the bearing bore

with

the

lip

towards the bearing side.

2.

Insert the impeller end of the shaft into the drive

end of the

pump

housing and

press

the shaft and

bearing assembly into the bearing bore.

3.

Press the adapter

ring

into the drive end of the

pump

body.

4.

Install the slinger on the shaft and place the seal

spacer

in

the seal cavity.

5.

Install the O-ring

in

the seal bore and press the

seal into the seal bore

with

the

lip

toward the

impeller side.

6.

Coat the top of the cam and the cam set screw

threads with sealer and install the wear plate and

cam assembly. Be

sure

that the cam

is

flush

with

the end cover before tightening the set screw.

7.

Press out the shaft seal from the

pump

body

by

8.

Remove the O-ring, seal spacer, and slinger from

Assembly

screws.

Inspect the

pump

housing for wear, rough surfaces,

or

pitting

and replace

if

any of these conditions exist.

7.

Lubricate the impeller bore with grease and

install the impeller and spline seal.

8.

Lubricate the impeller face with grease. Hold the

new

end

cover gasket against the

pump

housing

and install the end cover, securing

it

with

six

9.

Mount the assembled

pump

on

the

engine and

forcing it toward the impeller bore.

the

impeller bore.

attach the hoses.

30

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FLANGE

PUMP!oDY

SIDESEAL

SHAFT

IMPELLER

PIN

FIGURE

25.

PUMP

M32-0059

WATER

PUMP

#132-0059

Water pump #132-0059

is

a

neoprene impeller type

pump (Figure

25).

Disassembly

1.

Disconnect the

hoses

and remove the cap screws

holding the pump

to

the engine.

Lift

pump from

engine.

2.

Remove

the

end cover screws, end cover and

gasket.

3.

Pull the impeller and shaft assembly from

the

pump body.

4.

Remove

the

impeller pin and

slide

the impeller

off

the

shaft.

5.

Loosen

the

cam

set

screw on theside

of

the pump

and tap

it

lightly

to

free the cam from the pump

body. Lift out cam and wear plate.

6.

Working from the mounting flange

end,

use

a

small drift punch

to

drive the

seals

out toward the

impeller. Remove

the

seal

next

to

the

impeller

bore

first.

Be

careful

not

to

damage the bore

area

around the seal.

Assembly

Inspect the pump housing for wear, rough

surfaces,

or pitting and replace

if

any

of

these conditions

exist.

Replaceany otherworn components such

asseals

or

impeller.

Use

a

new end cover gasket when reas-

sem bling.

1.

Install the impeller

side

seal

with theseal lip

fac-

ing away from the impeller bore. Lubricate the

seal

lip with grease.

2.

Install

the

flange

side

seal

with

the

seal

lip facing

away from the mounting flange. Lubricate the

seal

lip with grease.

3.

Place

the

wear plate in the bottom

of

the

impeller

bore with

the

raised portion

of

the dimple facing

UP.

4.

Coat

the top

of

the cam and cam

set

screw

threads with sealer. Line up

the

dimple in

the

wear

plate with

the

hole in the cam and then tighten

the

set screw.

5.

Slide

the impeller over the shaft and secure with

the impeller pin. Lubricate the shaft with grease.

Check shaft

to

make sure

it

is

free

of

burrs.

6.

Lubricate the impeller bore with grease and then

install

the

shaft and impeller assembly.

Use

a

twisting motion when fitting the impeller into the

impel

ier

bore.

7.

Hold the new end cover gasket against the pump

housing and install theend cover, securing

it

with

three screws.

8.

Mount the assembled pump on the engine and

attach the hoses.

31

Redistribution or publication of this document, 

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COOLING

SYSTEM HOSES

Leakage is the most common cooling system trouble.

Besides losing coolant, leaks may also admit air. This

can result in premature failure of the water pump

impeller.

Test all hoses by squeezing and replace any that have

become cracked and brittle or overly

soft.

Verify that

all clamps and connections are tight and check for

leakage. White, rusty, or colored stains indicate

points of previous leakage.

With the generator set running, observe the water

that is discharged from

the

exhaust outlet.* The

presence of air bubbles indicates that air is being

admitted into the sea water system. Tighten all hose

connections as required.

'Cannot

be

observed

if

Aqualifl

muffler

is

used.

EXHAUST

SYSTEM HOSES

Inspect all exhaust system hoses for leaks and

replace any hoses that are cracked and brittle or

overly soft. Rubber hose should be used only in the

water cooled sections of theexhaust. When replacing,

use only rubber hose designed and approved for

marine exhaust use. Provide adequate support for

rubber hose to prevent sagging, bending, and form-

ation of water pockets. Automotive type tail pipe

hangers should be used to prevent vibration from

being transmitted to the hull. Use two hose clamps,

having a minimum width of 1/2 inch (12.7 mm), at

each end of the hose.

inhalation

of

exhaust gases might

result in serious personal

injury

or

death.

Do

not make any sharp bends

in

rubber

exhaust hose when instaiiing as It might cause hose

failure and gas leakage.

The exhaust line should be at least as large as the

engine exhaust outlet and increased one pipe size for

each ten feet of length.

Inhalation

of

exhaust gases might

result in serious personal injury or

death. Pipe exhaust oufside the hull and do

NOT

terminate exhaust pipe nearany window

or

bulkhead

door openings.

ENGINE WATER

JACKET

AND

CYLINDER

HEAD

External coolant leakage may occur at any of the

joints in the engine water jacket such as the drain

plugs, core hole plugs, or cylinder head joints. Since

expansion or contraction can aggravate leakage, the

block should be inspected both hot and cold while

the engine is running.

Internal leakage occurs when coolant passes into the

engin'e oil through a loose cylinder head joint, worn

water pump shaft seal, or a cracked or porous cast-

ing. The leakage is not visible but can causeextensive

damage to the engine. The coolant mixes with the oil

to form sludge which causes lubrication failure.

Heavy sludge accumulations followed by sticking

piston rings, valves, and valve lifters are symptomsof

internal leakage.

Sometimes internal leaks aretight enough to prevent

coolant leakage but permit exhaust gases to enter the

cooling system. The exhaust gases dissolve in the

coolant, depleting the rust inhibitors and forming

acid which causes corrosion.

A

leaking water pump shaft seal can allow water to

enter

the

crankcase on J-series engines with water

pump #132-0147. Refer to

WATER

PUMP

REPAIR

section for pump repair procedure.

DRIVE BELTS

A V-belt

is

used to drive all captive water system

pumps. Belt tension is adjusted by changing the posi-

tion

of

the pump.

inspect the belt periodically and replace if worn or

glazed. Also check to see if the pulleys are properly

aligned and if the belt tension is sufficient.

To adjust the belt, remove the belt guard and loosen

the water pump mounting bolts.Slide the pump back

and forth in the mounting base slots until the correct

belt tension is obtained. There should be a 1/2 inch

(12.7 mm) deflection when a

15

Ib

(67

N)

force

is

applied at the midpoint of the belt. Tighten the mount-

ing bolts when the correct tension is reached and

reinstall the belt guard.

EXPANSION TANK

An expansion tank

is

required with heat exchanger

and keel cooler cooling to allow for coolant expan-

sion and to provide for separation of air from the

coolant. With front-mount heat exchangers and keel

coolers a separate expansion tank is required. With

side mount heat exchangers the expansion tank is an

integral part of

the

heat exchanger. A pressure cap is

fitted to the top of the tank to maintain system

pressure.

32

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by any means, is strictly prohibited.

PRESSURECAP

The

pressure

cap

increases

the boiling point

of

the

coolant

by

allowing

pressure

to

build

up in

the

cool-

ing system. The increase in boiling point reduces the

chances for coolant loss due to boil over.

A

15

psi

(103.5

kPa) pressurecap

will

raisethe boiling pointof

water to

250°F

(122OC) and the boiling point of a

50/50

mixture

of

water and antifreeze to 265°F

(132OC).

Inspect the pressure cap periodically for freedom of

operation and verify that the spring applies a fairly

stiff tension and is not easily compressed. Peel the

pressure cap gasket back and check for wear and

cracking. Excessive dripping from the overflow tube

may indicate a faulty cap. Replace the cap if

it

mal-

functions or is worn.

PART RATED

NUMBER PRESSURE PSI

130-0589 14

130-0661

7

130-0824

15

130-0553 4

(97 kPa)

(48 kPa)

1

(98 kPa)

(28 kPa)

JSERlES

WITH

SEA

WATER

COOLING

OR

KEEL

COOLER

ACCEPTABLE

LIMITS

PSI

(83-98 kPa)

1

2-1

5

-

-

-

-

3.5-4.5

(24-31 kPa)

Contact with hot coolant might

result in serious

bums.

Do

not bleed

hot, pressurized coolant from a closed cooling

system.

PART

NUMBER

309-0259

309-0179

309-0178

309-0002

309-0151

309-0156

309-0192

309-0252

Pressure caps should be inspected regularly for

gasketwear and spring action.

A

pressure tester may

be used if available to verify that the cap can hold its

rated pressure value. The pressure ratings for

the

various caps are shown in Table

4.

Refer to the appropriate Parts Catalog for the pres-

sure cap part number.

TEMPERATURE

OF

OPEN

CLOSE

230'

f7"

(110°C) 190' f9' (88°C)

190' (88OC) 215"

f5"

(102OC)

180" (83°C) 205"

25"

(97°C)

160"

f5"

(71'C) 200" -1-7' (93°C)

200'

25'

(93°C) 160" 57' (71°C)

250'

f5'

(121°C) 230' -1-7" (110°C)

290" 18" (143°C)

250"

f12" (121°C)

200'

f5"

(93'C)

160"

f7' (71°C)

HIGH

TEMPERATURE CUT-OUT

SWITCH

A

high temperature cut-off switch shuts down the

engine if the coolant in the water jacket reachesa

dangerously high temperature. This normally closed

switch is

a

safety device designed

to

protect the

engine from damage caused

by

overheating (see

Figure

26).

UT-OFF

SWITCH

THERMOSTAT

HOUSING

FIGURE

26.

HWTKO

SWITCH

When

engine

temperature rises beyond a specific

point the switch opens breaking

B+,

allowing fuel

solenoid to close on diesel engines. When coolant

temperature lowers to a safe operating range the

switch closes, permitting engine restarting.

A

second high temperature cut-off switch is some-

times used with generator sets that have a water

injected exhaust system. The second switch

is

mounted on the exhaust elbow (see Figure

13).

If the

exhaust system overheats, theswitch shutsdown the

generator set before the exhaust system components

are damaged. The two switches are wired together in

series

so

that opening either switch will shut down

the engine.

Stopping of the engine due to action of the high

temperature cut-off switch is not

a

normal condition.

Examine the cooling system to determine the cause

of the overheating and repair as required. The open-

ing and closing temperatures for each switch are

shown in Table

5.

Refer to the appropriate

Parts

Catalog for the part number

of

the high temperature

cut-out switch used

in

the engine being serviced.

TABLE

5

HIGH

TEMP

CUT-OUT SWITCH

33

Redistribution or publication of this document, 

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THERMOSTAT

The thermostat is a heat operated valve that controls

engine temperature by regulating the amount of

heated coolant that is discharged (direct flow) or

recirculated (heat exchanger and keel cooler).

As

the

engine temperature increases, the thermostat opens

and allows coolant to circulate. Prior to

the

thermo-

stat opening, a small amount of coolant circulates

through an internal by-pass. The continuous circu-

lation of the coolant through the by-pass allows the

various parts of the engine to warm up at a uniform

rate and avoids localized hot spots.

When the thermostat is not operating properly, the

engine may run too hot or too cold. Overheating may

damage the thermostat

so

that

the

valvewill not func-

tion properly.

Also,

rust or corrosion may interfere

with its operation.

Two

thermostats are used

on

the

4

cylinder J-series

generator sets with front mount heat exchangers.

One thermostat is used on the

1

and

2

cylinder

J-series (all), and on

4

cylinder J-series generator

sets with side mounted heat exchangers. Figure

27

shows the thermostat locations.

If a faulty thermostat is suspected, remove

it

and test

it

for proper opening and closing.

PART

OPENING

NUMBER TEMP.

OF

309-0054 147'

to

154'

164'

to

68OCI

Testing

A

defective thermostat may cause the engine to run

too hot or too cold and must be replaced if faulty.

Thermostats should be tested for proper opening and

closing. If a sticking or faulty thermostat is sus-

pected, test as follows:

WIDE

OPEN TEMP.

'F/MIN.

STROKE

150'/.360

in.

(66OC19.14

mml

1.

2.

3.

4.

5.

6.

7.

309-0130

I

140'

to

145'

Remove thermostat from the cylinder head.

Heat a pan of water

to

the opening temperature

specified in Table

6.

Check temperature using a

thermometer immersed in water.

165'/.130

in.

With the thermostat suspended

in

water at the

specified opening temperature, check to see that

the thermostat begins to open.

It

should be

possible to slip a 0.003 inch

(0.08

mm) feeler

gauge between the valve and thermostat body.

Continue heating the water until the temperature

specified for full opening is reached. Check to see

that the thermostat is open by the amount speci-

fied in Table

6.

Remove

the

thermostat from the hot water and

allow it to cool

in

the surrounding air. The ther-

mostat should close within a

short

time.

If the thermostat sticks

or

does not operate prop-

erly, replace

i€

with

a

new one.

Always

install a new gasket when replacing the

thermostat.

309-0289

Refer to the appropriate parts catalog for the ther-

mostat part number.

(60'

to

63'C) (74OC13.30

mm)

175"

to

182'

(80'

to

84'C) (95OC12.44

mm)

202'/.096

in.

EXPANSION MDJA

MDJB

MDJE

(FRONT MOUNT

HEAT EXCHANGER)

%,THERMOSTAT

EXPANSION MDJA

MDJB

MDJE

(FRONT MOUNT

HEAT EXCHANGER)

MDJA, MDJE.

MDJC, MDJE,

MDJF

(SEA WATER COOLING

AND KEEL' COOLER)

MDJC, MDJF

(SIDE MOUNT

HEAT EXCHANGER)

"'

&

COVER

.

,

R

GAS

MDJC

MDJF

(SIDE MOUNT

HEAT EXCHANGER)

%,THERMOSTAT

WATER

v

FIGURE

27.

THERMOSTAT LO$ATIONS

TABLE

6

THERMOSTAT TEST

I

309-0298

I

157°t01640

I

184'1.360in.

I

34

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by any means, is strictly prohibited.

MARINE

MUFFLERS

A

marine muffler

is

used to silence the generator set.

Some mufflers have an integral water injection inlet,

while others arecooled

by

waterthrough theexhaust

line.

Placement of the muffler in the exhaust line depends

on

the type

of

muffler used. Usually some tailpipe

is

left

to

improve silencing. Refer to the manufacturer’s

installation instructions if the muffler does not func-

tion properly.

All

mufflers must be well supported, and

in

the case of

a

neoprene muffler, completely separated from the

hull

of

the boat. If a neoprene muffler touches the

vessel.

it

increases exhaust noise.

Donotuse themanifoldas a muffler

support because it puts excessive

strain on the connecting exhaust line and can cause it

to break

or

leak, resulting in the escape of deadly

exhaust gases.

35

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by any means, is strictly prohibited.

Fuel

System

FUEL

RECOMMENDATIONS

Fill the fuel tank with a good quality fuel obtained

from a reputable supplier. The quality of fuel used is

important in obtaining dependable performance and

satisfactory engine life. Fuels must be clean, com-

pletely distilled, well refined, and non-corrosive to

fuel system parts.

wARNING

Fuel vapors create fire and explo-

i

sion hazards which might result in

severe personal injury

or

death.

Do

not add gasoline,

gasohol,

or

alcohol to diesel fuel.

Do

not permit any

flame, cigarette,

or

other igniter near the fuel system.

Due

fo

theprecise tolerances of die-

sel injection systems, it

is

extremely

important the fuel be kept clean and free of water. Dirt

or water in the system can cause severe damage to

both the injection pump and the injection nozzles.

Use ASTM2-D

(No.

2

Diesel)

or

ASTMl-D

(No.

1

Diesel) fuel with a minimum Cetane number

of

45*.

Number 2 diesel fuel gives the best economy and

performance under most operating conditions. At

temperatures below 32°F

(OOC),

Number

2-D

fuel

may pose operating problems. At colder tempera-

tures, use Number l-D fuel (if available)

or

use a

“winterized”Number2-D (a blend of Numberl-D and

Number 2-D). The blended fuel is normally called

Number 2-D also, but can be used

in

colder tempera-

tures than non “winterized” Number 2-D fuel.

Do

not add gasoline, gasohol,

or

alcohol

to

diesel fuel. Damage to

fuel injection sysfem

or

engine may result.

‘NOTE

Fuels with Cetane numbers higherthane, may beneeded

in higher altitudes or when extremely

low

ambient temperatures

are encountered

to

prevent

misfires

and resultant excessive

smoke.

-

Use

low

sulfur content fuel having a cloud point of at

least 10 degrees below the lowest expected fuel

temperature. Cloud point

is

the temperature at which

wax crystals begin to form in diesel fuel.

WARNING

Spilled fuel might ignite .and cause

I

serious personal injury

or

death.

Never fill fhe fuel tank when the engine

is

running.

Fuel leaks create fire and explosion

hazards which might result in severe

personal injury

or

death. Always use a length of flexi-

ble tubing between engine and the fuelsupply line

io

avoid line failure and leaks due to vibration. The fuel

system must meet applicable codes.

FUEL

SYSTEM

The fuel system consists of a sediment bowl, fuel

transfer pump, primary filter, secondary filter, injec-

tion pump, injectors, and the connecting fuel lines.

The fuel system, located on the service side

of

the

engine, uses a transfer pump to deliver fuel from the

tank to a high pressure injection pump at about 12 to

14

psi (83-97 kPa);

5-6

psi on MDJA (35-41 kPa). The

injection lines deliver fuel to the injectors at high

pressure and act as fuel distributors to the injectors.

The time interval between injection of individual

injectors is varied in the pump by enginespeed. From

the injection pump, metered fuel is forced through a

delivery valve to the injector lines at about 1900 psi

(13,110 kPa).

As

the cylinder air reaches about

1000°F

(538OC)

on the compression stroke, the injec-

tor sprays fuel into the hot compressed air where it

ignites. The delivery valve

in

the injection pump and a

pintle valve in the injector assist the precision timed

injection

of

fuel into the cylinder.

FILTER SYSTEM

The sediment bowl has a fine mesh screen which

blocks dirt and water entry into the transfer pump,

Figure

28,29.

The dirt and water remain in the sedi-

ment bowl which should be removed for cleaning as

required. The spin-on primary and secondary fuel

filters are replaceable units, that clean the fuel of

extrerney fine

particles

before

it

goes

to

the injection

Pump.

These filters are mounted on a common casting

which bolts to the

oil

fill tube. Positive filtration is

assured because theengine

will

not run if either filter

is loose or missing.

Average pore size

of

the second filter

is

0.0005

inch

(0.0127 mm) smaller than

the

first filter. This means

most particles escaping the first filter are trapped

in

the second filter.

36

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COVER

ROCKERARM

SPRING

SEDIMENT

BOWL

FIGURE

28.

FUEL SYSTEM-LATEST MODELS

AIR

FUEL

TRANSFE

f

SECONDARY

TANK

-

FUEL

FILTER

FIGURE

29.

FUEL SYSTEM-OLDER MODELS

m

FUEL TRANSFER

PUMP

The fuel transfer pump (Figure

30)

is a diaphragm

and check valve type pump operated by a cam lobe

on the engine camshaft. The pump cam follower has

a

wide surface to prevent wear as

it

rides on the

camshaft lobe. The priming lever is manually oper-

ated to prime and bleed

the

system.

