Onan NH, NHC, NHCV Service Manual

Service

Manual

Engine

940-0751

NHC, NHCV

Spec

E

NH

(RV)

Spec

J-P

4-87

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.

LBWAR”GIThis

symbol

is

used

throughouf

this

manual

to

warn

of

possible serious

personal

injuiy.

1-1

This

sjmbol

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

0

All

local, state and federal codes

should

be consulted

and

0

This

engine

is

not designed or intended for

use

in

aircraft.

complied

with.

Any

such

use

is

at the owner’s sole

risk

General

0

Provide appropriate fire extinguishers and

install

them

in

convenient

locations.

Use

an

extinguisher rated

ABC

by

NFPA.

0

Make sure that

all

fasteners on the engine are secure

and

accurately torqued. Keep guards

in

position over fans,

driving

belts, etc.

0

If

it

is

necessary to make adjustments while the engine

is

running,

use

extreme caution when dose 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.

0

Keep your

hands

away from moving parts.

Batteries

0

Before starting work

on

the

engine, disconnect batteries

to prevent inadvertent starting of the engine.

0

DO

NOTSMOKEwhile 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

0

DO

NOT

fill

fuel

tanks

while engine

is

running.

0

DO

NOT smoke or use an open flame

in

the vicinity

of

the

engine or fuel tank. Internal combustion engine fuels are

highly

flammable.

0

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.

L.

,

0

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:

0

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 complete exhaust system.

If

you

notice achange inthe 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

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 21 2 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.

0

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.

b

5

Table

of Contents

TITLE

PAGE

General Information

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

2

Specifications

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

3

Dimensions and Clearances

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

4

Assembly Torques and Special Tools

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

6

Engine Troubleshooting

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

7

NHC.

NHCV

Installation Guidelines

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

8

Oil System

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

12

Fuel System

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

15

Ignition and Battery Charging

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

28

Starting System

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

34

Engine Disassembly

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

39

Engine Wiring Diagram

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

59

1

General

Information

c

I

NTR 0 D U CTI 0 N

This manual dealswith specific mechanical and electrical 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 for parts identification and for establishing their proper location on assemblies.

The troubleshooting guide is provided as 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-blower 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 competent 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 on the last page of the manual

shows

how the electrical components are inter-

connected.

A

parts catalog (available at the dealer level) contains

detailed exploded views of each assembly and the

individual piece part numbers and 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

as

well as 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 referencetoyourengine.

How to interpret

MOD€L

and

SPEC

NO.

"if'

$ill

f

1

2

34

1.

Factory code for general identification purposes.

2.

Specific Type:

#

S-MANUAL

starting

MS--ELECTRIC

starting

if any.

factory production modifications.

3.

Factory code for designated optional equipment,

4.

Specification (spec letter) which advances with

1

AWARNING

j

INCORRECT SERVICE

OR

REPLACMENT OF PARTS CAN RESULT IN SEVERE PERSONAL INJURY AND/OR EQUIPMENT DAMAGE. SERWCE PERSONNEL MUST BE QUALIFIED

TO

PERFORM ELECTRICAL AND/OR

MECHANICAL SERVICE.

.

2

Specifications

.

This

manual contains

SI

metric equivalents that

follow

immediately

in

parentheses

after the

U.S.

customary

units

of

measure.

~

SERIES

UNIT

OF

SPECIFICATION

MEASURE

NHC

NHCV

Number of Cylinders 2 2 Bore

in 3.56 3.56

Stroke in 3.0 3.0

Displacement

cu in 60

60

Compression Ratio

7.0

to

1

7.0 to

1

Rated Speed (Maximum)

RPM 3600 3600

Power at

BHP 25 22.5

Rated Speed (kW) (18.6) (16.8)

Oil Filter

Full

Flow Full Flow

(mm)

(90.48) (90.48)

(mm) (76) (76)

(cm3)

(983) (983)

Oil

Capacity Without Qt 3.5 3.5

Filter

(litre) (3.3) (3.3)

Filter Change

(I itre) (3.8) (3.8)

(viewed from flywheel)

Clockwise Clockwise

Oil Capacity With Qt 4.0 4.0

Crankshaft Rotation

Governor Variable Speed Mechanical

Valve Clearance (Cold)

Intake in

0.005

(mm)

(0.1 27) (0.1 27)

Exhaust in

0.01 3 0.01 3

(Gasoline Fuel) (mm)

(0.330) (0.330)

Exhaust in

0.01 3

0.01

3

(Lpg and Natural Gas) (mm)

(0.330) (0.330)

Spark Plug Gap in

0.025 0.025

(mm)

(0.64) (0.64)

Breaker Point Gap

-

Static in 0.016 0.01 6

(Full Separation and Engine Cold)

(mm)

(0.41) (0.41)

Ignition Timing

BTC 20° 20°

Cylinder Compression

psi 100 to 120 100 to 120

690

to

827

(kP4

690

to

827

3

Dimensions and Clearances

All

clearances given

at

room temperature

of

7OoF

(21OC) .