The diaphragm spring maintains required fuel pres-

sure to the injection pump. Fuel pressure should be

as follows when operating at 1800 rpm:

MDJA

.............................

.5

to

6

psi

(34.5

to 41.4 kPa)

(83

to

97

kPa)

MDJC, MDJF

....................

.12 to 14 psi

(83

to

97

kPa)

.

MDJB, MDJE

....................

.12 to

14

psi

**

*

**

Prior to 1962

and

October through

December

1964

-

2

to3

psi

(14

to

21

kPa).

Prior

to

1962

-

2 to

3

psi

(14

to

21

kPa).

ROCKER

ARM

ROCKER

ARM

PRIMING^

LINK

A687

FIGURE

30.

FUEL

TRANSFER

PUMP

Fuel pump pressure may bechecked by connecting a

pressure gauge and tee at the fuel outlet.

A

vacuum

gauge connected at the fuel inlet will show whether

the pump has enough capacity to

lift

fuel about6feet

(1.86 m). The fuel pump should produce

15

to 18

inches (381 to 457 mm) of vacuum at sea level.

Fuel Pump Removal Disassembly

1.

Remove pump inlet and outlet lines. Remove

two

capscrews holding pump to engine and

lift

it

off.

2.

Notch the pump cover and body with afileso they

can be reassembled

in

same relative positions,

and remove six screws holding them together.

3.

Tap body with a screwdriver to separate

two

parts. Do not pry them apart; this would damage

diaphragm.

4.

Drive out rocker arm hinge pin.

5.

Remove rocker arm, spring, and link.

6.

Lift

out diaphragm assembly and diaphragm

Repair

A

kit is available for replacement

of

the diaphragm

and spring. If the diaphragm is leaking or broken,

check for diluted crankcase

oil.

If necessary, replace

diaphragm. Occasionally, a worn rocker arm pin will

cause crankcase oil leakage. If this is the case, the

pump should be replaced.

spring.

37

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Assembly

1.

2.

3.

4.

5.

6.

7.

When installing a new diaphragm, soak it in fuel

before assembling. Insert diaphragm spring and

soaked diaphragm into pump body.

Insert link and rocker arm into body and hook it

over diaphragm pull rod. Align rocker arm with

rocker arm pin hole and drive in pin. The priming

lever must be in position shown in Figure30 when

installing rocker arm.

Compress rocker spring and install between the

body and rocker arm.

Assemble cover to body, with notch marks lined

up. Install screws but do not tighten.

Fuelleakageis a fireand expio-

n

sion hazard fhaf might cause

severe personal injury or death. Use care when

reassembling fuel pump. All parts must align per-

fecfly or pump will leak fuel.

Push rockerarm in onefull strokeand hold

in

this

position to flex diaphragm.

Tighten cover screws alternately and securely,

then release rocker arm.

Install pump on the engine and repeat pressure

test.

INJECTION NOZZLES

Onan diesel engines use hydraulically operated,

pintle-type injection nozzles, Figure 31. They are fac-

tory adjusted to open at 1900 to

1950

psi

(13,110

to

13,455

kPa). However, after several hundred hours of

operation the nozzle pressure will decrease to about

1750

psi

(1

2,075 kPa).

Refer to the throttling pintle type nozzle information at the end of

thissection for information regarding MDJEenginesusing Bryce/-

Kiki fuel systems.

COVER

PRESSURE

A&

GASKET

:

SPINDLE

ASSEMBLY

NOZZLE

CAP

NUT-(

7

SHIELD GASKET

f-

F

FUEL

CUP

GASKET

CYLINDER

HEAD

A,

7

\

Ul

A0aQ-j

FIGURE

31.

INJECTOR NOZZLE ASSEMBLY INSTALLATION

Operating Principle

Nozzle operation

is

as follows:

1.

2.

3.

High pressure fuel from the injection pump enters

the fuel inlet stud and flows down drilled pas-

sages in the body of nozzle holder, Figure 32.

Fuel enters fuel duct and pressure chamber of

nozzle assembly. When fuel pressure overcomes

preset pressure of the adjusting spring, the pintle

is forced upward off its seat and a fine mist of fuel

is injected into the pre-combustion chamber,

where

the

vaporized fuel mixes with the hot com-

pressed air.

If compression temperatures are high enough,

the fuel-air mixture ignites. Injection continues

until the spill port clears the top of the metering

sleeve in the injection pump and dumps the high

pressure fuel into

the

sump, allowing the pres-

sure spring to close the injector and cut off fuel

injection to the cylinder.

Do

not disfurb fhe injector pressure

adjusfing screw;

it

cannof be reset

without proper equipment.

Bypass fuel is returned to the tank after each injection

cycle by a return line from the nozzle. A fuel return

fitting combines the return fuel from the injectors

with the flow-through fuel from the injection pump

bleed valve. A return line connected at this point

returns the combined fuel to the fuel supply tank.

.

FIGURE

32.

INJECTOR NOZZLE AND HOLDER ASSEMBLY

38

Redistribution or publication of this document, 

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Nozzle

Spray

Pattern

A

nozzlesuspected of misfiring can bechecked in the

field by removing it

from

theengineand reconnecting

it to the high pressure line. Thespray pattern (Figure

33)

can be observed as the engine

is

cranked.

Fuel penetration

of

the skin might

-1

causesevere pe~onalinju~.

Do

not

let the nozzle high-pressure fuel spray against

skin

surfaces.

2

-.#

..a*.

\-

FIGURE

33.

NOZZLE SPRAY PATTERN

If streamers are visible, the pattern is badly distorted;

or if the nozzle drips before it reaches opening pres-

sure,

it

is defective and must be cleaned or replaced.

Cleaning

is

the most important part

of

nozzle maintenance. Make

sure the work area and equipment

are

exceptionally clean.

A

second method for identifying a misfiring nozzle is

to remove the exhaust manifold, run the engine, and

observe the exhaust ports for the following con-

ditions:

Heavy Load

-

Black smokey exhaust from any one

cylinder could indicate poor nozzle condition.

Light or No Load

-

Blue/white smoke from any one

cylinder could indicate poor nozzle condition.

Adjustment:

To adjust the opening pressure, remove

each nozzle from the engine. Remove the plug from

the center of the cap nut, and loosen the cap nut.

Install the nozzle to be tested on astatic-fuel, nozzle

testing fixture (may be purchased from Onan). Fol-

lowing the instructions on the tester, adjust theopen-

ing pressure to

1750

psi (12,075 kPa) by turning the

pressure; counterclockwise decreases

it.

Do

not try

to

adjust

the pressure without a testing fixture.

*

.

adjusting screw. Clockwise adjustment increases the

1.

Remove each nozzle assembly from engine and

remove fuel inlet and return lines.

2.

Clamp

nozzle

holder

body

in

a

vise

and

remove

nozzle cap nut and nozzle.

3.

Install nozzle cap nut loosely to protect lapped

surface

of

the

holder body.

4.

If necessary, to disassemble nozzle further,

reverse pressure adjusting screw and lift out

spring and spindle assembly.

Do

not

attempt

io

disassemble the

nozzles

or

adjust nozzle pressure

without the proper test equipment.

A

nozzle pressure

tester

is

essential to do a satisfactory

job.

The cleaning procedure (Figure

35)

is

extremely important when

disassembling injection equipment Always rinse in clean fuel

before

reassembling.

Injection

Nozzle

Tester

Testing and adjustment can be performed only with a

nozzle tester, Figure

34.

Do

not attempt to disassem-

ble the nozzles or adjust nozzle pressure without the

proper test equipment.

Opening pressure, leakage, and spray pattern can be

checked using the tester.

If

any of the above condi-

tions appear (except opening pressure), inspect the"

nozzle valve and seat with a magnifying glass for

erosion, scoring, etc. If cleaning with solvent does

not correct the condition, a new nozzle tip will be

required. The opening pressure can then be set and

spray pattern checked.

FIGURE

34.

INJECTION NOZZLE TESTER

Disassembly:

When removing and disassembling

nozzles, separate and label all components of each

nozzle. Never interchange components between

nozzles.

Neverusehard orsharp tools, emery

paper, grinding powder,

or

abras-

ives

of

any kind

on

nozzles or they may be damaged.

39

Redistribution or publication of this document, 

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Soak each nozzle

in

fuel to loosen dirt. Then clean

inside with a small strip of wood soaked in oil. Clean

spray hole with a wood splinter. If necessary, clean

the outer surfaces of the nozzle body with a brass

brush but

do

not attempt to scrape carbon from the

nozzle surfaces. This can severely damage the spray

hole. Use a soft oil-soaked rag or mutton tallow and

felt to clean the nozzle valve.

1.

Use a brass type scraper tool to remove hard

carbon depositis from nozzle body valve seat.

2. After scraping thecarbon, polish the valve seat by

using a round pointed stick dipped in tallow.

Pol-

ishing should restore seat to its original finish

unless

it

is scored.

-

3.

Use a special hooked type scraper to clean the

nozzle pressure chamber gallery. The hooked

end of scraper is inserted into the gallery and then

carefully rotated.

4.

5.

Clean nozzle valve and polish with tallow and a

wooden polishing fixture. Take care to remove all

traces of tallow when finished.

6.

Examine nozzlevalveand body with a magnifying

glass. If erosion and scoring conditions are found,

replace the valve and body.

7.

Use a lapping plate and compound for flat lap-

ping of nozzle parts which depend on a lapped

surface for sealing. A figure

“8”

motion is used.

8.

It

is essential that the nozzle body be perfectly

centered in the cap nut when reassembling noz-

zle.

A

centering sleeve,

as

shown,

is

used for this

Small holes in tip of nozzle body can be cleaned

with

afinewireslightlysrnallerthan

thesizeofthe

hole.

purpose.

FIGURE

35.

NOZZLE CLEANING

40

Redistribution or publication of this document, 

by any means, is strictly prohibited.

NOZZLE

REPAIR

If cleaning

will

not eliminate a nozzle defect, replace

the nozzle or take

it

to

an authorized diesel

service

station.

Do

not attempt to replace parts of the nozzle

except for nozzle and pintle assembly.

.

Assembly

Rinse both valve and nozzle thoroughly before

assembly and coat with diesel fuel. The valve must be

free in the nozzle.

Lift

it

about

1/3

out of the body.

It

should slide back to its seat with,out aid when the

assembly is held at a 45-degree angle. If necessary,

work the valve into its body with clean mutton tallow.

SOLENOID

.

WIRE

TO

CONTROL

1.

Clamp nozzle holder body in a vise.

2. Set valve in body and set nozzle over

it.

3.

Install nozzle cap nut loosely.

4. Place centering sleeve over nozzle for initial

tightening. Then remove centering sleeve to pre-

vent

it

from binding between nozzle and cap nut.

5.

Tighten nozzlecap nutto50-55ft.-lb. (68-75Nm).

FIGURE

36.

FUEL SOLENOID

NOZZLE INSTALLATION

Before installing the injection nozzles in the engine,

thoroughly clean each mounting recess.

A dirty mounting surface could permit blow-by, caus-

ing nozzle failure and a resulting power

loss.

1.

Install a new heat shield

to

head gasket in

cylinder head recess.

2. Install heat shield, heat shield gasket, second

heat shield, and nozzle gasket.

3.

Insert nozzle assembly into recess.

Do

not strike

tip against any hard surface.

4.

Install nozzle flange and two capscrews. Tighten

capscrews alternately to avoid cocking nozzle

assembly. Tighten each to 20-21

ftlb.

(27-28 Nm).

FUEL SOLENOID

The fuel shutoff solenoid (Figure

36)

is also referred

to as a governor solenoid, as

it

over-rides the gover-

nor during shutdown. The solenoid is mounted on a

bracket and controls the injection pump operating

lever. When energized, the plunger pulls into the

solenoid body. When de-energized, the solenoid

spring forces the plunger out against the operating

lever to hold

it

in the fuel shutoff position.

The solenoid has two

coils.

Both are energized

for

pulling the plunger up. When the plunger reaches the

top,

it

opens a set

of

contacts, de-energizing the pull-

in coil. The other coil holds the plunger up while the

engine is running and de-energizes when the engine

shuts down.

To

test the solenoid, check plunger operation and

current draw with 12-volt input. Current draw with the

plunger up should be about

1

amp. If

it

is much

greater, the contacts did not open.

The solenoid plunger should be adjusted

so

it

fully

stops injection when in the de-energized position. To

adjust the plunger length, turn thescrew and jam nut

on

the

plunger bottom

in

or out. If the plunger sticks,

remove the solenoid from its mounting plate and

clean the plunger and recess

in

the solenoid.

FUEL INJECTION

PUMPS

Onan

DJ

series diesels are equipped with American

Bosch fuel injection pumps. Single cylinder engines

use the model PLB;

the

four cylinder engines use the

model PSU pump. Until recently, the two cylinder

diesel engines have been using a

PSU

pump. Now,

the

MDJE

engines use either a Bryce or a Kiki fuel

injection pump. For Bryce/Kiki pump information,

turn to the back of this section. The fuel injection

pumps are constant stroke, lapped plunger type and

operated by the engine camshaft. They deliver an

accurately measured quantity of fuel under high

pressure to the injection nozzles.

A

constant bleed-check valve

is

furnished with all PLB and PSU

pumps. The bleed valve automatically bleeds

off

a restricted

amount

of

fuel,

fuel

vapors, and

small

quantifies

of

air

to

prevent air

accumulation

in

the

fuel

sump areaof

thepumps.1hisvalveshould

open at pressures between

0.9

and

3.0

psi

(6.2

and

20.7

kPa).

41

Redistribution or publication of this document, 

by any means, is strictly prohibited.

The port closing (PC) mark

is

not stamped on replacement fly-

wheels.Therefore, the PC markmust beestablished by measuring

the piston drop with the cylinder head removed prior

to

injection

pump timing. Since injection occurs at the port closing position,

the PC mark can be located only by comparing the old flywheel

with the new one, or

by

measuring the piston drop from its top

center position on the compression stroke

of

number one cylinder.

Piston drop data

is

given in Table

7.

PISTON

DROP

Inches

I

mm

TABLE

7.

PISTON

DROP

DATA

.

PORT

BTC

ENGINE CLOSING

0.155

0.102

I

2.59

I

MDJA

I

17degrees

0.128

I

3.25

I

MDJB

&

MDJC

I

19

degrees

-

(Begin Spec

P)

(Prior

to

Soec

P)

3.94

MDJB

&

MDJC

21

degrees

0.128

0.115

0.128

3.25

MDJE Spec A-AA

19

degrees

2.9

MDJE Begin Spec AB

18

degrees

3.25

MDJF

19

dearees

CAUT,ON

Replace any injection pump that

Ez3

troubleshooting procedures prove

to be malfunctioning.

Do

not attempt unauthorized

repair procedures

on

the injection pumps.

Fuel injection pumps must pass stringent quality

inspections, and tests with precise settings and

adjustments, in order to meet Onan’s performance

and reliability requirements. Therefore,

it

must be

clearly understood by the owners and by Onan ser-

vice personnel that tampering or inept repair attempts

can cause irrepairable damage to the pumps that will

not be covered by

the

manufacturers’ warranties or

exchange agreements. Contact an authorized Amer-

ican Bosch Service station or Distributor for expert

repair service on injection pumps.

The Repair service should include cleaning, part

replacement, static pressure tests for internal and

external leaks, internal pump timing, and calibration

and adjustment to the manufacturer’s specifications.

MDJA

INJECTION

PUMP

INJECTION

LINE

CAP

NUT

VALVE

HOLDER

SPRING

BLEED

VALVE

ASSEMBLY

PUMP

HOUSlN

GASKET

GASKET

LOCATING

SCREW

PLUNGER

BARREL

CONTROL SLEEVE

CLOSING PLUG

UPPER

SPRING

SEAT

PLUNGER

SPRING

PLUNGER RETAINING

RING

LOWER

SPRING

SEAT

A

PLB

injection pump (Figure

37)

is used on the

MDJA Series e’ngines. The cross-sectional view

shows the internal parts and the operating lever and

control shaft.

The pump consists of a housing, pump plunger and

barrel, the plunger return spring with its seats, and

the control sleeve and its operting shaft. The housing

contains the fuel sump, delivery valve assembly,

delivery valve holder, and the union nut for connec-

tion

of

the high pressure discharge tubing.

Repair

Most fuel system troubles are not due to a faulty

injection pump.Test the rest of

the

fuel system before

condemning the injection pump.

Onan discourages field repair of the injection pump

because of the exceptionally close tolerances be-

tween parts and the specialized equipment necessary

for repair. The injection pump is an expensive part

of

the unit and even a particle

of

dirt as fine as talcum

powder could score its working surfaces. If the rest of

the fuel system is in working order and fuel delivery is

abnormal, remove the pump for replacement or

repair.

Removal

Remove the pump inlet and outlet lines. Remove the

two capscrews holding the pump to the engine and

lift

it

off. Do not lose the shims. They time the injec-

tion pump to the engine. Cap all openings in the

pump and fuel lines to keep dirt out of the fuel system.

Timing

Timing the pump to the engine determines the port

closing point

(17

degrees BTC)

PC

mark on flywheel.

See Figure

38.

The

helix

position

controls

port

open-

ing and is, in turn, controlled by the throttle setting.

FIGURE

37.

PLB INJECTION PUMP COMPONENTS FIGURE

38.

INJECTION PUMP TIMING

42

Redistribution or publication of this document, 

by any means, is strictly prohibited.

The most accurate method of injection pump timing

is

with

a

depth micrometer

(Method

7).

However, if a

depth micrometer is not available, time

it

by

Flowing

the

Pump

(Method

2).

the exhaust stroke.

Method

2.

Flowing

fhe

Pump:

1.

Install pump with 0.006-inch (0.15 rnm) shims

between pump and pad.

2.

Loosen the delivery valve holder to relieve

pressure on spring. See Figure

40.

3.

Rotate the flywheel

to

about

15

degrees before

the port closing (PC) point. Blow in the pump

inlet

and rotate the flywheel slowly clockwise

until airstopscoming outofthe pumpout1et.Thi.s

is

the

port closing point.

4.

Measure the distance from the point where port

closing occurs to the

PC

mark on the flywheel.

Find the thickness of shims to be added from the

table that follows.

..’”

Injection pump must be timed on the compression stroke, not on

5.

Install the pump.

Method

7.

Depth Micrometer:

1.

Install pump tappet in its recess and position fly-

wheel on the port closing mark (PC) of the com-

pression stroke.

2.

Using a depth micrometer, measure the distance

from the pump mounting pad on the crankcaseto

the tappet center. See Figure

39.

3.

Subtract from the port closing dimension of the

pump 1.670-inch

(42.42

mm) the depth obtained

in

step

2.

The result is the thickness

of

shims

necessary to time the pump correctly.

Thicknessof shims mayvaryfrom0.006 to0.052-inch (0.15 to

1.82mm).If itdoesnotfaliwithin

theselimits,checkcamshatt

and tappet for excess wear or improper assembly.

4.

Select the correct shims for the required thick-

5.

Install the pump.

ness.

FIGURE

39.

DEPTH

MICROMETER

FIGURE

40.

LOOSENING DELIVERY VALVE HOLDER

Installation

Prior to mounting the injection pump to the cylinder

block, follow steps

1

through

3.

1. Slide the shim or shims (using proper thickness

of shims for correct timing) over the pilot until

they are flat

on

the pump flange. See Figure 41.

2.

Dip the seal (O-ring)

in

engine lubricating

oil.

3.

Slide the seal over the pilot until tight against the

shim or shims.

43

Redistribution or publication of this document, 

by any means, is strictly prohibited.

SHIM

SELECTION

USE THIS CHART WITH

METHOD 2.

I

,

DISTANCE ADD

MEASURED THESE

STEP

4

SHIMS

0.1

0.01

0

0.2

0.014

0.3

0.01

8

0.4

0.022

0.5

0.026

0.6

0.030

INJECTION

we in Inches)

DISTANCE

I

ADD

MEA:FtD

I

HHnlIiE

0.038

0.042

1.0

0.046

0.050

FIGURE

41.

SHIMMING THE PILOT

With shims and seal in place insert the pump into

cylinder block mounting pad, and insert mounting

screws. Torque the mounting screws (tighten alter-

nately) to

18-21

ft.-lb.

(24-28

Nrn).

Install the fuel inlet line and governor linkage. Bleed

the pump, and then install the fuel outlet line (see

INSTALLA

TION

section).

PSU

OR

MODEL

50

INJECTION

PUMP

The

PSU

or model 50 injection pump (Figure

42)

is

used on Onan

2-

and 4-cylinder water-cooled diesels.

Pumps that are almost identical, with only two injec-

tor line outlet ports, are used on the

two

cylinder

models.Thefunction of the pump asadistributorand

its location on the service side of the engine are the

same on both

2-

and 4-cylinder engines.

Repair

Internal repairs on the injection pumps require spe-

cial tools and step-by-step procedures for disassem-

bly and reassembly.

Replace wifba newpump anypump

G

that troubleshooting procedures

prove to

be

malfuncffoning.

Do

not attempt unaufho-

rized repair procedures

on

injection

pumps.

FIGURE

42.

INJECTION PUMP

Pump Operation

The pump face gear mates with and is rotated by a

drive gear on the engine camshaft, Figure

43.

The

face gear, pilot ring, and the reciprocating plunger in

the pump are rotated continually to assure positive

fuel distribution.

A

multi-lobed cam on the camshaft

rides on atappet assembly in the pump and drives the

plunger up and down.

OPERATING

LEVER

b

fm

A-

I

ll

T

MULTI-LOBE

CAM

FIGURE

43.

INJECTION PUMP TO CAMSHAFT

RELATIONSHIP

44

Redistribution or publication of this document, 

by any means, is strictly prohibited.

\TIMING

BUnoN

FIGURE

44.

INJECTION PUMP (CUTAWAY

VIEW)

Pump Cutaway View

Thecutawayview in Figure44showsthecontrol unit

operating lever, metering sleeve, delivery valve,

plunger, and drilled passages to the plunger and

injection lines.

A

timing button of very precise thickness transmits

motion from the tappet to the plunger and adjusts

plunger timing for the fuel pumped to each injector

during operation. Plunger reciprocation and rotation

are phased

so

that only one fuel injector is served

during the affective portion of each plunger up

stroke. The high hydraulic pressure developed is

required to open the pressure operated fuel injector

nozzles, which inject the fuel in a fine mist into the

combustion chamber. Fuel delivery control, full load,

and shutoff are regulated by the up-and-down move-

ment of the fuel metering sleeve. The sleeve is con-

trolled by the operating lever on the outside of the

pump. Fuel is injected only during the high velocity

portion of each plunger up stroke.

When the tappet slips

off

each lobe of the camshaft,

the

spring loaded plunger is forced down, opening

the fuel supply port to

the

fuel sump. This allowsfuel

under

low

pressure from the transfer pump and fuel

sump to fill the cavity between the top end of the

plunger and the delivery valve. The plunger is then

ready for the up stroke.

,

SLEEVE

Metering Sleeve Operation

The metering sleeve is positioned by the operating

lever of the governor control unit, Figure 45. An

eccentric pin on the end of

the

control shaft engages

aslot

in

the

metering sleevesothat aslight rotation of

the control shaft causes thesleeve to ride up or down

on the plunger.

As

the

camshaft and face gear rotate,

the drive key and a vertical slot in the face gear trans-

mit rotation to the plunger. Rotating the plunger

aligns outlet groove with the appropriate injection

line outletforthe injectorto fireon each pumpstroke.

OPERATING

LEVER

ECCENTRIC

PIN

,.

q

_1_1

SLEEVE

FIGURE

45.

METERING

CONTROL

45

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Delivery Valve Function

The delivery valve maintains

300

to

600

psi

(2070

to

4140 kPa) line pressure in the injector lines with the

engine running, Figure46. This pressure increases to

about

1900

psi

(13110

kPa) on each stroke of

the

injection pump plunger. The trapped fuel is held in

the lines at all times, even though the pressure bleeds

off during shutdown periods. When the lines are full

of fuel, only a couple turns of the crankshaft are

required to build up enough line pressure for firing

the injectors.

Code

16orS

15orR

14orP

13orN

12orM

SPRING DELIVERY VALVE

/

PartNo.

Size Code

PartNo.

Size Code

PartNo.

Size

Inch

mm

Inch

mm

inch

mm

147-0186 .134 3.404

1

orA

147-0147 .119 3.023 6orF 147-0152 -101 2.565

147-0187 .131 3.357 2orB 147-0148 .116 2.946 7orH 147-0153 .098 2.489

147-0188 .128 3.251 3orC 147-0149 .113 2.870 8orI 147-0154 .095 2.413

147-0189 .125 3.175

4orD

147-0150 .110 2.794 9orK 147-0155 .092 2.337

147-0190 .122 3.099

5orE

147-0151 .lo7 2.718 10orL 147-0156 .089 2.261

11

orStd.

147-0161 .lo4 2.642

I

Preservative oil applied

to

the new

injection pump during assembiy may

cause the pump to stick. Forcing the plunger or gear

will damage the pump. Dissolve preservative by soak-

ing pump in clean filtered diesel fuel for

75

to

30

minutes.

TIMING BUTTON CODE

The timing button has a code number or letter

stamped on

it

that corresponds to its dimension in

thousandthsof an inch. SeeTable

8.

Figure47 shows

the timing button. One button will provide the correct

port closing.

.

SEAT

CODE LETTER

OR

NUMBER

STAMPED

ON

SIDE

LINE PRESSURE

FIGURE

46.

DELIVERY VALVE CLOSED -PLUNGER DOWN

Keeping the fuel system clean

is

extremely important.

A

fine particle

of dirt can ruin fhe injection system in a very short

time.

If

the fuel system is opened for any reason, cap

all openings and place the parts removed In clean

diesel fuel. Before installing new

or

used pads, wash

them in clean fuel and install them wet.

FIGURE

47.

TIMING

BUITON

CODE

TIMING BUTTON THICKNESS

Injection pump kits include a pump and four buttons

which will time most of the engines. The button and

retainer ring are not assembled.

The injection pump on each engine must be timed to

that engine by using a timing button of specific thick-

ness. Each new pump has its port closing dimension

stamped on the pump mountingflange.The portclos-

ing dimension is measured at the factory using a

number

11

or standard button.

Pump timing is critical. use one of the two timing

methods to determine correct new button thickness.

If the correct button

is

not supplied with the replace-

ment pump refer toTable

8

and order the correct one

from your Onan dealer.

TABLE

8.

TIMING

BUTTONS

Redistribution or publication of this document, 

by any means, is strictly prohibited.

TIMING

PSU OR

MODEL

50

INJECTION

PUMPS

One

of

two

methods can be used to determine the

proper timing button to time the fuel injection pump

correctly to the engine.

Method

1-Timing

by

Calculation

This procedure is used, when all dimensions are

available for replacing an old pump, before the pump

is installed. Timing by calculation requires the port

closing dimension and button thickness from the

pump being replaced.

It

also requires the port closing

dimension of the new pump. Put the dimensions in

the PORT CLOSING FORMULA and calculate the

new button thickness. After determining the timing

button thickness find the button code

in

Table

8.

If

injection pump is removed from the engine, make

sure the steel shims between pump and cylinder

block mounting remain the same. These shims main-

tain proper gear backlash.

Do

not change the pump mounting

Ez2

shim’s total thickness or the proper

pump gear to camshaft

gear

mesh will

be

affected.

The shim thickness is establishedat the factory dur-

ing engine assembly and does not change unless a

new cylinder block is installed.

Port

Closing Formula:

The procedure for determin-

ing the proper port closing (PC) timing button for a

new or replacement pump is as follows:

1.

Remove old pump.

2.

Determine port closing dimensions and original

button thickness from old pump.

A.

Write down port closing dimension given on

old

pump flange and port closing dimension

given on new pump flange. See example.

B.

Use a pair of channel lock pliers

or

screw-

driver to remove tappet, retaining ring, and

timing button from old injection pump (Figure

48).

Use nurnberor letter code on timing but-

ton to obtain dimension of old timing button

fromTable8.Thiscodeshould

bethesameas

the code number stamped on injection pump

(Figure

48).

OnallPSUpumpsbesureto

E3

hold the pump drive gear

securely against the pump body when remov-

ing the tappet. If not, the pump will come

apart and be difficult

to

assemble. The meter-

ing sleeve wlll drop off the plunger if the gear

and plunger are removed.

If

fhe plunger port

is

not closed by the sleeve, there wlll be no

fuel delivery and the pump wiil not operate.

3.

Add dimension on

old

pump flange

to

timing but-

ton dimension. See example.

Example:

Inches

(mm)

Port

closing dimension

of

old pump

1.109 (28.169)

Button thickness

of

old pump

+

.107 (2.719)’

Total

1.216 (30.887)

Port

closing dimension

of

new pump

-1.094 (27.788)

Required button thickness

of

new

pump

.122 (3.099)

4.

Subtract port closing dimension given on new

pump flange from total dimension for old pump.

5.

Use dimension calculated to select new timing

button that is nearest the calculated dimension.

Install new timing button

m

pump and install

tappet on pump.

6.

Install injection pump. Referto lNJECT/ON

PUMP

INSTAL LA TI0 N.

MAXIMUM

THROTTLE

STOP

SCREW

D

O-RING

KEEPS TA

IN

DURING

HAND

GROOVE

/

TAPPET

FIGURE

48.

TAPPET

REMOVAL

Method

2-Flow

Timing Injection Pump

This procedure is used when dimensionsfrom the old

pump are lost or when a new cylinder block is

installed. Clean diesel fuel is used, when

flow

timing,

to determine if the proper timing button has been

installed.

If the pump is removed from the engine, be sure the

steel shims between the pump and the cylinder block

mounting are the same. These shims maintain proper

gear backlash. The number stamped on the cylinder

block injection pump mounting pad indicates the

proper shim thickness. This thickness does not

change when anew pump is installed.

It

changes

only

when a new cylinder block is installed.

47

Redistribution or publication of this document, 

by any means, is strictly prohibited.

1.

Install

No.

12 timing button in new injection

pump. Remove delivery valve cap nut and holder,

take out spring and replace valve holder and cap

nut (Figure 49 and

50).

CAP NUT

GASKET

I

CAP NUT

FIGURE

49.

LATE

MODEL DELIVERY VALVE ASSEMBLY

VALVE SPRING

GASKET

CAP SCREW

FIGURE

50.

EARLY MODEL DELIVERY VALVE HOLDER

2.

Install new injection pump. Refer to

lNJECTION

PUMP

INSTALLATION.

3.

Remove

No.

1

injection line. Install

No.

1

injection

line with top end of line

in

pump outlet. Place an

open container under open end

of

No.

1

injection

line (Figure

51).

4.

Disconnect governor linkage at ball joint and

hold control arm up at maximum fuel position.

F

-

----

/3'f

6f''

TEST

POSITION

b

Fl

A642-I

CONNECT

FUEL RETURN

LINE HERE

FLEXIBLE LINE)

-----

PUMP

W

FIGURE

51.

FUEL LINE

TO

INJECTORS

5.

Rotate flywheel clockwise (when facing front of

engine [Figure

521

to point where

PC

mark on

flywheel is about

15

degrees

(1.25

to

1.50

inch

[32-38

mm])

before timing pointer

on

gear cover

(compression stroke of

No.

1

cylinder).

Makesure that both rocker armson

No.

1

cylinder

are free to move indicating the valves are closed.

If

fuel tank is disconnected, use a separate con-

tainer of fuel and connect a short fuel line

between the transfer pump inlet and

the

fuel con-

tainer. The pump has enough suction to pull fuel

out of

the

container.

Ignition of fuel might cause

IWIRNlNC)

serious personal

injury

or death

by fire or exploslon.

Do

not

permit any flame,

cigarette, or other Igniter near the fuel system.

!!

I

P.C. (PORT CLOSING)

,

FIGURE

52.

PORT

CLOSING POSITION

48

Redistribution or publication of this document, 

by any means, is strictly prohibited.

6.

Manually operate fuel transfer pump (Figure

53)

until

fuel, free of

air,

flowsfrom

open

end

of

No.

1

injection

line

into

container

(Figure

51).

WORK TRANSFER

PUMP

PRIMING

LEVER

UNTIL

CONTAINER

quL,

FUEL

FLOWS INTO

11

LOWEST

POSITION

An3n

Rev

FIGURE 53. OPERATING

TRANSFER

PUMP MANUALLY

7.

Continue operating transfer pump while assistant

rotates flywheel slowly in clockwise direction.

Stop flywheel rotation at exact point that fuel

stops flowing from

No.

1

injection line (one drop

in

2

to

5

seconds is allowed). This point is the

injection pump plunger port closing, regardless

of flywheel position.

Timing is correct if port closign occurs when PC

mark on flywheel aligns with timing pointer (Fig-

ure

52).

If the marks do not line up, timing is either

early or late and the timing button must be

changed.

If Step? indicates port closing is incorrect (late or

early) proceed as follows (See Examples):

A. Mark flywheel

in

0.1

inch

(2.54

mm) gradua-

tions (about five marks each direction) from

PC mark for calculating required change

in

button thickness, Figure

54.

.

POINTER

POINTER

EXAMPLE

1

FLYWHEEL

FRONT

SIDE

FIGURE

54.

TIMING

MARKS

8.

Measure distance

in

tenths of an inch (or mm)

from PC mark on flywheel to point of actual

port closing found

in

Step

7.

C.

Multiply distance measured times

.003

inch

(0.76

mm) to determine the difference

in

thickness required for new button.

One

degree

of

crankshaft rotation

equals

the 0.1-inch

graduation

or

.OO3-inch button thickness

for

timing.

Example

1.

The port closing time is

late

by 0.3-inch

(7.6

mm)

measurement

(3

x

-003"

=

.009"

[3

x

.076

=

.229

mm]).

Since

0.1

inch

(2.54

mm)

equals

.003

inch

(.076

mm)

in

button thickness, the installed button is too thin by

.009

inch

(0.229

mm).

This means a button

.009

inch

(0.229

mm) thickerthan theoneinstalled is required to time port

closing

so

that PC mark on flywheel aligns at the timing

pointer when fuel flow stops.

Example

2.

If

PC timing

is

too

early

by 0.4-inch

(10.2

mm), multiply4

x

.003

=

.O

12

inch

(4

x

.076

mm

=

0.305

mm). In this case,

a

button

.012

inch

(0.305

mm) thinner

than the one installed

is

required.

D.

After determining which timing button is

required, remove injection pump and install

the correct button.

8.

Install new injection pump with

No.

1

injection

line

connected to injection nozzle.

9.

On

early model (Figure50) injection pumps, remove

capscrew and install valve spring and capscrew

with gasket. Torque capscrew to

75

to

89ft-lb.

(102-120

Nm).

10.

On late model (Figure

49)

injection pumps,

remove delivery valve capnut and holder to install

spring. Before installing delivery valve spring,

push delivery valve back onto its seat using your

little

finger. Install spring and valve holder.

If

the spring

is

not seafedprop-

eriy the valve holder can be

tightened only about one-fourth of the way down.

When fhe spring is properly seated the valve

holder can be tightened about fhree-fourths of

the way down by hand. Make certain that the

spring

is

seated properly in the valve holder and

on fhe delivery valve before torquing.

Torque valve holder to

70

to

75

ft.-lb.

(95

to

102

Nm). Loosen valve holder and retorque to

65

to

70

ft.-lb.

(88

to

95

Nm). Install and torque capnut

with gasket to 50 to

55

ft.-lb.

(70

to

75

Nm).

Loosen capnut and retorque to

60

to

65

it.-lb.

(81

to

88

Nm).

49

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INJECTION

PUMP

INSTALLATION

Be sure the steel shims between the pump and the

cylinder block mounting are the same. These shims

maintain proper gear backlash. The numberstamped

on the cylinder block injection pump mounting pad

indicates the proper shim thickness. This thickness

does not change when a new pump is installed.

It

changes only when a new cylinder block is installed.

1.

Turn engine in direction

of

rotation (clockwise

when viewed from the front of engine) until

number one cylinder is on a compression stroke

and the

PC

mark on flywheel lines up with timing

pointer on gearcase (Figure

52).

Rotation clock-

wise also takes out all gear backlash

in

that

direction.

Look into injection pump mounting hole to verify

that one intake lobe points outward and down

45

degrees.

2.

Remove screw (Figure

55)

on side of injection

pump. Rotate drive gear until a

0.125

inch

(3.175

mm) brass rod can be inserted into drivegearslot.

This locks the gear in position when installing

injection pump on engine.

3.

With injection pump drive gear locked, place

pump

in

mounting hole. Hold pump firmly against

cylinder block.

A

slight spring pressure indicates

that the pump and camshaft gears are meshed

(Figure

56).

J

PUMP

PUMP

m

1.171

INCH

-

INSTALLED

DIMENSION

PUMP

TAPPET

LIL

u

8406

FIGURE 56.

PUMP

INSTALLED

ROTATE

GEAR

UNTIL

BRASS

ROD

SLIPS

INTO

PLACE,

LOCKING

GEAR

4.

If

gears mesh, secure pump using a flat washer,

lock washer, and nut on each stud. Torque nuts

evenly to

15

to

16

ft.-lb.

(20

to

22

Nm).

5. Remove brass rod and install timing hole washer

and screw.

ROD

FIGURE

55.

LOCKING

THE

DRIVE

GEAR

50

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BRYCE/KIKI

FUEL

SYSTEM

The Bryce or

Kiki

fuel injection system (Figure57) is

located near the center on the left side of the engine

crankcase on

MDJE

engines. The pump is mounted

on an adapter casting. Two lobes of the cam shaft

operate the pump plungers, one plunger and cam

lobe for each cylinder. The fuel is pumped at high

pressure by

the

plungers through the delivery valves

The Bryce/Kiki injection pumps operate on the same

pumping and metering principles as the American

Bosch PLB pump described earlier in this section.

Fuel control from idle to maximum speed and power

is accomplished by rotating

the

helix on each pump

plunger. Both pump plungers and barrel assemblies

are rotated

(0

to 180 degrees) by a fuel control arm,

yoke, and a rack gear. Rotating the reciprocating

plunger changes the effective length of the plunger

strokes, and hence, the amount of fuel

it

delivers to

the injection nozzle.

The fuel transfer pump and

the

primary and secon-

dary fuel filters in this system are identical to those

described for and used on the other DJ-series

engines.

4

to the injection nozzles. FUEL RETURN

(FLEXIBLE LINE) GOVERNOR

POST

ARM ASSEMBLY

HIGH

PRESSURE LINES

FIGURE

57.