All

dimensions in inches (approximate millimetre dimensions in

parentheses) unless

otherwise

specified

.

DESCRIPTION

CYLINDER BLOCK

Cylinder Bore Honed Diameter

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

Maximum Allowable

Taper

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

Out-of-Round

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

Main Bearing Inside Diameter (Without bearing)

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

Main Bearing Inside Diameter (Installed)

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

Camshaft Bearing Bore (Bearing installed)

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

CRANKSHAFT

Main Bearing Journal Diameter

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

Main Bearing Clearance

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

Connecting Rod Journal Diameter

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

Crankshaft End Play

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

CONNECTING

ROD

Large Bore Diameter (Without bearing installed

and rod bolts properly torqued

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

Connecting Rod Side Clearance

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

Piston Pin Bushing Bore (Without bearing)

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

Piston Pin Bushing Bore with Bearing.

(Finished bore)

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

Bearing to Crankshaft Clearance

Nodular iron Rod

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

Aluminum Rod

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

CAMS HAFT

Bearing Journal Diameter

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

Bearing Clearance

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

End Play

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

Camshaft Lift

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

PISTON

Clearance in Cylinder

Measure

90°

to

0.10

inch below oil ring

Strut Type Spec A-C

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

Without Strut Begin Spec

D

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

Piston Pin Bore

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

Ring Groove Width

Top

1

Compression Ring Spec A-C

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

Top 1 Compression Ring Begin Spec D

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

No

.

2

Compression Ring Spec A-C

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

No

.

3

Oil Control Ring

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

No

.

2

Compression Ring Begin Spec

D

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

MINIMUM

Inches

(mm)

3.5625 (90.49)

2.1 87

(55.55)

2.001 5 (50.84)

1.3760 (34.95)

1.9992 (50.78)

0.0025 (0.064)

1.6252 (41.28)

0.005

(0.13)

MAXIMUM

Inches

(mm)

3.5635 (90.51)

0.003 (0.08)

2.1 88 (55.58)

2.0040 (50.90)

1.3770 (34.98)

2.0000 (50.80)

0.0038 (0.097)

1.6260 (41.30)

'

0.009 (0.23)

1.7505 (44.46)

1.751

0

(44.48)

0.0020 (0.051)

0.0160 (0.406)

0.8115 (20.61)

0.8125 (20.64)

0.7504

(1

9.06) 0.7508

(1

9.07)

0.0005

(0.013)

0.0028 (0.071)

0.0020 (0.051)

0.0033 (0.084)

1.3740 (34.90)

1.3745 (34.91)

0.0015 (0.038)

0.0030 (0.076)

0.0120 (0.305)

0.300 (7.62)

0.001

5

(0.038)

0.0035 (0.089)

0.0070 (0.178)

0.0090 (0.229)

0.7502

(19.055)

0.7506 (19.065)

0.0955 (2.426)

0.0965 (2.451)

0.080 (2.032)

0.081 (2.057)

0.0955 (2.426)

0.0965 (2.451)

0.080 (2.032)

0.081 (2.057)

0.1 88 (4.775)

0.1 89 (4.801)

4

DESCRIPTION

MINIMUM

MAXIMUM

Inches

(mm)

Inches

(mm)

Y

.

PISTON PIN

Clearance in Piston

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

Clearance in Connecting Rod

Nodular Iron Rod

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

Aluminum Rod

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

Diameter

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

PISTON RINGS

Clearance

Top Groove

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

Ring End Gap in Cylinder

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

INTAKE VALVE

Stem Diameter

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

Clearance (Stem to Guide)

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

Valve Face Angle

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

INTAKE VALVE SEAT

Seat Cylinder Head Bore Diameter

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

Seat Outside Diameter

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

Valve Seat Width

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

Valve Seat Angle

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

EXHAUST VALVE

Stem Diameter

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

Clearance (Stem to Guide)

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

Valve Face Angle

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

EXHAUST VALVE SEAT

Seat Cylinder Head Bore Diameter

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

Seat Outside Diameter

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

Valve Seat Width

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

Valve Seat Angle

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

VALVE GUIDE

Inside Diameter

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

TAPPET

Body Diameter

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

Bore Diameter

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

Clearance in Bore

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

VALVE SPRINGS INTAKE AND EXHAUST

Valve Spring Length

Valve Spring Free Length (Approx.)

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

Valve Open

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

Spring Load

@

1.375

inch (Valve Closed)

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

Spring Load

@

1.125

inch (Valve Open)

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

Timing Gear.

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

Oil Pump Gear

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

Valve Closed

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

GEAR BACKLASH

0.0001

(0.003)

0.0005

(0.013)

0.00005

(0.001)

0.00055

(0.014)

0.0002

(0.005)

0.0008

(0.020)

.

0.7500

(19.05) 0.7502

(19.06)

0.002

(0.051)

0.008 (0.203)

0.010

(0.254) 0.020

(0.508)

0.3425 (8.70) 0.3430 (8.71)

0.0010

(0.025)

0.0025 (0.064)

44"

1.5645

(39.74) 1.5655

(39.76)

1.5690

(39.85) 1.5700

(39.88)

0.031

(0.787) 0.047

(1.194)

45"

0.341

0

(8.661

)

0.3420

(8.687)

0.0025 (0.064) 440

1.251

0

(31.78) 1.2520 (31.80)

1.2550

(31.88) 1.2560

(31.90)

0.031

(0.787) 0.047 (1.194)

45O

0.344 (8.74) 0.346 (8.79)

0.7475

(1

8.99) 0.7480 (1 9.00)

0.7505

(19.06) 0.7515

(19.09)

0.0015

(0.038)

0.003 (0.076)

1.662 (42.21)

I

.

125 (28.58)

1:375 (34.93)

38Ib

.

(17

kg)

42Ib . (19

kg)

71

Ib

(32

kg)

79

Ib

(36

kg)

0.002

(0.051)

0.003 (0.076)

0.002

(0.051)

0.005

(0.127)

5

Assembly

Torques

The torque values given in Table 1 have been deter-

mined for the specific applications. Standard torque

values must not be used where those listed in Table

1

apply. The engine assembly torques given here will assure proper tightness without danger of stripping threads. All threads must beclean and lubricated with new engine oil before torquing.

Check all studs, nuts, and capscrews, and tighten as required to keep them from working loose. Refer to the

PARTS

MANUAL

for the location of washers and

capscrews.

Y

TABLE

1.

DESCRIPTION

Cylinder Head Nuts (Cold)

Asbestos Gasket without Asbestos Gasket with Graphoil Gasket without Graphoil Gasket with

Compression Washers..

..

Compression Washers..

..

Compression Washers..

..

Compression Washers..

..

TORQUE

.

SPECIFICATION DESCRIPTION

Ft.-Lb.

Nm

Rear Bearing Plate..

.........

Connecting Rod Bolt

18-20 (24-27) Iron Rod

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

Aluminum Rod

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

13-1 5 (1 8-20) Flywheel Capscrew

..........

Starter Mounting Bracket to

14-1

6

(1 9-22) Oil Base Screws

...........

Gear Case Cover

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

11-13 (15-18) Oil Pump..

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

Other 3/8 Cylinder Block

Nuts

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

Intake Manifold

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

Exhaust Manifold

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

TORQUE

SPECIFICATION

Ft.-Lb.

Nm

25-28 (34-38) 27-29 (37-39)

14-1

6

(1 9-22)

50-55

(68-75)

25-35 (34-47)

8-10 (11-14) 7-9 (10-12)

18-23 (24-31

)

20-23 (27-31) 20-23 (27-31

)

Special

Tools

The following special tools are available from Onan.

For further information see

TOOL

CATALOG

900-0079.

Valve

Seat Driver Valve Guide Driver Oil Guide and Driver Combination Bearing Remover

(Main

and Cam)

Combination Bearing Driver (Main and Cam)

Flywheel

Puller

6

Engine

Troubleshooting

.

7

NHC,

NHCV

Installation Guidelines

VENTILATION

The engine must be provided with a supply of fresh air for cooling and for combustion (Figure

1).