FUEL LINES

TO

INJECTORS

Nozzles

The

MDJE

fuel injection system uses either a Diesel

Kiki or

C.A.C.

throttling-pintle type nozzle. The noz-

zle

holders are either Yanmar of Diesel Kiki and have

a plated nozzle retaining nut that distinguishes them

from Bosch nozzle holders, which have a black oxide

finish.The nozzle tipsare interchangeable in Kiki and

Yanmar holders, but internal components of these

holders are not interchangeable. The opening pres-

sure for new nozzles should be

2100

to 2200 psi

(14480-15169 kPa).

High Pressure Injection Lines

Both high pressure fuel lines between the injection

pump and the two nozzles are designed to be installed

without any bending. Lines that fit on Bryce pump

installtions also fit on Kiki pump installations, and

vice versa. Whenever the lines must be removed, dis-

connect both ends. Do not bend the lines.

Bleeding Fuel

System

After replacing or cleaning the filters, bleed the fuel

system of air. Bleed air from fuel system as follows:

1.

Disconnect fuel return line at the tee near the

transfer pump. Use container to catch fuel.

2.

Operate hand priming lever on diaphragm type

fuel transfer pump until there are no air bubbles in

fuel flowing from the fuel return

line,

Figure

58.

If

fuel tank is disconnected, use

a

separate container

of

fuel

and connect

a

short hose line between the transfer pump inlet

and the fuel container. The pump has enough suction to pull

the fuel out

of

the container.

PRIMING

LEVER UNTIL

FUEL FLOWS FROM

RETURN LINE OF

INJECTION PUMP

FIGURE

58.

BLEEDING FUEL

SYSTEM

If

the camshaft transfer pump lobe

is

up,

crank engine one

revolution

to

permit hand priming. When finished, return

priming lever inward (disengaged position)

to

permit normal

pump operation.

3.

Connect the fuel return line at tee.

A

diesel engine cannot tolerate

dirt In the fuel system.

Dirt

is

one

of

the major causes

of

diesel engine failure.

A

tiny piece

of

dirt

in

the injection system may

stop

your unit. When opening any part

of

the fuel sys-

tem beyond the secondary fuel filter, place

all

parts

in

a

pan

of

clean diesel fuel as they are

removed. Before insfalling new

or

used

parfs,

flush

them thoroughly with clean fuel and

insfall

while

still

wet.

51

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BRYCE/KIKI FUEL INJECTION PUMPS

The Bryce/Kiki Injection Pumps aresimilar in design,

appearance, and performance, Figure

59.

Both units

mount two plunger and barrel assemblies in asingle

housing and use a common rack (gear) to rotate the

control sleeves and regulate the fuel output of both

pumps. Although the pumps are interchangeable on

the

MDJE

engines, internal components of the Bryce

and Kiki Pumps are not interchangeable. One exter-

nal difference is that the Bryce Pump uses an align-

ment dowel pin to fit

it

on the adapter assembly.

The delivery valves on both pumps are also similar,

but the Bryce has one copper sealing gasket whilethe

Kiki uses a combintion sandwich type seal that

requires a special deliveryvalve pulling tool to remove

it.

Both pumps use roller type tappets as cam followers,

which are held

in

place by pins and lock wire. Each

pump has an air bleed fitting to vent air and permit

easy priming.

RACKNOKE

KNOB

CONTROL

RACK

I

SHIM

Removal

If the rest of the fuel system is in working order and

fuel deliveryabnormal, remove the pump for replace-

ment

or

repair.

*

1.

2.

3.

4.

5.

6.

7.

Locate injection pump on service side of engine,

and remove necessary sheet metal and hardware

to make pump accessible.

Remove fuel inlet and return line, Figure

57.

Remove high pressure lines between pump and

injector nozzles (both ends).

Cap all lines and fittings, using extreme care to

keep all fuel system components clean.

Remove four socket head screws holding pump

to adapter assembly.

Position fuel control shaft and yoke as shown in

Figure61. Then, lift pump off of adapter assembly.

Carefully clean injection pump assembly and

place

it

in a clean place. Retain shims between

pump and adapter, as they are needed for

reassem b

I

y.

INJECTION PUMP ADAPTER

The cast iron adapter (Figure

60)

is

the

crankcase

mounting fixture for the fuel injection pump and its

fuel control arm, yoke, and overfueling control

device.

A

composition gasket is used between the

adapter and the crankcase.

Thefuel control arm and theshaft and yokeassembly

transmit governor action to the injection pump con-

trol rack. The overfueling device provides maximum

(excess) fuel during engine starting and limits the

maximum amount of fuel and engine power output to

protect the engine from excessive loading.

Do

nof change the adjusfmenf of

Ezx

this device unless absolutely re-

quired. The warranty may be voided if the fuel stop

is

infenfionally altered to increase engine power above

70

percenf overload af rafed speed and load.

CAUT,ON

FIGURE

59.

INJECTION PUMP

FUEL

CONTROL

ARM

GASKET

I

Repair

Most fuel system troubles are not due to a faulty

injection pump; test the rest of the fuel system before

condemning the injection pump.

Onan discourages field repair of the injection pump

because of the exceptionally close tolerances be-

tween parts and because of the need for the special-

ized equipment necessary for repair. The injection

pump is an expensive part of

the

unit, and even a

particle of dirt as fine as talcum powder could score

its working surfaces.

-

ADAPTER

FIGURE

60.

ADAPTER ASSEMBLY

52

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SHAFT

POSITION

OF

FLAT

FOR

REMOVING AND

. INSTALLING PUMP

TO

ADAPTER

TOP END

FUEL PLUNGER

DO

NOT CHANGE

EXTERNAL

ASSEMBLY

RETAINING LOCK NUT

DOWEL PIN

ADA~TER

MOUNTING

BOLT HOLES (4)

PUMP MOUNTING

HOLE

"OLE'

(4)

(BRYCE ONLY)

FIGURE

61.

INJECTION

PUMP

ADAPTER

ASSEMBLY

I

E-

LE

LE

PRESS

DOWN

TO

88

1"

'h

c=

T"f

REMOVE

BEARING

DRIVER

4XJ-0376

SEAL SPACER BEARING SPACER

SLEEVE

SLEEVE

FIGURE

62.

BEARING

INSTALLATION

AND

TOOL

PACKAGE

(420-0374)

A

diesel engine cannof tolerate dirt

in the fuel system.

Dirt

is one of the

major causes of diesel engine failure.

A

tiny piece

of

dirt in fhe injection system may stop your unif. When

opening any part of fhe fuel system beyond the

diesel fuelas they are removed. Before installing new

orusedparts, flush them thoroughly, andinsfallwhile

sfill wet.

secondary fuel filter, place all parts in a pan of clean

Bearing and Seal Replacement Procedure

After

adapter bly

has

been

removed from

the

engine, replace the bearings and seal on the yoke

shaft as follows:

Removal

1.

Remove fuel control arm.

2.

Remove four mounting bolts and

lift

adapter,

assembly

off

of engine block.

It

may be necessary

to tap assembly with lead or plastic hammer

in

order to loosen adapter from gasket.

3.

Discard old gasket and clean area on engine

block.

A

new gasket is required for reassembly of

adapter to prevent oil leaks.

1.

Referring to Figure

62,

press shaft and yoke

assembly towards center of adapter until shaft

and bottom bearing slips

out

bottom end.

2.

Using solid end of bearing driver, press top bear-

ing and seal out bottom end.

3.

Remove external retaining ring and slide bearing

off

yoke shaft.

4.

Thoroughly clean and oil yoke and shaft assem-

bly and adapter for installing new bearings and

seal.

5.

Install bottom bearing from top of adapter cast-

ing, using hollow end of bearing driver. Makesure

"lettered" side of bearing faces upward and that

tool bottoms against top

of

adapter boss.

6.

Slide yoke and shaft assembly up through bear-

ing,

then

support

yoke and shaft assembly

for

installing the retaining ring.

4.

Thoroughly clean adapter assembly before re-

5.

Place adapter assembly in suitable holder for

Do

not clamp in a vise unless

machined surfaces are protected

placing new bearings and oil seal.

removing and installing bearings and seal.

from damage by thejaws of the vise.

53

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7.

Using hollow end of bearing driver, press retain-

ing ring on shaft, far enough

so

ring snaps into

groove on shaft.

8. Slide bearing spacer sleeve (shortest sleeve) over

hollow end of bearing driver; then use tool to

press top bearing into adapter. Make sure tool

bottoms against top of adapter boss and that "let-

tered" side of the bearing faces upward.

9. Replace bearing spacer sleeve with seal spacer

sleeve (longest sleeve) and then use tool to press

oil seal over shaft at top of adapter. Make sure

seal is installed with "lettered" side down, facing

the bearing, and that tool bottoms against top of

adapter boss.

10.

Reinstall adapter and injection pump assemblies.

GASKET

I

ADAPTER

\

*--

BLOCK

WALL

FIGURE

63.

MEASURING

DEPTH FOR SHIM THICKNESS

Installation

Proceed as follows:

1.

Place new gasket

on

engine block dowel pins and

install adapter using four socket head screws and

lock washers; torque screws to 20 to 24 ft.-lb. (27

to 33 Nm).

2.

Determine shim thickness required between

pump and adapter, because the new gasket may

not be the same thickness as the original one. See

Figure 63.

3.

B.

Using

a

depth micrometer, measure the dis-

'tance from the mounting face of the adapter

to the base circle of either cam lobe.

The shim kit contains shims in the following thicknesses:

0.002,0.003,0.006,0.010,0.014,

and

0.018

inches.

If

one

shim isnotenough, the required shim thickness(between

0.004

and

0.020)

can be obtained within

0.001

inch by

combining

two

of

the above shims. The thickness in

inches is stamped on each shim. For the greatest accu-

racy, measure the total shim thickness with a micrometer.

4. To calculate the shim thickness, determine the

following:

Standard installation depth

Distance from adapter flange to cam

of pump is .

.

.

. .

.

. .

.3.2598* inches (82.8 mrn)

lobe base circle as measured

(subtract from above)

-

inches

(

Required shim mrn)

thickness=

-

* Manyearlierspec

AB

MDJEengines have an instal-

lation dimension

of

3.2540 inch (82.652 mm). On

these units, a silkscreen print indicates this dimen-

sion. If

so,

3.2540 should be substituted for 3.2598 in

Step 4.

INJECTION

PUMP

INSTALLATION

Install injection pump on adapterassemblyasfollows:

1. Rotate crankshaft to position camshaft

so

that the

pump rollers contact the camshaft base circle

(low point of the pump cam lobes). One lobe

should be up, the other lobe down. See Figure63.

2. Using proper shim thickness (Figure 64), install

pump to adapter with four socket head capscrews

and lockwashers. Torque to 20 to 24 ft.-lb. (27 to

33 Nm).

Be sure the controi rack bail fits

between the yoke fingers for

proper operation. If the

rack

ball is not properly

placed in the yoke, engine operation

will

be

uncontrollable and must be stopped immediately.

In

such as emergency, the engine can be stopped

by blocking the air intake,

or

by loosening

(just

cracking) the fueiinjector line fittings at the pump

The proper shim thickness is

stamped

on the block for the

lation

of

the injection pump.

end.

shim combination required during the original factory instal-

3. Connect flexible fuel inlet line to pump inlet.

To

measure for shim thickness:

4.

Connect each high pressure fuel line to proper

pump outlet and nozzle inlet.Torque nuts to

16

to

A.

Rotate crankshaft to position injection pump

cam lobes on the camshaft in a vertical posi-.

tion

so

the base circle of each lobe faces the

adapter opening.

18 ft.-lb. (22 to 24 Nm).

5.

Reinstall fuel control arm on yoke and shaft

assembly, Figure 64. Tighten socket head screw,

but

do

not over tighten.

54

Redistribution or publication of this document, 

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FIGURE

64.

PUMP AND ADAPTER

ASSEMBLY

6.

Adjust fuel solenoid plunger

so

that a

0.010

to

0.030

inch

(0.25

to 0.76 mm) clearance exists (see

Figure65) between the plunger adjustment screw

and the fuel control arm with the solenoid

in

de-

energized position.

To

adjust the plunger length,

hold the plunger and adjust the screw on the

plunger lever pin at the fuel shutoff position.

Retighten locknut.

occur at 18"

BTC

+4"

on

MDJE

engines. If piston

drop is measured to determine the PC point, the nom-

.

inal value is

0.1

15

inch (2.9 mm); the allowable range

is 0.171 to 0.070 inch

(4.3

to 1.8 mm).

FUEL

CONTROL

CLEARANCE

0.010-0.030

INCH

(0.25-0.76

mm)

FIGURE

65.

FUEL SOLENOID ADJUSTYEW

Flow

Timing

-

Troubleshooting Only

Flow timing is performed at either injection line to

establish

or

confirm the port closing (PC) point

of

each fuel injection cycle. The PC point should be

about

the

same for each cylinder, but an allowable

difference between cylinders is

2.5

crankshaft

de-

grees of rotation, measured

on

the flywheel rim.

Approximately 0.1-inch

(2.54

mm)

is

equivalent to

1

degree

of

rotation.

At

1500

and

1800

rpm, PC should

t

DELIVERY

PIPE

DELIVERY VALVE

DELIVERY

VALVE

HOLDER

DELIVERY

VALVE

PUMP

HOUSING

SUCTION

CHAMBER

PORT

PLUNGER BARREL

KNOCK

PIN

UPPER

SPRING

PLUNGER

SPRING

CONTROL

SL&E

LOWER

SPRING

SEAT

GUIDE

PIN

FIGURE

65a.

SINGLE INJECTION PUMP ASSEMBLY

55

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Flow

Timing Procedure

To

determine PC, proceed as follows:

1.

Remove one high pressure line (both ends), and

the corresponding delivery valve holder, spring,

volume reducer, and delivery valve, Figure 65a.

Leave gasket and seat in pump.

Place the spring and volume reducer in a clean container

of

fuel until re-installed.

2. Re-install delivery valve holder (without spring

and volume reducer).

3.

Install high pressure line

on

delivery valve outlet

so

that drops of fuel can be easily counted and

collected in a receptacle at the open end

of

the

line.

4.

Move the fuel control arm toward the front of the

engine to full fuel range.

The fuel solenoid must be energized or held (blocked) to keep

the plunger

out

of the way.

5.

Manually operate transfer pump lever to provide

fuel pressure to injection pump.

6. Rotate flywheel clockwise very slowly by hand

until fuel stops flowing from open line, even

though transfer pump operation is continued.

7. Rotate flywheel counterclockwise until fuel flows

freely; then, clockwise very slowly to position

where fuel drops can be counted at one drop per

second with the transfer pump operating.

This is the PC point;

it

should be marked on the flywheel

opposite the timing pointer.

8.

After flow timing iscompleted, remove high pres-

sure line and delivery valve holder; then, reinstall

delivery valve, spring, and volume reducer.

Make sure all parts are

clean.

9. Reinstall delivery valve holder and torque Bryce

holder to 29 to 33 ft.-lb. (39 to 44 Nm). Torque

Kiki holder to

44

to 47 ft.-lb.

(60-64

Nm). If fuel

leakage occurs, replace the delivery valve gasket.

10.

Reinstall high pressure line between pump and

nozzle.

11.

Using the same procedure, flow timing can be

performed on the other cylinder to determine PC

or the difference in degrees between cylinders;

2.5 degrees is allowable.

Torque Instructions

The following torque instructions are for Bryce/Kiki

Injection Systemson Onan MDJE Engines, Figure66.

Bryce Pump Model FAOBR070E0686

Kiki Pump Model NP-PFR2K70/1NP22

and

1

NP23.

0

Delivery Valve Retainer

Bryce: 28.5 to 32 ft.-lb. (39 to 43 Nm)

Kiki: 43.5 to 47 ft.-lb. (60 to 64 Nm)

When using a new deliveryvalvegasket

on

Kiki

pumps,

tighten the

valve

lo

full torque value and loosen twice; then, torque retainer a

third time to seat the gasket finally.

0

Fuel Inletstud (both)

15

to18ft.-lb. (20to24Nm).

0

Bleed Fitting Retainer (both) 35 to 52 Ib. inch (47

0

All

Adapter

&

Pump Mounting Screws 20 to 24

to

7.0

Nm).

ft.-lb. (27 to 33 Nm).

FUEL

CONTROL

ARM

SHAFT

BLEED

FITTING

(RESTRICTED)

fl/

INJECTION

PUMP

INLET FITTING

DELIVERY

VALVE

RETAINER

SHIMS

T

HIGH

PRESSURE

LINE

CONNECTION

5/16

x

18

SOCKET

HEAD

SCREWS

WITH

LOCKWASHERS

(8

EACH)

Engine Performance

Engine performance

at

1500

and 1800 rpm varies

within acceptable limits when

PC

occurs between

14' and 22' BTC. Generally, retarded timing results

in lower smoke but higher fuel consumption; and the

opposite is the case when timing is advanced.

FIGURE

66.

BRYCWKIKI

PUMP AND ADAPTER ASSEMBLY

56

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TROUBLESHOOTING

PUMP

PROBLEMS

Normally, little goes wrong with the injection pump

after

it

is installed on the engine as long

as

timing

is

correct and clean fuel is used continually.

The

most

common problem is caused

by

a

delivery

valve that may be held open by dirt or metal chipsthat

entered the pump

or

fuel system during assembly and

installation.That is the reason protectivecovers must

be used to keep foreign matter out of unassembled

fuel system components.

If the pump is suspected of causing misfires or poor

operation:

0

Check the temperature of each nozzle holder and

exhaust port; the coolest cylinder is the faulty

one.

Fuel penefration

of

the skin

might cause severe personal

injury.

Do

not

let the nozzle high-pressure fuel

spray

against skin

surfaces.

Loosen (crack) the high pressure injection lines,

one cylinder at a time (like disconnecting a spark

plug wire), to determine the faulty cylinder; the

cylinder that looses the least power is misfiring,

or not firing.

Pump disassembly

by

unqualified personnel

is

not authorized

and may void the pump warranty.

Return all faulty pumps

to

the Onan factory for repairs, or

replacement

if

still

under

warranty.

Otherwise,

refer all Ser-

vice

problems

to

authorized

B~yceRucas

and

Diesel

Kiki

ser-

vice centers.

THROTTLING PINTLE NOZZLE TESTS

The following tests will determine nozzle conditions

using a manually operated test stand. Each nozzle

must be removed from the engine for testing. Prior to

testing, each nozzle must be cleaned, decarboned,

and inspected, as described for non- throttling pintle

type nozzles earlier

in

this section. New or recondi-

tioned nozzles must be thoroughly cleaned in cleaning

solvent or test oil to remove

all

traces of preservative

grease before testing.

Visual

Check

Using illuminated Magnifier:

1.

Inspect nozzle valve for damaged

or

rough seat.

2.

Inspect pintle for wear, damage, or out-of-round

3.

Check nozzle body for damaged or carboned

spray hole.

seat.

Slide

Test

oil.

1.

Dip clean nozzle valve

in

filtered diesel fuel or test

2.

Insert valve in nozzle body, Figure

67

3.

Holding body almost vertically, puli valve out to

one-third of its engaged length; then release

valve.

4.

The released valve (becauseof its weight) should

slide down to its seat.

The nozzle valve and nozzle

body

are

lapfitted

together and must

not

be

interchanged.

57

Redistribution or publication of this document, 

by any means, is strictly prohibited.

FIGURE

67.

SLIDETEST

Testing Nozzles with

Hand

Operated Tester

The proper tester can be used to check opening pres-

sure, leak-down rate, chatter, and spray pattern.

Install cleaned and inspected nozzle in tester and

proceed as follows:

1.

Place nozzle in holder.

2.

Tighten nozzle nutfingertight, then using proper

size wrench, tighten nut to45 to

50

ft.-lb.