Pressure Cooled Engine

Position the air inlet opening directly in front of the engine and as close to the engine blower wheel as

possible.Theareaoftheinletshould

be not lessthan

80

square inches

(516

cm'). If louvers or grill work are used, increase thearea to compensate forthe reduced air flow. Provide extra ventilation if the driven load generates heat during operation.

The heated air outlet must allow the heated air to escape freely and prevent recirculation with thecool-

ing air. A duct between the compartment air inlet and

theengine blower housing may be necessary. Locate the air outlet opposite the intake or at least at a

90

degree angle. The area of the outlet should be at least

15

percent larger than that of the inlet. Allow suffi-

cient room on all sides to permit access forservicing.

Open Air Installation

For installations where the engine is operated out-

side, ventilation will be no problem. However, in pro-

tecting theengine from theelements, seethat nothing

obstructs the flow of air around the engine.

Vacu-Flo

Cooled Engine

The vacu-flo equipped engine uses an integral flywheel-centrifugal fan to pull cool air into the engine shroud and over the cooling finsand surfaces of the engine (Figure

1).

The heated air is directed through an airtight scroll which encasestheflywheel fan. The scroll may be positioned to discharge heated

air in the downward orthe upward left or upward right direction. This is possible because the back section of the scroll (Figure2) has four identical holes shaped to fit over the end of the starter motor. The scroll outlet has a mesh-type screen for safety.

.

The ouflef

of

the vacu-flo scroll

@!@%I

musf nof be resfricfed or overheafing will result. Engine overhea fing can cause troubles ranging

from

vapor lock

to

scored pistons and

cylinders.

The area of the air inlet must be at least

300

square

inches

(19.35

m2).

If

a filter, grille, or louver

is

used, the inlet opening must be increased accordingly. The air outlet opening should be located as close to the engine

as

possible.

PRESSURE COOLED

m

PRESSURE COOLED

m

VACU-FLO

COOLED

FIGURE

1.

AIRFLOW

THROUGH ENGINES

Iftheduct length exceeds5feet

(1524

mm), increase

duct size

30

percent. Use no more than two

90

degree

radius-type (not square-type) elbows if

it

is necessary to change air flow direction. When aduct is used between the scroll discharge and

the

outlet vent, its unobstructed airflow area must be at least as large as the scroll discharge. The cross-sectional area of the duct must be increased if air flow is restricted by ends, long runs, screens, or the exhaust pipe.

b

8

The safety screen used to cover

1

vents must be IN-inch

(6.35

mm)

mesh,

or

larger,

to

permit sufficient air flow and must

be commensurate

with

safefy standards for hazard-

ous

moving parts to avoid personal contact. Provide a short canvas section between the engine air outlet and the external duct or opening to absorb vibration. If operation

in

cold weatheris likely, installing a shut-

ter

in

the air outlet is advisable. Cold weather can

cause overcooling if air flow is

not

regulafed.

SCROLL

BACKPLATE

mi@

FIGURE

2.

VACU-FLO

SCROLL

POSITIONS

EXHAUST

Usea length

offlexiblestainlesssteel

tubing between the engine exhaust outlet and any rigid piping to absorb engine vibration. Shield the

line

if

it

passes

through a combustible wall or partition. If turns are

necessary, use sweeping type (long radius) elbows.

Increase one pipe size (from manifold outlet size) for each additional ten feet in length. Locate the outlet away from the air intake.

CARBURETOR

AIR

INTAKE

Proper engine efficiency depends upon a supply of fresh air to the carburetor. Under special conditions, it may be necessary to move the air cleaner off the engine, using a longer connection hoseas necessary. For extremely dusty or dirty conditions, install a special heavy duty air cleaner.

MOUNTING

There are several acceptable methods of mounting the engine. Among factors to be considered are: location, method of coupling the engine to the load, type of foundation or support, etc. The engine should be mounted on a level surface if possible. Maximum operation angle is

15

degrees sideways,

30

degrees frontto reartilt. Iftheengineistooperateatanangle, be sure to re-mark the oil level indicator to compensate for the tilt.

The type of installation can affect the life of the engine, the cost of operation, and the frequency of necessary service. Plan the installation carefully to ensure the best performance.

Because

of

the great variety of uses and the many variations of the engine, these installation instructions are typical

or

general in nature. Use the installation

recommendation given as a general guide.

EXHAUST

SYSTEM

Make regular visual and audible inspections of the

exhaust system throughout the entire life of the

engine. Locate leaks in muffler and piping while the engine is operating. Repair all leaks immediately after they are detected for personnel safety.

Should a vacu-flo engine chronically overheat, the most likely sources of the problem are:

1,

Air inlet is obstructed or too small to allow proper

2.

Air discharge opening is partially blocked by

3.

Recirculation of heated air into fresh air inlet.

Inhalation

of

exhaust

gases

can

7)

result in serious persona/ jnjuv

or

death. Inspect exhaust system audibly and visually for leaks daily. Repair any leaks immediately.

ventilation. external ducts or exhaust systems.

9

CONNECTING

THE

LOAD

The dimensions of various power takeoff shafts are as follows:

~~

SHAFT

STD

DIAMETER LENGTH

KEY SIZE

1-711 6 3-1/16 318

(36.51

mml

(77.78

mml

(9.5

mm)

Rockford

Clutch

Gear

Reduction

Belt Drive

V-belts are preferable to flat belts. Consult a reliable

belting supplier for recommendations regarding size

of pulleys, number

of

belts, etc. required. A typical

belt drive installation

is

shown in Figure

3.

1-7/16 3-1/16 318

(36.51

mm)

(77.78

mm)

(9.5

mm)

1-114 2-314

1

I4

(31.75

mm)

(69.85

mm)

(6.35

mm)

~KEEPSHAFTS

OFENGINE

I

?AND LOAD PARALLEL?

I

.

..

---

_-

BELT

IN

-PULLING LOAD

FIGURE

3.

DRIVE BELT INSTALLATION

Comply with the following installation requirements:

1.

2.

3.

4.

5.

The shafts of the engine and the load must be

parallel with each other.

The pulleys

of

the engine and the load must be in

alignment. Mount the engine pulleys as close

to

the engine

as possible. If the installation permits, belts should run

horizontally.

Some method of disconnecting the load forstart-

ing is recommended. If a clutch

is

not used, a

belt-tightener idler arrangment can be used.

Flexible Coupling

If aflexiblecoupling engine-to-load drive is used, the load shaft must be in line and centered with the

engine shaft (Figure

4).

Reduction Gear

Drive

Reduction gear drives are mounted at the factory

(when ordered). The method of connecting the load

is

thesameaswhen connecting directlyto theengine

shaft.

I

wf

SHAFT-

LOAD

\

FIGURE

4.

FLEXIBLE COUPLING

Drain the gear box after the first

100

hours of opera-

tion and refill with fresh lubricant of the recom-

mended grade. Repeat this procedure every six months thereafter, or every

100

hours.

Use only

SAE

50

motor oil or

SAE

90

mineral gear oil. Do not use lubricants commonly known as extreme pressure lubricants, hypoid lubricants, etc.

Maintain the proper oil level between changes. Overfilling will cause foaming, which can lead to an

oil

leak due to overheating. Remove the filler plug on top of the case and the oil level plug from the face of the gearcase. Fill thecaseuntiltheoil just beginstoflow from the oil level plug hole. Gear box holds

1/2

pint

U.S.

measure

(.24

litre). Reinstall both plugs.

Clutch Installation

A

Rockford Clutch can be installed atthe factory or in

the field, installation procedures are provided with

the clutch.

(FASTEN

UNDER

CONVENIENT

BOLT

ON

ENGINE)

FIGURE

5.

BATTERY CONNECTIONS

,

10

.

BATTERY CONNECTIONS

(Engines

with

Automotive Type Separate Starter)

Verify

battery

polarity

before connecting battery

cables. Connect negative cable last. Connect the

12

volt battery positive cable to the

engine start switch terminal. Connect

the

battery negative cable to the ground point on the engine oil base (Figure

5).

OUT-OF-SERVICE PROTECTION

Protect an engine that will be out-of-service for more than

30

days as follows:

1.

2.

3.

4.

5.

6.

Run the engine until

it

reaches normal operating

tern peratu re. Turn off the fuel supply and run the engine until

it

stops. Drain oil from

oil

base while the engine is still warm. Refill with fresh crankcase oil and attach a tag stating viscosity used.

Remove spark plugs. Pour

1

ounce

(2

table-

spoons or

28

grams) of rust inhibitor.or

SAE

#50

oil intothecylinders. Cranktheengineoverafew times. Reinstall spark plugs.

Service air cleaner as outlined in

MAlNTENANCE

section. Clean governor linkage and protect by wrapping

with

a

clean cloth.

7.

Plug exhaust outlet

to

prevent entrance of

mois-

8.

Wipe entire unit. Coat rustable parts with a light

9.