(61 to68

Nm).

3.

Connect delivery line between nozzle holder and

test stand; be sure that fittings match properly.

4. Test nozzle for jamming:

A.

Bypass pressure gauge.

B.

Press nozzle tester hand lever down quickly

so

that nozzle opens

6

to

8

times per second.

C.

Nozzle should chatter with a shrill whistling

sound, if valve moves properly.

Fuel

penetrirffon

of

the

skln

might

cause severe personaiinjury.

Do

not

let fhe nozzle high-pressure fuel

spray

against

skin

surfaces.

A

KlKl

CAPNUT

Lu

ADJUSTING

SCREW

-

LOCKNUT

-SPRING

MERICAN-BOSCH

FIGURE

68.

NOZZLE ADJUSTMENT

KlKl

NOZZLE

ADJUSTMENT

If the opening pressure is incorrect, connect nozzle

to a tester and hold the nozzle

in

a suitable holder

or

smooth jaw vise.

1.

Remove cap nut, Figure

68.

2.

Loosen locknut.

3.

Turn adjusting screwto desired opening pressure.

4. Tighten locknut to

45

to

50

ft.-lb.

(61

to

68

Nrn).

5.

Tighten cap nut

to

45

to

50

ft.-lb.

(61

to

68

Nrn).

6.

Remove nozzle from tester and holder.

YANMAR-AMERICAN

BOSCH

NOZZLE

ADJUSTMENT

If

the opening pressure is incorrect, connect nozzle

to tester and hold nozzle in a suitable holder or

smooth jaw vise.

1.

Remove plug from cap nut, Figure

68.

2.

Loosen locknut.

3.

Turn adjusting screw to desired opening pressure.

4.

Tighten cap nut to

45

to

50

ft.-lb.

(61

to

68

Nm).

5.

Install plug using a thread sealant.

6.

Remove nozzle from tester and holder.

58

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OPENING

PRESSURE

The correct opening pressure should be 21 00-2200

psi

(14480-15169

kPa)

for

new

nozzles.

It

may

be

about

200

psi (1380 kPa) less after the nozzles have

operated a few hundred hours. Open pressure gauge

to obtain reading.

Leakage Test

1.

Slowly depress hand lever until nozzle test gauge

indicates 285 psi (1966 kPa) below specified

opening pressure.

2. Consider nozzle leak-proof if no fuel (not even

one drop) emerges from nozzle tip within

10

seconds.

Chatter Test

Operate hand lever downward (1 or 2 nozzle

opening cycles per second) until nozzle ejects a

stream of fuel with a soft chattering sound.

Take pressure readings from gauge.

Slightly increase hand lever movements (2 or

3

nozzle opening cycles per second), the stream

velocity should increase and create a hissing

sound.

Accelerate lever movements to4 to

6

nozzle open-

ing cycles persecond.The nozzleshould createa

shrill whistling sound and a spray pattern.

SPRAY PATTERN

The spray pattern must be compact and well atom-

ized at full

lift

to be correct. The pressures between

nozzle opening and full

lift

causes the fuel to emerge

in a stream, changetoflag-likeformations, and finally

reach atomized spray pattern at full lift, with lever

movements producing 4 to

6

nozzle opening cycles

per second. See Figure

69.

Closed

FIGURE

BLEEDING

FUEL

SYSTEM

Bleed fuel system whenever the filters are changed or

when

there

is

air

in

the

lines.

Procedure:

Manually actuate fuel transfer pump until air bubbles

are all out and clear fuel flows from the bleed valve

automatically, Figure

70.

If

the transfer pump cam lobe

is

on the high side, the priming lever

will

not operate the pump. Rotate the flywheel one revolution

before

operating the priming lever.

BLEED

VALVE

FUEL

RETURN

CONNECT

FIGURE

70.

BLEEDING FUEL SYSTEM

PREHEATING

CIRCUIT

This 12 volt battery circuit consists partly of manifold

heaters that raise the combustion air temperature at

the intake manifold and a glow plug in each cylinder

that heats the precombustion chamber for engine

starting, Figure 71. The manifold heater and glow

plugs are wired in parallel and are controlled by a

preheat switch on the control box.

GLOW PLUG

MANIFOLD

HEATER

FIGURE

71.

GLOW PLUG AND MANIFOLD HEATER

Slightly

open

(pilot spray)

69.

NOZZLE

SPRAY

ACTION

59

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Governor

System

The purpose of the engine governor

is

to maintain a

constant engine speed during changes in power

demands.

A

governor responds to changes in power

demands by varying the throttle position.

A

constant-

speed governor is standard on marine engines.

GOVERNORS

The constant-speed governor maintains enginespeed

up to

2400

rpm. The speed-sensing device is a ball

and cup mechanism on the camshaft gear. A yoke,

resting on the cup, is connected to the throttle lever.

Any change in engine speed is transmitted from the

cup to the yoke, and on to the throttle.

Tension on thegovernor spring determines thespeed

at which the engine is controlled. Astud screwed into

thespring isused tovarythenumberofeffectivecoils

for getting the desired sensitivity-the speed drop

from no-load to full-load.

Maintenance

Periodically lubricate the metal governor Iinkagewith

lubricating graphite or light non-gumming oil. Also,

inspect the governor linkage for binding or excessive

slack or wear. Plastic ball joint socket does not need

lubrication.

Adjustments (MDJB, MDJC, MDJE, and MDJF)

Prior to Spec

R,

both the governed speed and the

governor sensitivity are adjusted with the stud and

nut on the front of the engine (Figure72). Beginning

Spec

R,

the sensitivity is adjusted with an adjusting

ratchet.

Speed Adjustment

(Prior

to

Spec

R):

To

adjust the

governed speed, hold

the

governor spring stud in

position and turn the governor spring nut with a

wrench. For accurate speed adjustment, use a reed

frequency meter on the

AC

output.

(A

mechanical

tachometer is not as accurate.) On generator set fre-

quency and speed according to the nameplate.

Sensiflvity

Adjustment

(Prior

to

Spec

R):

To

adjust

the sensitivity, turn the governor spring stud; coun-

terclockwise gives more sensitivity (lessspeed drop).

If

the governor is too sensitive, a hunting condition

occurs (alternately increasing and decreasing speed).

Adjust for maximum sensitivity without hunting. See

the engine nameplate for speed and sensitivity set-

tings. After sensitivity adjustment, the speed may

require readjustment.

Speed

Adjustment (Begln

Spec

R):

Adjust engine

speed by turning governor speed adjusting nut (Fig-

ure

72).

Turn nut clockwise to increase speed, coun-

terclockwise to decrease speed.

TURN

TO

INCREASE RPM

(HOLD SPRING

STUD

IN

LTURN

FOR

MINIMUM

SPEED DROP. THEN

ADJUST

NUT-

GOVERNOR-

J/

SPRING

STUD

GOVERNOR

1

SPRING

NUT

(PRIOR

TO

SPEC

R)

GUVERNORARH

\/

’

GOVERNOR

GOVERNOR

YOKE

PEED ADJUSTING

NUT

SENSITIVITY

A

CUUSTlffi

RATCHET

(BEGIN

SPEC

R)

ARM

9

GOVERHOR

STUD

SENSTIVITY

FIGURE

72.

GOVERNOR ADJUSTMENTS

Redistribution or publication of this document, 

by any means, is strictly prohibited.

I

Sensitiwity

Adjustment

(Begin

Spec

R):

Adjust sensi-

tivity (no-load to full-load speed drop) by turning the

sensitivity adjusting ratchet nut.

If

speed drops

too

much when a full load is applied, turn the ratchet nut

counterclockwise. An oversensitive adjustment, ap-

proaching no speed drop when load is applied, may

result

in

hunting condition (alternate increase and

decrease

in

speed).

MDJA

Governor

System

Adjust engine speed

by

turning governor speed

adjusting nut (Figure

73

prior to

SPEC

R

and Figure

74

SPEC

R).

Turn nut clockwise to increase speed,

counterclockwise to decrease speed.

Adjust sensitivty (no-load to full-load speed drop) by

turning the sensitivity adjusting ratchet nut. If speed

drops too much when full load is applied, turn the

justment, approaching no speed drop when load is

applied, may result in a hunting condition (alternate

increase and decrease in speed). Adjust for maxi-

mum sensitivity without hunting. The use of a reed-

type frequency meter will give the most accurate

results. On generator sets, it should be possible to

adjust for a sensitivity of less than

3

hertz;

2

hertz is

usually attainable.

ratchet nut counterclockwise. An oversensitive ad-

FIGURE

74.

MDJA

(BEGIN

SPEC

R)

GOVERNOR ADJUSTMENTS

PUMP (HUL

D

SP

RI

NG

STUD

GOVERNOR SPRING

*-TURN

FOR

MINIMUM

.SPEED

DROETHEN

ADJUST NUT

ADJUSTMENT STUD

n1

\L/

TURN TO INCREASE R.P.M.

of

hole

in

governor

shaft.

A9

AND NUT

3-

FIGURE

73.

MDJA GOVERNOR

ASSEMBLY

(PRIOR

TO

SPEC

R)

.

61

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Oil

System

Onan diesel engines have pressure lubrication to all

bearing surfaces of the engine. The oil system in-

cludes an oil intake cup, a gear-type oil pump, a

by-pass valve, a full-flow oil filter and passages and

drillings through the block for oil delivery.

Figure

75

shows the pressure oil system.

A

thin film of oil from the crankcase lubricates the

cylinder walls, and the rings wipe the excess oil off to

prevent passage of oil to the combustion chamber.

The upper portion of the cylinders are partially lubri-

cated by the fuel. The connecting rod bearings are

critically in need of lubrication because of the high

pressures and high rotating speeds. Bearing lubrica-

tion and cooling are very important to the life

of

an

engine.

Normal oil pressure should be

25

psi

(172.5

kPa) or

higher when the engine is at operating temperature. If

pressure drops below

20

psi

(138

kPa) at governed

speed, inspect the oil system for faulty components.

OIL

PUMP

The oil pump is mounted on the front of the crank-

case behind the gear cover, and is driven by the

crankshaft gear.

The pump draws oil from the crankcase and delivers

it through the oil filter to the rocker housing, through

the crankcase drillings to the crankshaft bearings,

camshaft front bearing, crankshaft passages to con-

necting rod bearings and connecting rod passages to

piston pin bushings.

c

-FILTER

LS-1013

FIGURE

75.

OIL

PRESSURE

SYSTEM

Repair

Except for the gaskets, component parts of the pump

are not individually available.

If

the pump is defective

or excessively worn, replace it. Disassemble the

pump by removing the two capscrews holding the

pump coverto the body. Inspect forexcessive wear in

gears and shafts. To improve pump performance,

adjust the gear-end clearance by changing the gasket

thickness between the pump body and cover. Use the

thinnest gasket

that

permits free movement of

the

pumpshafts. Oil all parts when assembling the pump.

Removal

1.

Remove gear cover and oil base. (See

ENGINE

2.

Unscrew intake cup from pump.

3.

Remove crankshaft lock ring and gear-retaining

4.

Loosen

two

capscrews holding pump and remove

DISASSEMBLY.)

Installation

Before installing, fill the pump intake and outlet with

oil to be sure

it

is primed. Mount the pump on

the

engine and adjust the 0.005-inch

(0.127

mm) lash

between the pump gear and crankshaft gear. Mount

the intake cup

on

the pump

so

it

is

parallel to the

washer.

Pump-

bottom

of the crankcase.

62

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BYPASS

VALVE

Located

on

the outside of the rear bearing plate, the

bypass valve (Figure

76)

controls

oil

pressure

by

allowingexcessoil toflow directly backtothecrank-

case. Normally the valve begins to open at about 25

psi

(172.5

kPa).

It

is

non-adjustable, and normally

needs no maintenance.

To

determine if high oil pressure is caused by the

plunger sticking closed, or

low

oil pressure by the

plunger sticking open, clean

and

inspect the valve.

To

remove the valve, unscrew the recessed plug

in

the rear bearing plate and lift out the spring and

plunger assembly. Determine proper valve operation

by checking thespring and plunger against thegiven

values:

Plunger Diameter

.

.

. .

.

Spring

0.3365

inch

to

0.3380

inch

(8.5471

to 8.5852

mrn)

2-5/16

inches,

+

1/16

inch

(74.613,

+

1.588 mm)

2.225

Ib.

at

1-3/16

inches (compressed)

(1.01

kg) at

(30.163

rnm)

(compressed)

Free Length

.

.

. .

. .

.

.

FIGURE

76.

BYPASS

VALVE

CYL. HEAD

CY

L.

HEAD

3

AND

4

lAND2

4

CY

LINDER

ONLY

W

FLUSH ROCKER BOXOIL LINE

WITH FUEL

AND

CLEAN HOLES

WITH

FINE

WIRE.

Pjee

Note

2)

OIL FILTER

ADAPTER

I

1

J

ECTlON

PUMP PAD

Note

1

-Usea#70drill bit (.028in. [1.17

mm])

for cleaning being careful not to

enlarge hole.

These

are restricted flow

fittings. If holes are enlarged, valve deck

will receive excess oil. If

holes

are plug-

ged.valvetrain will rundryand wearout.

Note

2

-

Use a

#56

drill bit for cleaning

being careful not

to

enlarge hole.

It

is

critical that fittings be kept open.

If

restriction is plugged, injection pump

tappet, bottom, and plunger will wear

out.

FIGURE

77.

CLEANING

ROCKER BOX OIL LINE AND RESTRICTION ORIFICES

63

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OIL LINES

At overhaul time the rocker box oil line should be

flushed with fuel and a fine wire used to clean the

small holes, Figure

77.

Clean standpipe breather on

four cylinder engines.

Clean out all other oil lines and drillings with com-

pressed air whenever the engine is disassembled or

overhauled. The oil gauge passage may be reached

by removing the oil filter mounting plate.

External oil lines, the rocker box oil line, and the

internal oil line to the rear bearing are replaceable.

Restriction orifices are placed

in

theexternal oil lines

to regulate the quantity of oil delivered to the injec-

tion pump gearing and tappet and to the rocker arm

and valve train areas. Two orifices are located

in

the

Tee fitting at the injection pump, and one orifice is

located in the inlet fitting to each cylinder head.

To

prevenf injection pump or valve

train damage from lack of iubrica-

fion,

ensure fhaf ail restriction orifices are kept open.

Cleaning can be done using

a

fine wire or drill bit and

compressed air.

0.028 inch size at heads

(0.71

mm)

0.046

inch size at Tee

(1

.I

7

mm)

OIL FILTER (Full Flow)

The oil filter is mounted on the filter plate at the left

side of crankcase (Figure78). It requires replacement

every 200 hours of normal operation. Remove filter by

turning counterclockwise, using a filter wrench.

Install new filter finger-tight plus

1/4

to

1/2

turn.

FILTER

FIGURE

78.

FULL FLOW OIL FILTER

Hot crankcase

011

can cause burns if

if is spilled

or

splashed on skin.

Keep flngers and hands clear when removing

fhe

oil

filter and wear profecfive clothing.

CRANKCASEBREATHER

'

MDJA Begin Spec

R,

MDJB Begin Spec

S,

and

MDJE

These engines are equipped with a ball check valve

for maintaining crankcase vacuum. The only mainte-

nance required is to clean the components periodi-

cally. Remove the hose clamp, breather hose, and

breather cap clamp to release the breather cap and

valve assembly. Wash cap and valve assembly and

the baffle in suitable solvent and reinstall.

CAP

AND

VALVE

BREATHER TUBE

FIGURE

79.

CRANKCASE BREATHER

AMP

CRANKCASEBREATHER

MDJC, MDJF Begin Spec

T

These eng

i

nes are equ

i

pped with a crankcase breather

pipe that vents c,rankcase fumes directly from the

rocker box coverto the cylinder head intake port (see

Figure 80). The crankcase breather pipe must be

removed and cleaned after every500 hours of engine

operation.

A

clogged breather pipe may result in oil

leakage at the rocker box gaskets and oil filter seal.

ROCKER

COVER

CYLINDER HEAD

FIGURE

80.

CRANKCASE BREATHER PIPE

64

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by any means, is strictly prohibited.

CRANKCASE BREATHER

.

MDJA

Prior

to

Spec

R

The crankcase breather is located

in

the left rear

corner

of

the crankcase and maintains

a

partial

vacuum in the crankcase during engine operation. Its

purpose is to ventilate the crankcase and control oil

loss.

It

consists of a metal filter packed

into

the tube

on the crankcase, a rubber cap with flapper valve, and

a

hose connecting it to the engine air horn.

To

disassemble, remove the rubber cap from the

crankcasetubeand prythevalveoutofthecap. Wash

the valve in fuel at regular intervals and, if defective,

replace

it.

At

the same time, pull the baffle out of the

breather tube and clean

it.

Install the valve with the

perforated disk toward the engine. Figure

81

shows

the crankcase breather.

BREATHER TUBE

FIGURE

81.

CRANKCASE BREATHER

PULSATION DAMPER

MDJC

Begin

Spec

S

and

MDJF

These enginesareequipped with a pulsation damper

which serves two major functions.

It

dampens pulsa-

tions which originate in the intake manifold and

which contribute to oil carry-over.

It

also acts as an oil

separatorto condense oil vapor and small oil droplets

(in the blowby fumes) to prevent them from getting

into the intake manifold and combustion chamber.

OVERFLOW

HOSE

OIL

DRAIN

FIGURE

82

PULSATION DAMPER

OIL

PRESSURE GAUGE

Some engines have an oil pressure gauge. If faulty,

replace

it.

Remove with a wrench and install

a

new

gauge. Check for a plugged oil passage.

The nonadjustable oil pressure switch controls the

decompression solenoid

in

the starting system,

allowing it to energize only when the switch closes.

This allows theengine

to

build upspeed, during start-

ing, before compression occurs. The switch closes at

about

5

psi

(35

kPa) under increasing oil pressure.

This is not a lowoilpressure profec-

.

fion swlfch.

If

will not profecf the

engine against slowly decreasing oil pressure.

On

MDJA

engines

if

the decompression switch does not energize,

check switch operation. Short the switch to ground when the

engine has built

up

speed during starting. The governor solenoid

should energize immediately and the engine should

start.

When fhe engine starts, check im-

mediafely for oil pressure. Shuf fhe

engine down iiollpressure does nof build up within a

few seconds. in this case, the lack

of

oil pressure

is

causing iaulfy operation, not fhe swifch.

65

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mm

WEIGHTS

LOW

OIL

PRESSURE

CUT-OFF SWITCH

The switch (Figure 83)

is

located on the oil filter

adapter plate below the oil filter. Aspecial start switch

jumpers

the

cut-off switch during starting to allow

engine to build up oil pressure and close the switch.

The switch closes at 13 to

15

psi (90 to 104 kPa),

under increasing pressure. If oil pressure falls below

13 psi

(90

kPa), the switch opens.

IRE

FIGURE

83.

LOW OIL PRESSURE SWITCH

CENTRIFUGAL

SWITCH

This switch (Figure 84)

is

mounted on the gear cover

backplate and operates directly

off

the camshaft

gear. Normally open, the switch closes when engine

speed builds up to about

900

rpm. This allows the

engine

to

build up sufficient oil pressure

so

that

it

can

be started.

For correct operation, maintain the switch gap at

0.020

inch (0.51 mm). See Figure

85.

Check the contacts for dirt

or

pitting when adjusting

the

gap.

Clean the contacts with paper or replace if

they are badly pitted.

A715

u

FIGURE

84.

CENTRIFUGAL SWITCH ASSEMBLY

Disassembly

1.

2.

3.