Provide a suitable cover for the entire unit.

ture,

dirt,

bugs, etc.

film

of

grease

or

oil.

10.

If battery equipped, disconnect and follow standard battery storage procedure.

1.

2.

3.

4.

5.

6.

7.

IAWARNING

I

RETURNING UNIT TO

SERVICE

Remove cover and all protective wrapping. Remove plug from exhaust outlet.

Check tag on oil base and verify that oil viscosity is still correct for existing ambient temperatures.

Clean and check battery. Measure specific grav-

ity

(1.260

at

77'

F

[25O

C])

and verify level to be at split ring. If specific gravity is low, charge until correct value is obtained. If the IeveLis low, add distilled water and charge until specific gravity is correct.

Check that fuel filter and fuel lines are secure, with no leaks.

Check carburetor; adjust if necessary. Connect battery. Start engine in

a

well ventilated area. Exhaust smoke when engine is started is normal and is usually caused by the rust inhibitor oil.

EXHAUST

GAS

IS

DEADLY!

Exhaust gases confain carbon monoxide, a poisonous gas that can cause

unconsciousness and death. It

is

an odorless and colorless gas formed during

combusfion of hydrocarbon fuels. Symptoms of carbon monoxide poisoning

are:

Dizziness Vomiting Headache Muscular Twifching

Weakness and Sleepiness Throbbing in Temples

If you experience any of these sympfoms, get out into fresh air immediately, shut down the unif and do not use until

if

has been inspected.

The best protection against carbon monoxide inhalafion

is

proper installation and regular, frequent inspections of the complefe exhaust system. If you nofice a change

in

the sound or appearance of exhaust system, shut the unif down

immediately and have

if

inspected and repaired at once by a competent

mechanic.

Oil

System

CRANKCASE OIL

Refer to engine nameplate or

Periodic Maintenance

Schedule,

located in the Operator's Manual, for oil change interval. If operating in extremely dusty, high ambient, or low ambient conditions change oil more often.

Run engine until thoroughly warm before draining oil. Stop the engine, place a pan under the drain outlet and remove the oil drain plug or open the drain valve. After the oil is completely drained, replace the drain plug

or

close the drain valve. Refill with oil of the correct

API

classification and appropriate

SAE

viscosity grade for

the temperature conditions.

Oil

must meet or exceed the API designation

SF

or

SF/CC.

Refer to the chart for correct

oil

viscosity grade.

Crankcase pressure can blow out

hof

oil and cause serious burns.

Do

NOT

check oil while the engine

is

operafing.

Hot crankcase oil can cause burns if

laWAR"Gl

it is spilled or splashed on skin. Keep iingers and hands clear when removing the oil drain plug and wear protective clothing.

ALWAYS REPLACE

TIGHTLY

OR

OIL

LEAKAGE MAY OCCUR

FULL CAUTION-DO NOT OVERFILL

ADD ONE QUART

(0.95

litre)

c-1000

FIGURE

6.

CRANKCASE OIL FILL

-1

Do

not overfillcrankcase. Excess oil

causes higher operating fempera-

tures and may cause foaming.

Oil level should beto the

FULLmarkofthedipstick.Start

engine and run for a short time to check for oil leaks around the drain plug.

I

60

80

100

0

20

40

0

io

20

30

40

-20

-10

ERATURE RANGE

YOU

EXPECT

BEFORE

CHANGE

FILTER

7.

OILFILTER

OIL FILTER CHANGE

.

Refer to engine nameplate or

Periodic Maintenance

Schedule,

located in the Operator's Manual, for oil filter change interval. If operating in extremely dusty, high ambient,

or

low ambient conditions change oil more

often. Spin

off

oil filter element and discard it. Thoroughly clean filter mounting surface and install new element, making sure new gasket is inserted in the element.

b

12

.

Apply a thin film of oil to the gasket. Spin element down by hand until gasket just touches mounting pad and then turn down an additonalV4-1/2 turn.

Do

not

overtighten.

To

disassemble, remove breather hose from

cap

and valve assembly. Remove cap and valve assembly and wash in a suitable solvent. Replace cap and valve if

balls do not move freely.

Pull

baffle out and wash

in

solvent.

To

allow free operation of the valve, screens

must be positioned as shown in Figure

8.

With oil in crankcase, start engine and check for leaks around filter element. Retighten only as much as necessary to eliminate leaks; do not overtighten.

CRANKCASE BREATHER

The crankcase breather prevents pressure from

building up in the crankcase.