4.

5.

Disconnect the battery

to

prevent accidental

shorts.

Remove the switch cover, to reveal the point set.

Remove the point set assembly by removing the

screws holding

it

to the plate. Pull out the plunger

and plunger diaphragm.

Remove the centrifugal switch plate,

to

reveal the

cam and weight assembly.

Pull out the cam and weight assembly.

Be

carefulnot

to

lose thespacer

mounted

on

the gear shaft

behind the gear.

CENTRIFUGAL

FIGURE 85. BREAKER POINTS

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Repair

Thoroughly clean the gear and cam assembly, the

bearing surfaces

in

the gear case and breaker plate,

and the oil trickle holes to these bearings. Check the

oil spray hole in the gear case to be sure

it

is open.

Check for wear in the spacer, fiber plunger, and the

spring loaded shaft plunger. The spacer must be at

least

0.35

inch

(8.89

mm) long.

If

it

is not, replace

it

immediately. Push the weights outward; they should

move freely. If they do not,

or

if any part of the assern-

bly

is

sticking or worn, replace the cam and weight

assembly.

If

the cam

is

loose

on

the gear

shaft,

replace the assembly.

If

the breaker gap cannot be maintained at

.020

inch

(0.51

mm), check the fiber plunger and spacer for

wear.

Assembly

1.

Install thespacer on the shaft and install the shaft

assembly into the gear case, Match

it

with the

cam gear.

2.

Install the spring and plunger into the end of the

shaft.

3.

Install the breaker plate.

4.

Install the plunger and diaphragm.

5. Install the breaker pointson the breaker plateand

6.

Install the switch cover and reconnect the battery.

set the gap at

0.020

inch

(0.51

mm).

67

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Starting

System

These models use a separate

12

volt starting motor

mounted on the right hand side of the engine to drive

the flywheel.

It

is a standard automotive starting

motor with a solenoid for engaging the pinion and an

over-running clutch.

When

the solenoid is energized,

its core pulls in, shifting the pinion into engagement

with the flywheel ring gear.

At

the same time, con-

tacts in the solenoid close to provide a circuit for the

starter motor. The starting motor remains engaged

until the starting switch

is

released.

If

engine

is

equipped with a start-disconnect switch, the starter

motor will automatically disengage flywheel gear when engine

speed reaches

about

900

rpm.

The starter is protected from over-speed by an over-

running clutch which permits theengine to run faster

than the starter before

the

pinion

is

disengaged. Fig-

ure

86

shows the starting circuit.

MAlNTENANCE

Periodically check thestarting circuitwiring for loose

or dirty connections. Inspect the starter commutator,

and if it is dirty, clean with number

00

sandpaper (do

not use emery cloth or emery paper). Check the

brushes for poor seating

on

the commutator and for

excessive wear.

TESTING

Poor cranking performance can be caused by afaulty

starting motor, defective battery, or high resistance in

the starting circuit.

Check the charge condition of the battery with a

hydrometer.

Ignition

of

explosive battery gases

might cause severe personal injury.

Do

not

smoke while servicing batteries.

Specific gravity should be between

1.290

and

1.225

when

75

percent charged. If not, recharge the battery.

Check electrolyte level. If battery will not recharge,

replace

it.

Keep battery connections tight and clean.

With the starting motor operating, check the voltage

drops (1) from the battery ground terminal post (not

the cable clamp) to the cylinder block,

(2)

from the

cylinder block to the starting motor frame and

(3)

from

the

battery positive post to the battery terminal

stud on the solenoid. Normally, the voltage drops at

(1)

and

(3)

should never exceed

0.6

V

each, even

underthe most severeconditions (extremecold).The

voltage drop at

(2)

should never be permitted to

exceed

0.3

V

under

the

same severe conditions. Tho-

roughly clean all connections

in

any part of the circuit

showing excesively high voltage drops.

If starting motor tests are required, remove the motor

from the engine and test it on a bench. Test the free-

running voltage and current.

TO

START SOLENOID

PSTARTl

NG

L.

I-

I

SOLENOID

/r

GROUND CONNECTION

TO ENGINE

nnnnn

FIGURE

86.

STARTING

SYSTEM

Using a spring scale and torque arm, test the stall

torque, Figure

87.

Multiply the spring scale reading

by the arm length for the torque valve.

If free running speed is low, and starter has a high

current draw with low stall torque, check for tight,

dirty or Worn bushings, bent armature shaft, or loose

field pole screws, allowing armature to drag. Check

also for shorted or grounded armature and field.

A

low free speed with low torque and

low

current

draw indicates an open field winding, high internal

resistance due to poor connections, defective leads,

broken or worn brushes, or scored, worn, or dirty

commutator.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

IQ”d

FIGURE

87.

TESTING

STALL

TORQUE

High free speed with low developed torque and high

current draw indicates shorted fields. Since there is

no easy way to detect shorted field coils, replace and

check for improved performance.

The voltage drop across the solenoid on the starting

motor should be less than

0.3

volts. If not, remove it

for repair.

BATTERY

Engines with aseparatecranking motor normally use

a single 12 volt battery of at least

62

amp-hour

capacity.

The battery charging system maintains the batteries

at or near full charge at all times. Inspect the battery

charging system and adjust the charge rate if batter-

ies appear to be continually discharged.

Adding accessories that draw battery current requires an adjust-

ment

of

the

charge

rate.

If discharge or failure to charge cannot be traced to

the battery charging system, thoroughly inspect and

test the battery, and replace

it

as necessary.

REPAIR

Armature

Inspect the armature for mechanical defects before

checking for grounds or shorted coils.

To

test for grounds, use a 12volt test lamp and check

between each segment of the commutator and the

shaft. Do not touch probes to the commutator brush

surfaces, as this will burn

the

smooth surfaces.

A

growler is necessary to test for shorted coils. With

the armature on the growler, run asteel strip over the

armature surfaces. If a coil

is

shorted, the steel strip

will become magnetized and vibrate. Rotate the

armature slightly and repeat the test. Do this for one

complete revolution of the armature. If the armature

has a short or ground, replace

it.

If the commutator is only dirty or discolored, clean

it

with

00

or

000

sandpaper. Blowsand out

of

rotor after

cleaning. If, however,

it

isscored, rough orworn, turn

it down

in

a lathe.

Field Coils

Using atest lamp and probes, check the field coilsfor

grounding to themotorframe or open circuit. Inspect

all connections to be sure they are properly clinched

and soldered. Inspect the insulation for evidences of

damage.Theonlywayto check forfield coilshorts is

to use the starting motor test.

Bearings

If either the front or rear bearings show excessive

wear, replace them. Drive the old bearings out, and

using an arbor press and the proper arbor, press new

bearings into place.

Brushes

Check the brushes for wear or improper seating.

They should slide freely in their holders. Check the

brush spring tension with a spring scale. To change

spring tension, twist thespring at the holder with long

nosed pliers.

Replace Prestolite brushes when excessively worn,

or when worn to

5/8

inch in length. Replace Mitsubi-

shi, brushes when excessively worn or when worn to

7/16

inch

in

1ength.Some brushesaresoldered to the

field coil. To remove these brushes, unsolderthe lead

and open theloop

in

the field coil lead. lnsertthe new

brush pigtail completely into the loop and clinch

before resoldering.

A

good soldering job is necessary

to ensure good contact and low voltage drop across

the connection.

Over-Running Clutch

Clean the clutch thoroughly but do not dip

in

solvent.

It

cannot be repacked with grease.

It

should slide easily on

the

armature shaft with no

binding. Turn

the

pinion;

it

should rotate smoothly,

but not necessarily freely. Reverse the direction afew

times and

it

should instantly lock and unlock. Replace

the

clutch

if

operation is defective

or

pinion is worn or

damaged.

Shifting Solenoid

See that the plunger moves freely

in

the coil. Check

pull-in coil continuity between the solenoid control

terminal and the solenoid connection to the motor.

Check the hold-in coil continuity between

the

sole-

noid control terminal and ground on the motor.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

SHIFTING

1

\SOLENOID

PLUNGER

SOLENOID

,

FIGURE

88.

STARTING MOTOR

PRESTOLITE STARTER REMOVAL

AND

DlSASSEMBLY

1. Remove connections

to

controls and battery at

shifting solenoid. See Figure

88.

2. Remove nut-holding rear mounting bracket to

engine.

3.

Remove three capscrews holding starting motor

flange to engine and pull out motor.

4.

Remove link pin holding theshift levertosolenoid

plunger and remove shift lever center pin.

5.

Remove through bolts from commutator end of

motor. Pull

off

end cover and lift brushes

off

their

seats.

6.

Pull pinion housing from front end of motor and

lift

armature and clutch out of motor frame.

7.

To

remove over-running clutch from armature,

drive retainer away from lock ring nearfront end

of shaft, remove lock ring and pull assembly off.

Do

not attempt to disassemble cluth assembly.

8.

If necessary to service solenoid, remove four

capscrews and electrical connection holding itto

motor frame. Remove two screws on rear of

sole-

noid to reach switch contacts.

9.

Mount starter motortoengine byadirectreversal

of the removal procedure (Figure

89).

Connect

battery cable and wires to starter.

10. Connect battery cables to battery. Connect

ground last.

FIGURE

89.

STARTING MOTOR FLANGE

PRESTOLITE STARTER ASSEMBLY

Before assembling, soak the bronze bearings in oil.

They are absorbent bearings, designed to hold up to

25

percent of their own weight

in

oil. Be sure the felt

oil pad

is

in

the outer end of the commutator end

bearing.

When the motor is assembled, check the armature

end play.

It

should be between 0.005-inch (0.127 mm)

and 0.030-inch (0.762 mm). Adjust end play by

adding or removing washers on the commutator end

of the armature.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Before installing, check the pinion clearance. Proper

clearance is important

to

ensure starter engagement.

Press on solenoid core to shift

the

pinion into full

mesh and measure the clearance between pinion and

pinion stop, Figure

90.

This should be between

0.07

inch and

0.12

inch

(3.05

mm) (as near

to

0.070

inch

[1.78

mm] as possible). Adjust

the

link screw on the

end

of

the solenoid plunger for proper clearance.

PUSH

PLUNGE

NOT BE REMOVED

FROM

ENGINE

TO

MAKE THIS

~EMENT

(0.07”-0.12”

CLEARAI

SEE

TEXT)

UCE.

FIGURE

90.

PINION CLEARANCE

MlTSUBlSHl STARTER REMOVAL

AND INSTALLATION

1.

Remove both battery cables from battery. Dis-

2.

Disconnect battery cable and electrical lead wires

3.

Remove capscrews and flat washers that attach

4.

Remove starter.

5.

Mount starter motortoengine byadirect reversal

of

the removal procedure. Connect battery cable

and wires to starter.

6.

Connect battery cables to battery. Connect

ground last.

connect ground cable first.

from starter.

starter to mounting bracket.

MlTSUBlSHl

STARTER

DISASSEMBLY

1.

Remove

“M”

terminal nut and wire lead from

solenoid.

2.

Remove the

two

solenoid mounting screws and

remove solenoid.

3. Remove the two through

bolts

and brush holder

retaining screws. Remove rear bracket (Figure

91).

THROUGH

BOLTS

7

REAR BRACKET

W

EM186

FIGURE

91.

REMOVING REAR BRACKET

4.

Remove frame assembly, and brush holder as-

sembly while pulling the brushes upward. Then

remove armature assembly.

5.

Remove cover assembly, (snap ring and washer)

from the pinion shaft (Figure

92).

COVER

d

ES-1195

SNAP

RING

FIGURE

92.

REMOVING SNAP RING AND WASHER

6.

Remove capscrew that secures center bracket to

front bracket. Remove the center bracket; several

washers used to adjust pinion shaft end play can

now be removed (Figure 93).

ADJUSTMENT

~..~

WASHERS

--

CAPSCREW

-

ES-1187

’

FIGURE

93.

REMOVING CENTER BRACKET

71

Redistribution or publication of this document, 

by any means, is strictly prohibited.

7.

Removegear, spring

set

and lever assembly from

front bracket. Note direction

in

which

the

lever

assembly

is

installed.

8.

Push pinion gear and stopper down and remove

retaining ring. Remove stopper, pinion gear,

spring, and pinion shaft assembly.

9.

Inspect

ball

bearings.

If

they are rough

or

noisy

when rotated replace them. The front bearing

is

not replaceable and must

be

replaced with the

bracket.

SOLENOID

TERMINAL

"M'

BEARING

(RETAIN

I

NG

RING)

BRUSH

FHAME HOLDER

ASSEMBLY ASSEMBLY

xw-1255

FIGURE

94.

MlTSUBlSHl

STARTER

oVERRUNNING

-

PINION SHAFT

MlTSUBlSHl STARTER ASSEMBLY

CLUTCH

PIN

GE

For

assembly reverse the disassembly procedure, but

note

the following

items.

See

Figure

94.

Whenever starter motor

is

disassembled apply

grease

to

each

of

the following points. (Recommended

grade: Multemp

PS

No.

2.)

Armature

shaft

gear

Reduction gear

Ball bearing (Both ends

of

armature)

Stopper on pinion

shaft

Sleeve bearing

Sliding portion

of

lever

Pinion gear

'

REDUCTION GE

Pinion

Shaft

End

Play

Adjustment

Adjust end play

so

that

it

is

0.1

to

0.8

mm

(0.0039

to

0.031

5

inch) with the adjusting washers placed

between

center

bracket

and

reduction

gear

(Figure

ES-1191

95).

FIGURE

95.

ADJUSTING PINION

SHAFT

END

PLAY

,

72

Redistribution or publication of this document, 

by any means, is strictly prohibited.

With pinion gear removed, install reduction gear onto

pinion shaft. Place pinion shaft into center bracket

and

secure

with

washer

and

snap

ring.

Measure

the

end play with a feeler gauge between center bracket

and gear.

If

necessary, adjust end play by adding or

FRONT

c

removing adjusting washers.

If

Dinion clear has not been removed, place pinion

PACKING

\

shaft and7eduction gear between front bracket and

center bracket. With lever spring removed and bolt

tightened, push pinion shaft

out

and measure end

play. Adjust end play, if necessary, by adding

or

re-

moving shims.

CENl

BRAC

Pinion Gear installation

Place spring and pinion gear onto pinion shaft. Slide

stop ring onto pinion shaft and install retaining ring

in

groove. Pull stop ring over retaining ring (Figure

96).

\

I

STOP

RING

STOP RING

I

-1

I

SNAP RING

ES-1194

FIGURE

96.

PINION GEAR INSTALLATION

Lever Assembly Installation

Figure

97

shows the correct method of installing the

lever assembly, spring, and packing. Note direction

of lever.

LEVER

LEVER

SPRING

ES-1185

FIGURE

97.

LEVER INSTALLATION

Pinion Gap Adjustment

After assembling starter motor, adjust pinion gap.

1. Remove"M" terminal nut and wire from solenoid.

2.

Connect positive terminal of battery to

"S"

termi-

nal on solenoid and negative terminal to starter

body. With battery connected pinion gear will

shift into the cranking position.

3.

Gently push pinion shaft back towards front

bracket and measure the amount

of

travel (Figure

98).

'

PINION

I

AMCUNT

OF

TRAVEL

I

I

A

(PINION GAP)

-

ES-1192

FIGURE

98.

PINION GAP ADJUSTMENT

4.

The pinion gap should be

0.3

to

2.0

mm

(0.018

to

0.0787 inch). Adjust

by

changing the number

of

fiber washers used on solenoid mounting sur-

face, increasing the number of fiber washers

decreases clearance. Decreasing the number

of

washers increases clearance.

73

Redistribution or publication of this document, 

by any means, is strictly prohibited.

BELT DRIVEN

(35

AMP) BATTERY

CHARGING ALTERNATOR

(Optional)

This information is presented for field useonly. Major

repair should be done in the shop.

Brush

Assembly Removal

Remove brushes as follows:

1.

Remove three screws which fasten voltage regu-

lator to alternator.

2.

Disconnect regulator leads and remove regulator.

3.

Remove two screws on phenolic cover and lift out

4.

Pull brush assembly straight up and lift out.

cover and gasket.

5.

Reverse procedure for assembly (Figure

99).

Brush

Assembly

Tests

Test brush assembly as

follows:

1.

Connect an ohmmeter or test lamp (12 volts) to

the field terminal and

to

the bracket. The test

lamp should not light or resistance reading should

be

high (infinite). If not, there

is

a short and the

assembly must be replaced.

VOLTAGE REGULATOR

MOUNTS HERE

‘8-32

SCREWS

2.

Move one ahrnmeter lead from the bracket to

insulated brush. Use an alligator clip directly on

the brush.

Be

careful not to chip

it.

Resistance

FIGURE

99.

OPTIONAL, BAlTERY

CHARGING,

EXTERNAL ALTERNATOR

reading should be zero (continuity).

3.

Connect ohmmeter leads to the grounded brush

and the brac.ket. Resistance should

be

zero

(continuity).

74

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Engine

Disassembly

4.

As

each internal engine part

is

assembled, coat it

During

first

few

critical moments of operation, the

engine

will

depend on this lubrication.

5.

After

you have internal engine parts reassembled,

the

engine

should turn freely.

If

reasonable care

+

heavily with oil (same grade

used

in

crankcase).

ENGINE REBUILDING

When engine disassembly

is

necessary, remove

complete assemblies (tear down individual compo-

nents like fuel

pump,

breaker mechanism, etc., as

bench

jobs).

Use special

tools

available.

Disassembly

Common sense

will

dictate proper order of

disas-

sem

bly.

As

disassembly progresses, the order may be

changed, as

will

become self-evident.

A

suggested procedure would be as follows:

1.

Radiator, water

pump.

2.

Flywheel-using puller

or

pry-bar method.

3.

Gear Cover-protect oil seal from keyway

4.

Crank Gear-use puller and gear puller

ring.

5.

Loosen accessories such as

fuel

pumps

and oil

6.

Starter motor.

7.

Drain oil-discard

oil

removed.

8.

Cylinder head.

9.

Valves,

springs,

rocker arms.

damage.

filter.

10. Camshaft and gear, rear bearing plate, oil

pump.

11. Piston, connecting rod bearings.

12. Crankshaft.

13.

Try

to

analyze reasons for any parts failure and

necessity

of

the repair.

14.

Cleanliness and neat, orderly work area makes

job

easier to do.

15.

Use

proper meters and gauges. Observe

if

cylinder requires boring, crankshaft needs grind-

ing,

or

if

other major shop work

is

necessary.

Assembly (Use Genuine Onan

Parts)

1.

Engine assembly procedure

is

normally the

reverse of disassembly

-

observing proper

clearances of bearings, connecting rod, proper

fitting

and

sizing

of

piston,

rings,

etc..

2.

Follow proper recommended procedure for fit of

valves, adjusting clearances, and torque

of

all

special items. Use a torque wrench to assure

proper tightness without danger of stripping

threads.

3.

As

each internal engine part

is

assembled, use a

wrench to rotate crankshaft, making certain it

turns freely.

If

tightness

is

noted

after

any opera-

tion,

you

then

know

your

last

step

is

responsible.

and attention have been given, the engine

will

operate efficiently.

6.

At this point, it

is

a matterof mechanically adding

outside accessory items to the block assembly.

Order

of

assembly

is

reverse

of

disassembly.

7.

When engine

is

complete, install controls. Check

the tagged wires. Use wiring diagram to connect

leads to control and leadsfrom control to engine.

All

wires are marked for correct identification.

If

the

unit

is

to work properly,

wires

must

be con-

nected correctly.

8.