It

also prevents oil contamination by removing moisture or gasoline vapors and other harmful blow-by materials from the crankcase. Thesevapors are routed to the carburetor where they are mixed with incoming air and burned in

the combustion chamber. Asticky breathervalve can

cause leaks, high oil consumption, rough idle, reduced engine power and a rapid formation of

sludge and varnish within the engine.

Crankcase Breather Service

This engine uses a crankcase breather valve for maintaining crankcase vacuum. If the crankcase becomes pressurized as evidenced by oil leaks at the seals, clean baffle and valve in a suitable solvent.

Clean or replace crankcase breather baff le periodically.

Besure baffle material doesn’t come apartand workinto

the manifold.

CAP

AND

VALVE

HOSE

CLAMP

PRESSURE LUBRICATION

All engines usean oil pumpto provideaconstantflow of oil to theengine parts.TheoiI supply collects in the oil base where

it

is picked up by the oil pump pick-up

cup. A by-pass valve is used

to

control oil pressure.

Drain oil before removing oil base and always use a

new gasket when replacing the oil base.

Oil

Pump

The oil pump (Figure

9)

is mounted behind the gear

cover and

is

driven by the crankshaft gear. Inlet pipe and screen assembly are attached directly to the pump body. A discharge passage in pump cover registers with a drilled passage in the crankcase. Parallel passages distribute oil to the front main bearing, rear main bearing, and pressure control bypass valve.

OIL

PUMP

PICK-UP

CUP

OIL

PUMP

ASSEMBLY

CRANKCASETURNED

ON

LEFT

SIDE

FIGURE

8.

CRANKCASE BREATHER

FIGURE

9.

OIL

PUMP

ASSEMBLY

13

Circumferential grooves in the main bearings supply oil to connecting rod bearings through drilled passages from each main journal.

A

drilled passage

connects the front main bearing oil supply to the front camshaft bearing; rear cam bearing is splash lubricated. Oil overflow from the bypass valve provides

lubrication to the camshaft drive gears. Normal oil pressure should be

30

psi

(207

kPa) or

higher when the engine is at normal operating temper-

ature. If pressure drops below this value at governed speed, inspect oil system for faulty components.

Check oil pump thoroughly for worn parts. Prime the oil pump with lubeoil before reinstalling. Except for gaskets and pick-up cup, component parts

of

the pump are not

available individually. Install a new pump assembly

if

any parts are worn.

.

Oil

By-Pass

Valve

The by-pass valve (located to the right and behind gearcover, Figure

10)

controls oil pressure byallowing excess oil to flow directly back to the crankcase. Normally the valve begins to open about

20

psi

(1

38 kPa).

HEX

CAP

SCREW

FLAT

WASHER

SPRING

VALVE

The valve is non-adjustable and normally does not

need maintenance. Determine if valve is operating normally by inspecting plunger action as follows:

1.

Remove the 3/8

x

24

x

7/8

cap screw located

behind gear cover and under governor arm.

2.

Remove spring and plunger with a magnet tool.

.

3. Determine proper valve operation by checking thespring and plunger according to the following measurements.

.

Plunger Diameter..

. . . . . . . .

0.3105 to 0.3125 in.

(7.89

to

7.94

mm)

Spring

Free Length..

.

. .

. . .

1.00

inch

(25.4

mm)

Load

.

..

. . .. . .

. . .

2.620.2

Ibs.

(11.6kO.9

N)

when compressed to

0.5

inch

(12.7

mm)

4.

Check the valve seat and clean away any accu-

mulation of metal particles which could cause erratic valve action. Verify that the valve seat is not damaged.

5.

Clean plungerand spring in partscleaning solvent

and install.

FIGURE

10.

BY-PASS VALVE

14

Fuel

System

Carburetor

Sidedraft LUA

Nikki

CARBURETOR ADJUSTMENTS

The carburetor mixture screws and the float level were set for maximum efficiencyat thefactoryand willseldom require readjustment.

If

adjustment seems necessary, first be sure the ignition system is working properly and is not the source of the problem.

~

Idle Mixture

Main

Mixture

1

to

1-112

1-318

to

1-518

1

to

1-1/2

1-1

/4

to

1-1

/2

1-1

/2

NA

If

adjustment

is

needed, refer to Figures

11

and

12

and

Table 1 and proceed as follows:

TABLE

1.

CARBURETOR ADJUSTMENTS

1.

Turn mixture screw(s) in until lightly seated, then back them out the number of turns specified in Table

1.