The engine

is

now ready for starting. Before final

adjustments,

run

the engine about 15 minutes

under

light load to reach normal operating

temperature.

ASSEMBLY

SUGGESTIONS (Things

to

Keep

in

Mind

During

Engine

Assembly)

1. See Onan Tool Catalog (900-0019)

-

many items

require a special

tool

for correct installation.

Some of these tools are:

Oil

seal

driver

and

guide,

bearing driver.

Valve spring compressor, valve lock replacer,

valve

guide

driver,

and valve seat remover.

Gear

puller

and gear puller

rings.

Piston

ring

spreader and compressor.

Flywheel

puller,

pry bar, armature puller.

Torque wrench, plastigauge (for correct bear-

ing

clearance).

Armature growler, gas pressure gauge (or

manometer).

2.

Wet holes

in

crankcase (holes through crank-

case)

-

always

use

copper (gasket) washers.

3.

Nuts, bolts

and

screws that do not require exact

torque should be tightened

snugly,

then 1/4 extra

turn.

4.

Select proper length

of

any screw or bolt and

position

in

hole. Make

sure

they do not

bottom.

5.

Gasket kits sometimes cover more than one

engine. Therefore, select gasket of correct size

and shape for part being used. Always

use

new

gaskets.

75

Redistribution or publication of this document, 

by any means, is strictly prohibited.

6.

7.

8.

9.

10.

11.

When disassembling engine, mike bearing plate

gasket thickness. Then select proper shim thick-

ness for correct end play.

Shims establish end play. Only one thickness gasket

is

included in kit.

When assembling crankshaft, make sure bearing

thrust washers are in proper position supported

by bearing stop pins. Use cup grease to hold in

place.

When adjusting valve lash, tap rocker arm

so

it is

straight when checking with feeler gauge.

Crank gears are easier

to

remove and install if

heated a slight amount.

Do

not

overheat

or

temper

may

be

lost

and shaft may expand.

See

FUEL

SYSTEM

section for correct engine

timing.

Allow some gear lash, approximately

0.005

inch

(0.13mm) in oil pump.

Donot

installgears tightly

against each other!.

Maintenance

Check the valve clearances at regular intervals (see

OPERATORS

MANUAL).

In addition, clean the com-

bustion chambers and valve seats, as required if

engine loses power or has low compression.

Valve Clearance Adjustments

After engine has reached a stable temperature condi-

tion the valve clearances may be adjusted. It is

recommended that the valve clearance be set with

engine at room temperature (about

75OF

[24O

C]).

Allow at least two hours cooling time after engine

operation.

1.

To

adjust valve clearance on two-cylinder

J

Ser-

ies engine proceed as follows:

A.

Turn flywheel until cylinder which

is

to have

'its valve adjusted is on a compression stroke,

which follows closing

of

intake valve.

B.

Turn flywheel until TC (top center) mark

on

flywheel lines up with timing pointer on gear

cover. Then turn flywheel in

a

clockwise

direction for an additional 10 to 45 degrees.

The timing mark for this position must be

established. In this position, the piston will be

in its Dower stroke with both valves com-

TESTING AND ADJUSTING ENGINES

pletely closed.

C.

Using a feeler gauge, check clearance between

rocker arm and valve, Figure 100. Increase or

reduce clearance until proper gap is estab-

lished; adjust with lock nut which secures

rocker arm to cylinder head, Figure

101.

Refer

to

SPECIFICATIONS

for correct valve clear-

ance setting for your particular engine.

Preparation

Check the following:

1. Put proper oil in crankcase.

2.

Service air cleaner.

3.

Connect fuel line.

4.

Connect load.

5.

Connect fully charged battery.

6.

Check ventilation for proper cooling.

Operation

1.

Start engine

-

(see Diesel Starting Guide).

2.

Check oil pressure.

3.

Run unit 15 minutes to bring

it

up to operating

temperature.

4.

Check for oil leaks, loose electrical connections,

tight fuel lines,and tight exhaust connections.

Adjust valve lash after

50

hours

of

operation following

engine overhaul.

\\

EXHAUST

A67a-2

'

FIGURE

100. CHECKING VALVE CLEARANCES

Adjust

men

ts

Adjust governor for speed and sensitivity.

2.

To

adjust valve clearance on four-cylinder

J

Ser-

ies engine proceed as follows:

A.

Adjust valve clearance

in

firinn order (1-2-4-

3)

sequence. After the coolinfperiod,'adjust

number

1

cylinder according to Steps 1A and

1

B.

After timing the number

1

cylinder, adjust

valve clearance according to Steps

1

C.

IMPORTANT: For complete customer satisfaction, repaint unit

(Onan White, spray can 5259216) and apply insfructions from

Marine Kit.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

.

B.

C.

D.

E.

F.

G.

VALVE

VALVE SEAT

Rev.

FIGURE

101.

SETTING

VALVE

CLEARANCE

To adjust valve clearance for number 2

cylinder, turn flywheel

in

a clockwise direc-

tion 180 degrees (1/2 revolution) from posi-

tion used in Step 2A. The flywheel position

should be between 10 degrees and 45 degrees

past the bottom center (BC).

IMPORTANT:

Four-cylinder engines

do

not have a

BC

mark on the

flywheel.

After timing number 2 cylinder, adjust valve

clearance according to Step 1C.

To adjust valve clearance for the number 4

cylinder, turn flywheel

in

a clockwise direc-

tion 180 degrees (1/2 revolution). The fly-

wheel should be between 10 degrees and 45

degrees past flywheel TC mark.

After timing number 4 cylinder, adjust valve

clearance according

to

Step IC.

To

adjust valve clearance for the number

3

cylinder, turn flywheel

in

a clockwise direc-

tion 180 degrees (1/2 revolution). The fly-

wheel should be between

10

degrees and 45

degrees past BC.

After timing number

3

cylinder, adjust valve

clearance according to Step

1

C.

Testing

The cylinder compression test can be used to deter-

mine the condition of valves, pistons, piston rings,

and cylinders.

To check compression, run the engine until tho-

roughly warm. Stop engine and remove all injection

nozzles. Insert the compression gauge

in

one nozzle

hole. Crank the engine and note the reading. To

check for piston blow-by, squirt a small amount of

SAE

50

oil into the cylinder and repeat the check. An

increase in compression with oil in the cylinder indi-

cates piston blow-by.

Compression of a standard new engine cranking at

about

300

rpm is about 300-350 psi (2070 to 241

5

kPa)

77

prior to Spec P and 350-400 psi (2415 to 2760 kPa)

Spec

P

and later. Compression should be fairly uni-

form; normally with less than 10 psi

(69

kPa) differ-

ence between

the

highest and lowest cylinder, taken

at the same cranking rpm. Excessively high readings

indicate carboned combustion chambers.

Compression readings

will

deviate considerably from

the above readings because of differences in crank-

ing speed, altitude, and ambient temperature condi-

tions. Therefore,

the

specification is given only

as

a

guide. The best indication of leakage is the pressure

difference between cylinders or a compression

increase when oil

is

added to the cylinder.

CYLINDER

HEADS,

VALVES

DISASSEMBLY

Each cast iron cylinder head assembly has alloy

hardened-faced valves, release-type rotators, alloy

hardened inserts, guides, rocker arms, injection noz-

zles, and glow plugs. The push rods run through

shields.

Keep

rockerarms, rocker arm nuts, push

rods,

and tappets in order

so

they

go

back in the same

valve

train position.

1.

Remove rocker box cover, fuel nozzles, and con-

necting oil lines to cylinder heads.

2. Remove intake and exhaust manifold.

3.

Remove capscrews holding each cylinder head

to

cylinder block.

4.

Remove each head. If

it

sticks, rap

it

sharply with

a

soft

hammer. Do not use a pry.

5.

Remove rocker arms and push rods.

6.

Using a valve spring compressor, disassemble

'

the valve assemblies.

Repair

Thoroughly clean all components of the cylinder

head assemblies. Remove all the carbon deposits

from

the

intake and exhaust ports, and clean all

gasket surfaces.

Valves:

Remove all carbon and check each valve for

burning, pitting, or a warped stem. Refinish valves

that are slightly pitted or burned. Use an accurate

valve grinder. Refinish intake valves to a 42 degree

angle and exhaust valves to a45 degree angle. If they

are badly pitted or have a

thin

edge when refacing,

replace them.

Check refinished valves for a tight seal to the valve

seat with an air-pressure-type testing tool or by ap-

plying Prussion Blue to the valve face and rotating

it

against the seat.

Valve

Guides:

Check valve guide to valve clearance.

See the DIMENSIONS AND CLEARANCES section.

If the proper clearances cannot be obtained by

replacing the valves, replace

the

valve guides. Drive

the old valve guides into the valve chambers. Drive

new guides

in

until they protrude

11/32

inch (8.731

mm) from the rocker box side of the head. Ream the

new valve guide to obtain the proper clearance.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Valve

Seafs:

If valve seats are pitted, refinish them.

Using conventional seat-grinding equipment, reface

each seat to a 45 degree angle and a seat width of

0.047

to 0.062 inch

(1.191

to 1.588 mm). You should

be able to reface each seat several times before it

becomes necessary to replace it.

If the valve seats are loose or cannot be refaced,

replace them.

Use Onan tool number420-0272

in

a drill press (Fig-

ure 102) to remove each valve seat. Adjust the tool to

cut 1/64inch (0.397mm)fromtheedgeoftheseat.Oil

the pilot to prevent it from seizing in the valve guide.

Cut each seat down to a narrow rind

on

edges and

bottom and break it out with a sharp tool. Be careful

not to cut into the counterbore bottom.

BE

SURE

TO

FROM

EDGE

OF

FIGURE

102.

REMOVING VALVE SEATS

Thoroughly clean the valve seat counterbore, and

remove any burrs from the edges. If

the

counterbore

is damaged,

it

will have to be machined for an over-

size seat. Oversize seats are available

in

0.002

inch,

0.005

inch, 0.010 inch and 0.025 inch (0.051, 0.127,

0.254, and 0.635 mm). Otherwise, install new stand-

ard size seat inserts.

Drive the new valve seat inserts into place. Be certain

that each seat restssolidly on the bottom of the coun-

terbore at all points.

To

make installation easier, heat

the cylinder head in an oven at 325°F (162OC) for

about 1/2 hour and cool the valve seats

in

dry

ice.

Face each new seat to a 45 degree angle and a width

of approximately 3/64 inch (1.191 mm). The finished

seat face should contact the approximate center of

the valve face. Use Prussion Blue on each valve face

to check this. Make any corrections on the seat, not

the valve face.

When the new seats are installed and faced, insert the

valve into each, and check the clearance from the

valve head to the face

of

the cylinder head.This must

be at least0.025 inch (0.64 mm). If

it

is not, regrind the

seat.

Valve

Springs:

Check the valve springs on an accu-

rate compression scale. Valve spring data is given in

the DIMENSIONS AND CLEARANCES section.

Replace any spring that is weak, cracked or pitted, or

that has ends out-of-square.

VALVE AND HEAD

ASSEMBLY

Use the following procedure on all

J

Series engines

and generator sets, regardless of which valvestem oil

seal

is

used.

Apply SAE

50

engine oil to valve stem oil seals (before installing

valve), valves and valve stems.

1.

2.

3.

4.

5.

Support valve stem seal when installing valves.

Spring retainer should never contact valve stem

seal when valve springs are being compressed to

install spring retainer locks.

IMPORTANT: Units built before June

1962

had

no

valveseals.

Oil stem of each valve lightly and insert each in its

own guide.

Check each valve for a tight seat with an air-

pressure type tester. If a tester is not available,

make pencil marks at intervals on valve face;

observe if marks rub off uniformly when valve is

rotated part of a turn

in

seat. If seat is not tight,

regrind valves.

Using a valve spring compressor, compress each

valve spring and insert valve spring retainer and

retainer locks.

Install head assembly and gasket to cylinder

block. Tighten head bolts to

44

to46 ft.-lb. (60-62

Nm). Follow sequence

in

Figure 103 and Steps A

through C.

n

n

FIGURE

103.

HEAD

BOLT TORQUE SEQUENCE

Use

Never-Seez, Fel-Pro C5-A

or

equivalent thread lubricant

when installing cylinder heat bolts.

A. Tighten cylinder head bolts finger-tight.

B.

Install exhaust manifold and tighten (four

cylinder models only).

Installing manifold now aligns all four exhaust

ports

with

the exhaust manifold heforethe heads are torqued down.

Add exhaust manifold lock tabs to prevent manifold nuts

from coming

loose.

.

78

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C.

Tighten cylinder head bolts in sequence

shown in Figure 103 to

25-30

ft.-lb. (34-41

Nm).

D.

Tighten cylinder head bolts in samesequence

to

44-46

ft.4

b.

(60-62

N

m) .

E.

After

60

seconds, retighten cylinder head

bolts in sequence to 44-46

ft.-lb.

(60-62

Nm).

This step compensates for the compress of

the

cylinder gasket.

Install intake manifold, nozzles, glow plugs, and

oil lines.

Install valve stem cap.

Install push rods, rocker arms, and rocker arm

nuts.

Set valve clearance. See Figure

101.

IMPORTANT: Afler the first

50

hours of operation, retighten

the cylinder head bolts and check valve clearance.

VALVE ROTATOR CLEARANCE

Both the intake and the exhaust valves on all Onan

J

Series engines are equipped with release-type valve

rotators. The cap covering each valve

tip

releases

keeper tension as thevalve is pushed

off

itsseat.This

allows the valve to float

in

its guide. Engine vibration

and cylinder air flow cause the valve to rotate while

floating.

To assure proper operation of thissystem,valvestem

tip-to-cap clearance should be checked every

5000

hours, or whenever the parts are exposed or removed.

Clearance must be maintained at

0.001

to

0.005

inch

(0.025 to 0.127 mm). Too

little

clearance will prevent

valve rotation, increasing the possibility of valve

leakage and engine power

loss.

Too much clearance

can lead to valve breakage.

To

check the clearance, refer to Figure

104

and pro-

ceed as follows:

1. Remove the cap from the valve tip and measure

the depth of the cavity in the cap with a depth

micrometer.

2. Measure thevalve tip height from thecavity depth

to determine the clearance. It should be between

0.001 and

0.005

inch

(0.025

and 0.127 mm).

3.

If the clearance is not within specifications,

replace the cap and keepers as a set. When

replacing the keepers, check for wear on thevalve

spring retainer where it contacts the keepers. If

wear is over 0.003 inch (0.076 mm) replace the

retainer. After replacement of parts, recheck the

clearance. If it is still not within specifications,

replace the valve.

Anytime the valves are to be removed, these mea-

surements should be carried out first. Keep each

valveassembly together as aset.

When

reassembling,

install the keepers with wear in original position.

Keepers can be inverted to use the unworn side, but

the clearance must then be rechecked. Place a drop

of engine oil on the valve stem before replacing the

cap.

VALVE

SPRING

RETAINER

DEPTH

HEIGHT

LP

CLEARANCE

FIGURE

104.

MEASURING VALVE TIP-TO-CAP CLEARANCE

MDJA DECOMPRESSION RELEASE

The decompression release mounts on the cylinder

head with a solenoid on the rocker box cover.

It

holds

the exhaust valve open to allow the engine to build up

speed during starting before compression occurs,

and tostop engine.The mechanism holds the exhaust

valve open when the solenoid is de-energized. If the

release is defective, replace any worn parts; other-

wise, adjust

it,

following the instructions below:

NOTE

Beforeadjusting thedecompression mechanism, thevalves

must be adjusted

for

the

correct

clearance.

Figure 105 shows the decompression release in

detail. The release must operate properly for depen-

dable engine starting and stopping.

1.

With the piston

10

to

45

degrees past TDC on the

power stroke, hold the arm

in

the decompression

position (tension against spring). Turn the set

screw

so

it

just touches the exhaust rocker arm.

The release arm must be tight against the snap

ring during adjustment. Then, turn the screw

exactly one revolution clockwise. The original

factory setting is marked with white or yellow

paint.

79

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by any means, is strictly prohibited.

DECOMPRESS1

ON

RELEASE

ARM

EXHAUST VALVE

LOCK NUT

'

P

I

A705

pw.

DECOM

P

RE

SI

ON

RELEASE ARM

ltJ

RUNNING

POSIT10

OKEN

LINE

INDICATES

OVEMEMWHEN

FIGURE

105.

DECOMPRESSION

RELEASE

NOTE:

If

the

screw

is

lightened

more

than

one

turn,

the

exhaust

vahre

could

hitthe

pistar.

Hold the set screw

and

lock it into position with the

attached nut. Turn the nut finger tight plus

1/4

to

1/2

turn to lock the mechanism.

2.

Release the mechanism to allow compression.

Check the clearance between the screw and

rocker arm. Insert a feeler gauge between valve

and rocker arm to take up valve clearance forthis

check.

If

there is no clearance, back

off

the set

screw until

it

just clears the rocker arm.

When reassembling the rockercover, remove the

solenoid,

dip

the plunger O-ring

in

oil

and rein-

stall when cover

is

on the engine. Align solenoid

so

terminal

SW

is

above terminal

1GN.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

INTERNAL DISASSEMBLY

If

engine disassembly is necessary, observe the fol-

lowing order (Le. Flywheel, Gear Cover...).

As

disas-

sembly progresses, the order may be changed some-

what as will be self-evident. The engine assembly

procedure

is

the reverse of disassembly. Any special

assembly instructions for a particular group are

included

in

the applicable section. When reassem-

bling, check each section for these special assembly

instructions or procedures.

FLYWHEEL

Remove the blower housing.Theflywhee1 isatapered

fit on the crankshaft. Improvise a puller, using at least

a 7/16 inch (11.113 mm) bar, and drill two 7/16 inch

(1 1.1 13 mm) holes2-7/8 inches

(73.025 mm) between

centers. Loosen the flywheel mounting screw a few

turns. Place bar againstthe flywheelscrew and attach

bar, using two 3/8-16 thread screws in the holes pro-

vided in flywheel. Alternately tighten the screws until

flywheel

is

free.

PISTON

DROP

Inches

I

mm

REPLACEMENT

Replacement flywheels are supplied without the tim-

ing markings becauseeach flywheel must befitted to

its engine. The only accurate method of determining

the top dead center (TDC) and port closing

(PC)

points is to measure the piston travel. This is acritical

measurement and should be attempted only with

accurate, reliable equipment.

With the flywheel mounted, remove the head and

install a depth gauge over the front piston. Rotate the

flywheel to find theTDC position on the compression

stroke, and markthis point on theflywheel. Next, turn

the flywheel counterclockwise until the piston drop is

as specified in Table 9. Mark both TDC and piston

drop to PC point on the flywheel.

PORT

BTC

ENGINE CLOSING

TABLE

9.

PISTON DROP DATA

0.102

I

2.59

I

MDJA

I

17degrees

0.128

I

3.25

I

MDJB&MDJC

I

19degrees

(Begin Spec

P)

(Prior

to

Spec

P)

0.155

0.128

0.115

0.128 3.25

MDJF

19 degrees

Ring Gear:

To

remove a damaged ring gear, saw part

way through, then break

it

using a cold chisel and

heavy hammer.

To install a new ring gear, place

it

in an oven heated to

380°

F

-

400OF (192O to 204OC) for

30

to

40

minutes.

Do

not heat ring gear to a bright red

as ring gear may warp and the beat

treatment wiN be destroyed.

When properly heated, ring will fall into place

on

flywheel. If

it

does not go on all theway by itself, drive

it

into

place with

a

hammer.

Do

it

fast and do not

damagethe gear teeth. Ring will contract rapidly and

may shrink to the flywheel before

it

is

in

place. If this

occurs,

a

new

ring gear may be required.

GEAR

COVER

To remove the gear cover, detach the upper governor

ball joint. Remove the governor speed-adjustment

nut and governor spring bracket.

Remove the screws holding the gear cover to the

crankcase. To loosen the gear cover, tap

it

with asoft

hammer.

Governor Shaft

The governor shaft is supported by

two

sets of needle

bearings. To remove the shaft, remove the yoke and

pull the shaft from the gear cover. If the shaft is bind-

ing, clean the bearings. If loose, replacethe bearings.

To remove

the

larger bearing, drive both bearing and

oil seal out from the outside of the gear cover.

Remove thesmaller bearing with an Easy-Out orsim-

ilar tool. Press new bearings and oil seal into place.

See Figure

106.

Gear

Cover

Oil

Seal

Replace the oil seal if damaged or worn. Drive the oil

seal out from inside

the

gear cover. Lay the cover on a

board

so

the seal boss is supported. Using an oil seal

driver, insertthe new seal from

the

inside with rubber

lip toward outside of gear cover (open side of seal

inward) and drive

it

flush with the outside surface.

During gear cover installation, use the driver to pro-

tect the oil seal. See Figure

107.

Assembly, Gear Cover

1.

2.

3.

4.

Work governor shaft to check for binding and see

that the governor shaft end-thrust ball is in place

(Figure 106). Later models have larger ball which

will not fall out.

Turn governor yoke

so

smooth side is toward

governor cup.

Turn governorcupsostop pin

in

gearcoverwill fit

into one of the holes in

the

cup surface (Figure

108). Measure distance from end of stop pin to

mounting face of cover.

It

should be 25/32 inch

(19.844 mm).

If

it

is not, replace

pin.

Pin should be

positioned with open end facing crankshaft seal.

Coat oil seal lip with oil or grease. Set a piece of

shim stock over the crankshaft keyway to protect

seal and install gear cover. Tighten mounting

screws to

15

to

20

ft.-lb.

(20

to 27

Nm).

Before

tightening screws, be sure

the

stop pin is in gov-

ernor hole.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

GOVERNOR ARM

GOVERNOR SHAFT YOKE

(%moth

side

toward

cup)

ROLL

PIN

FITS INTO

HOLE

IN

CUP

BE SURE THAT

OIL

PASSAGES ARE OPEN

GOVERNOR

CUP

8343

GOVERNOR

LL

/2"

FALLEN OUT

FIGURE 106. GEAR COVER ASSEMBLY

GOVERNOR

CUP

INSTALL OIL SEAL

FLUSH WITH THIS

SURFACE

THIS

SURFACE MUST

BE CLEAN BEFORE

INSTALLING SEAL

FIGURE 107.

GEAR

COVER OILSEAL

m

WHEN

GOVERNOR

IS

GOVERkOR CU

GOVERNOR FLY

BAL

Aeo=

El

FIGURE 108. GOVERNOR CUP

To remove the governor cup, remove

the

snap ring

from the camshaft center pin and slide the cup off. Be

sure to catch the ten flyballs that will fall out when the

cup is removed. Figure

108

shows the governor cup.

Repair

Replace any flyballs that have flat spots or grooves.

Replace the cup

if

the race surface is grooved or

rough. The governor cup must be a free spinning fit

on the camshaft center pin, but should be replaced

if

excessively loose or wobbly.

The camshaft center pin extends

out

3/4

inch

(19

mm) from the end of the camshaft. This distance

provides an in-and-out travel distance of

7/32

inch

(5.6 mm) forthe governor cup, as illsutrated. Hold the

cup against the flyballs when measuring. The cam-

shaft center pin cannot be pulled outward or removed

without damage. If the center pin extends out too far,

the cup will not hold the flyballs properly. If

the

dis-

tance is less than

7/32

inch

(5.6

mm), the engine will

race, especially at no load; remove the center pin and

press in a new pin.

Installation

To install the governor assembly, tip the front

of

the

,

unit upward. Set the flyballs in their recesses and

position the governor cup on its shaft. Finally, brush

with heavy grease and install

the

snap ring on the

center

pin.

PISTONS,

RINGS, CONNECTING

RODS

DJ

engines use cam-ground aluminum pistons. Each

piston is tapered and fitted with three compression

rings and an

oil

control ring. Full-floating piston pins

connect the piston to its connecting rod. The pinsare

held

in

place with a snap ring at each end. The lower

end of each connecting rod contains half-shell preci-

sion bearings; the upper end, semi-finished bushings.

Some engines are fitted with

0.005

inch (0.127 mm) oversize pis-

tons at the factory. These engines are marked with an

E

following

the

engineserial number.

Use0.005

inch (0.127 mm) oversize rings

for

these pistons.

82

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Removal and Disassembly

On 2- and 4-cylinder engines, the connecting rod and

cap arestamped for installation in the proper cylinder.

When removing piston assemblies, check the mark-

ing

so

each can be installed in the proper cylinder.

1.

Drain crankcase oil and remove oil base.

2. Remove cylinder heads.

3.

Before pushing pistons out, scrape carbon at top

of cylinder bore.

4.

Remove cap from each connecting rod and push

assembly through top of cylinder bore. Replace

cap and bearing inserts in proper assembly.

5.

Using a ring expander, remove rings from each

piston.

6. Remove two retaining rings and push piston pin

from each piston.

Cylinders

The cylinder walls should be free of scratches, pit-

ting, and scuffing. Check each with an inside reading

micrometer for out-of-round and wear. The bore

measurement should beasspecified and be less than

0.001 inch (0.0254 mm) out-of-round.

If necessary, rebore the cylinder to fit the next availa-

ble oversize piston. Pistons and rings are available in

0.005, 0.010, 0.020, 0.030, and 0.040 inch (0.127,

2.540,0.508,0.762,1.016 mm) oversize. If the cylind-

ers do not need refinishing; remove any existing

ridges from

the

top of the walls with a fine stone.

Pistons

Clean thoroughly and inspect each piston. Clean the

carbon from the ring grooves and be sure all oil holes

are open. If any piston is badly scored or burred,

loose in the cylinder, has badly worn ring grooves or

otherwise is not in good condition, replace

it.

See

Figure

109.

Install pistons with valve relief recess

facing the camshaft side of engine

to match valve positions.

Check the clearances 90 degrees from the axis of the

piston pin and below the oil control ring. Clearance

should be

0.005

to 0.007 inch (0.127 to

0.178

mm).

If

not, replace the piston and check the cylinder for

possible reconditioning.

PISTON PINS

Each piston pin should be a thumb push fit into its

piston at room temperatures. If the pin is excessively

loose, install a new one. If

the condition is not cor-

rected, install the next oversize pin. If

the

piston is

worn enough

so

that the oversize pin will not fit,

replace it.

CAST

IRON

OIL CONTROL

IN

POSITION

-\--

~

INSTALL WITH

VENTS AT BOTTOM

(AWAY

FROM

CLOSED

END

OF

PISTON)

RINGS

PISTON

'

'

VENTS

FIGURE

109.

PISTON

RINGS

RINGS

Inspect each ring carefully for fit in the piston

grooves and for seating on the cylinder wall. Fit each

ring to the cylinder wall at the bottom of its travel,

using a piston to square the ring

in

the bore. Check

thegap with afeeler gauge.

It

should beO.O1O to0.020

inch (0.254 to

0.0508

mm). The practice of filing ring

ends to increase the end gap is not recommended. If

the ring end gap does not meet specifications, check

for the correctness of ring and bore sizes.

A

cylinder

bore that is

0.001

inch

(0.03

mm) under size will

reduce the end gap

0.003

inch

(0.08

mm). If oversize

pistons are used, use the correct oversize rings.

CONNECTING RODS

Clean the connecting rods and check each for de-

fects. Check the connecting rod bushings for proper

clearance with the piston pin. Clearance should be

0.0002 to 0.0007 inch (0.0051 to 0.0178 mm).

If the bushings are excessively worn, press them out

and install one new bushing from each side

of

the

bushing bore. Pressthenew bushingsonly until flush

with the sides of

the

rod to leave 1/16 to 7/64 inch

(1.588 to 2.776 mm) oil groove in the center. See

Figure 110.

CONNECTING ROD BEARINGS

Inspect the connecting rod bearings for burrs, breaks,

pitts and wear. Measure the clearance between bear-

ings and thecrankshaftjournaLThe clearanceshould

be

0.001

to

0.003

inch (0.0254 to 0.076 mm).

If

neces-

sary, replace with new standard or oversize precision

bearings.

83

Redistribution or publication of this document, 

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CONNECTING

ROD

BUSHINGS

BUSHING ENDS MUST

BE FLUSH WITH

SIDES

OF

ROD

TO PERMIT

I/lb”OlL

GROOVE

BETWEEN BUSHINGS

MEASURE CLEARANCE

IN

ABBl

Rev.

FIGURE

110.

CONNECTING

ROD

BUSHINGS

ASSEMBLY AND INSTALLATION

1.

Install connecting rods on each piston with pins

and retaining rings. If new bushings were

in-

stalled, check to see that ends are flush with con-

necting rod to provide for oil recess in center.

2.

Install all rings on each piston. All compression

rings will be marked

top

or identified in some

other manner. Place this mark toward closed end

of piston. Space ring gaps 1/4 of way around

piston from oneanother. Nogapshould be

in

line

with the piston pin.

3.

Position

a

bearing half

in

each connecting rod.

Be

sure there is no dirt under bearing. This could

cause high spots and early bearing failure.

4. Oil cylinder walls. Install each piston

in

proper

cylinder using a suitable installer. Each assembly

should be installed with stamp on piston facing

same direction as when removed.

5.

Position each connecting rod on crankshaft, oil

the journal, and install its rod cap and bearing

half. When installing rod cap, position

so

raised

witness mark on forging matches mark on con-

necting rod. See Figure

111.

6.

Tighten capscrews to specified torque.

7.

Crank engine over by hand to see that all bearings

8.

Install oil base with a new gasket.

9.

Install cylinder heads using proper bolt tighten-

are free.

ing sequence.

10.

Replace oil.

CAMSHAFT

The camshaft is a one-piece machine casting, driven

through gears by the crankshaft.

It

rides on sleeve

bearings pressed into the crankcase.

In

addition to providing a meansof opening and clos-

ing the valves,

the

camshaft operates the injection

pump and fuel transfer pump.

FIGURE

111.

CONNECTING ROD CAP

Removal

1.

Remove rocker arms and push rods from valve

chambers.

2.

Remove injection pump and fuel transfer pump

from engine.

3.

Remove crankshaft gear retaining washer by

removing lock ring on crankshaft.

4.

Lay engine on its side to avoid dropping tappets

and remove camshaft assembly as a group. If

necessary,

pry

it

out using ascrewdriver between

camshaft gear and crankcase.

5.

Remove valve tappets. These can be removed

only from the camshaft end of the push rod holes.

Repair:

If a lobe has become slightly scored, dress

it

smooth with a fine stone. If the camshaft

is

badly

worn or scored, replace

it.

After installing a new cam-

shaft, time the injection pump to the engine. Never

install a new camshaft with old tappets.

Camshaft Gear:

This gear is a pressed fit on the cam-

shaft and drives

it

at 1/2 the crankshaft speed.

To

remove the gear, use a hollow tool or pipe that

will

fit

inside thegear boreand overthe center pin. Press the

camshaft out of the gear bore. Be careful not to dam-

age the center pin.

Camshaft Bearings:

The camshaft bearings should

be replaced if the clearance to thecamshaft is greater

than specified, the bearings show cracks, breaks,

burrs, excessive wear, or other defects.

To

check the

rear bearing, remove the expansion plug at the rear of

the crankcase.

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by any means, is strictly prohibited.

V

PRESS

BEARING

FLUSH

WITH

BOTTOM

OF

RECESS

REAR

EARING

PRESS

BEARING

FLUSH

WITH

FRONT

CRANK-

CASE

SURFACE

ALIGN

OIL

HOLES

FRONT

BEARING

BEARING

FIGURE

112.

CAMSHAFT BEARINGS

NKSHAFT

WASHER

E

FIGURE

113.

CAMSHAFT ENDPLAY

FIGURE

114.

TIMING

MARKS

Press new bearings into place, Figure

112.

Press the

rear bearing flush with the bottom of the expansion

plug recess. Press the front bearing in flush with the

crankcase front surface

so

the oil passages are

aligned.

Do

not attempt to ream the bearings as they

are a precision type. After rear bearing is installed,

insert a new expansion plug

in

the recess, using seal-

ing compound, and expand

it

into place with sharp

blows at its center.

Installation,

Camshaft

Assembly

1. Install key and press camshaft gear on camshaft

until

it

bottoms on flange with no clearance.

2.

Install governor components.

3.

Slide thrust washer ontoshaft. Measure camshaft

end play;

it

should be0.007 to0.039 inch

(0.178

to

0.991

mm). See Figure

113.

4.

Lay engine on its side

or

end and insert push rod

tappets.

5.

Install camshaft assembly

in

engine. Align timing

marks on camshaft gear and crankshaft gear. See

Figure

11.4.

6.

Replace push rods and fuel transfer pump.

7.

When engine is reassembled, install injection

pump following the steps for

Injection

Pump

Installation

in

the

FUEL

SYSTEM

section. This

step is critical.

CRANKSHAFT

The

DJ

Series engines use a counter-balanced duc-

tile iron crankshaft. To increase shaft fatigue durabil-

ity, all crankpin fillets are shot-peened during manu-

facture. The two-cylinder crankshafts ride on two

lead-bronze bearings; the front one is housed

in

the

crankcase, and

the

rear one is in the bearing plate.

The four-cylinder model uses an additional main

bearing with a split-center.

85

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by any means, is strictly prohibited.

CRANKSHAFT

.

-

.

3/16" (4.763

mrn)

TO

BE

SHOT- PEENED

4

ONANNO.

//

420-0275

.

FIGURE

115.

REMOVING

CRANKSHAFT GEAR

Removal

1.

2.

3.

4.

5.

6.

Remove lock ring and retaining washer in front of

crankshaft gear.

Pull off crankshaft gear.

It

has two 1/4-20 UNC

tapped holes for attaching a gear pulling ring.

Use care not to damage teeth if the gear is to be

reused.

See

Figure 115.

Remove oil pan, pistons and connecting rods.

Remove bearing cap from center main bearing.

Remove rear bearing plate from crankcase.

Remove crankshaft through rear opening in

crankcase. Catch upper half of center main bear-

ing support as

it

slides

off

its mounting surface.

inspecfion:

Clean the crankshaft and blow out all oil

passages. Check journals for out-of-round, taper,

grooving or ridges. Pay particular attention to ridges

or grooves on either side of the oil hole areas. Unus-

ual conditions here often point to previous neglect of

oil changes.

If journal dimensions are not within limits, or the

journals are scored, regrind the crankshaft.

Crankshaft Grinding:

Crankshaft grinding requires a

trained, experienced operator working with precision

equipment. Procedures which may besatisfactoryfor

some spark-ignition engines may well be unsatisfac-

tory for diesel applications, resulting

in

expensive

f ai

I

ures.

Special procedures must be observed when rework-

ing diesel crankshafts.

In

addition to machining, the

crankshaft must be shot-peened and super-finished.

Failure to

shot-peen

the crankpin fillets is likely to

cause early failure. When the shaft is machined, fol-

low the directionsand dimensions given in Figure 116

to shot-peen each crankpin fillet.

THIS

AREATO

BE

MASKED

DURING

SHOT-

PEENIN6

OPERATION

I

FIGURE

116.

SHOT-PEENING THE CRANKSHAFT

1. Almen gauge reading 0.012-A

(0.305).

2.

Peen with 0.019 inch (0.482 rnm) .diameter cast

3. Peen for

30

seconds on each crankpin fillet.

4. Mask

off

connecting rod bearing areas.

Undersize bearings and connecting rods are availa-

bleto

reworktheshaftto0.010inch

(0.254rnm),0.020

inch (0.508 rnm), and

0.030

inch

(0.762

mrn) undersize.

steel shot.

Main Bearings:

Replace main bearings if clearances

are greater than limits or if the bearings are worn,

grooved, or broken.

Precision replacement inserts and thrust washers are

available for all main bearings.

Do

not ream the

bearings.

Align the oil holes and press the new bearings into the

front and rear housings. Insert the center bearing

when the crankshaft is reinstalled.

Rear

Oil

Seal;

The rear oil seal is in the rear bearing

plate. If damaged, drive

it

out from the inside of the

plate. Using the oil seal installing tool (Onan

No.

420-0250), install a newsealwith the rubber lip facing

outward (open side of seal inward). See Figure 117.

Drive the new seal flush

with

the rear surface of the

bearing plate. Leave the seal installer on during bear-

ing plate installation to protect the oil seal.

Installation:

After each installation step, check the

crankshaft to be sure

it

is not frozen into place.

1. Press front and rear main bearings into place,

then align bearing and bearing housing oil holes.

Do

not attempt to drivea bearing into a cold block

or

rear bearing plate.

2. Install thrust washers and locking pins.

3.

Oil bearing surfaces and install crankshaft from

rear of crankcase through rear bearing plate hole.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

4. Mount and secure rear bearing plate.

Crankcase

5.

Heat timing gear

on an

electric burner or oven to

about

35OOF

(175°C).

Install

key on crankshaft,

then drivegear into place. Install retaining washer

and lock ring.

6.

Set upper half of center main housing on crank-

shaft and rotate it into place. See Figure 118. Be

sure it is installed with the side marked

front

toward crankshaft gear. Set the two positioning

dowels on the upper bearing mount. Install center

main bearing capand torque bolts to97-102ft.-lb.

(131-138 Nm).

7.

Check crankshaft end play. Use enough rear

bearing plate shims and gaskets to provide

0.010

inch (0.254 mm) to

0.015

inch (0.381 mm) end

play. If gaskets of more than 0.015 inch (0.381)

total thickness are required, use a steel shim of

proper thickness and a thin gasket on each side of

shim. This avoids excessive gasket compression

and maintains bolt torque.

If

the

crankcase requires replacement, a new set of

injection pump shims

will

be furnished with the new

crankcase. These must be used and, in addition,

the

injection pump must be re-timed to the engine. If, on

the four cylinder models, the center main bearing

support requires replacement, the whole crankcase

must be replaced or returned to the factory to have a

new housing fitted.

Break-In Period

Whenever new rings or pistons are installed or the

cylinder refinished, the engine must be run-in before

regular operation can be resumed. Run

the

engine for

15 to

20

minutes at no load, about

30

minutes at 1/3

load, and

2

to 3 hours at 2/3 load. Regular operation

can then be resumed. Avoid light load operation dur-

ing the following several hours for best ring seating

and to prevent oil consumption.

8. Install

.

*-

piston assemblies.

BEARING HALF

PLACE UPPER BEARING

HOUSl

HALF IN POSITION INDICATED

CRANKSHAFT BROKEN LINE. ROTATE INTO

BEARING HALF CENTER

MAIN

BEARING

HOUSING (UPPER HALR

BE

SURE

TO

ALIGN

OIL

HOLES

IN

BEARING AND

HOUSING

ING

BY

FIGURE

118.

CENTER MAIN

BEARING

HOUSING

87

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by any means, is strictly prohibited.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Redistribution or publication of this document, 

by any means, is strictly prohibited.

Onan Corporation

1400 73rd Avenue

N.E.

Minneapolis, MN 55432

612-574-5000 International

Use

Telex: 275477

Fax: 61 2-574-8087

Onan

is

a

registered trademark

of

Onan Corporation

1-800-888-ON AN

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