-1

f

oosen packing nut before turn-

ing main fuel adjustmenf and

tighfen

to

a snug

fit

after adjustment has been

made. Hold

the

adjustment while tighteningpacking

nut.

Failure

to

tigbfen

the

packing nut can

result

in

leaking fuel, creafing

a

serious fire hazard.

ACAUT~ON

Forcing the mixture adjusfment

I

screws

tight

wi//

damage the needle and seat. Turn in only untillight tension can be felt.

IDLE

ADJUSTMENT

SIDEDRAFT

CARBURETOR

2. Start the engine and allow it to warm up thoroughly (at least

10

minutes).

3.

Move the engine speed control to the slow position.

4.

Determine if the engine has a governor low speed

adjustment screw (Figure 12).

5.

Pull the governor back (Figure 12)

so

the throttle stop screw is against its stop. Continue to hold the governor arm in this position while completing the adjustments described in steps 6 through

8.

6.

If the governor does not have a low speed adjustment screw, adjust the throttle stop screw to obtain

1200

rpm.

If

the governor does have a low speed adjustment screw, adjust the throttle stop screw to obtain 1100 rpm.

7A.

Sidedraft and

LUA

carburetors:

Turn the idle adjustment screw in until engine speed drops and then out until engine speed drops again. Over a narrow range between these

two

settings, engine speed will be at its maximum. Setthe idle adjustment screw about

1/8

turn outward from the midpoint of this

range.

B.

Nikki

carburetor:

This carburetor has a limited

adjustment range between the stops of

k

1

/8

turn.

Adjust carburetor for highest rpm within this range.

8.

Re-adjust the throttle stop screw to obtain the rpm

specified in step

6

and release the governor arm.

LUA

CARBURETORS

LIMITER

CAP-

FS-1406-2

NlKKl

CARBURETORS

FIGURE

11.

MIXTURE

ADJUSTMENTS

15

9.

10.

Engines without a governor low speed adjustment screw require no further

low

speed adjustments. Engines with a governor low speed adjustment screw require the following low speed adjustment:

A.

Check to see that the governor linkage moves freely and is not binding.

B.

Adjust the governor low speed adjustment screw to obtain

1200

rpm.

Check the main mixture adjustment (sidedraft and LUA carburetors only) by rapidly accelerating the engine from idle to full speed. The engine should accelerate evenly and without hesitation. If it does not, turn the main adjustment screw out in

1

/8

turn increments until the engine accelerates smoothly, but do not turn it out more than

1

/2

turn beyond the

original setting.

THRCI~I~STOP~

CARBURETOR

Cii

I\

GOVERNOR

CONTROL

LINKAGE

GOVERNOR

SPRING

GOVERNOR

GOVERNOR LO

SPEED ADJUSTMENT

[g!$$gvz

STOP SCREW

SCREW

FIGURE

12.

IDLE SPEED ADJUSTMENT

Float

Adjustment

An exceedingly high float setting will usually result in an engine that is hard to start when warm. If the setting is too low, the engine may not receive enough fuel under sudden acceleration or load change. Adjust setting as follows:

1.

Disconnect throttle control, choke leads, breather hose, air cleaner inlet hose, and fuel line from carburetor.

2.

Remove the four bolts that hold the intake manifold assembly in place and remove the complete carburetor and intake manifold assembly as one

unit Then remove carburetor from intake manifold for easier handling when checking float level.

3.

Separate the upper body of the carburetor from the fuel bowl section.

4.

Measure float level (Figure

13).

5.

If the setting is incorrect, remove the float assembly to adjust. Bend the assembly slightly at the location specified in Figure

13.

71

Attempting adjustments

wifh

ACAUT'oN

the float assembly installed may

result in deformation of the inlet needle and seat.

NEEDLE BEND FLOAT

AND

SEAT

TANG HERE

BEND TAB

1/8f1/16

INCH

BOWL

~LANGE

GASKET

A91

3rw.

SIDE DRAFT CARBURETORS

U

FLOAT LEVEL ADJUSTMENT

WITH

FUEL

NlKKl

carburetor

with

limited

idle mixture

adiustment

BEND FLOAT

STRAIGHT TAB HERE WALBRO

Ffg::f

BEND FLOAT ARM

I

HERE TOADJUST

MINIMUM BEND FLOAT ARM

FLOAT DROP HERE

TO

ADJUST

NO FUEL

FS-1683

FUEL LEVEL

0.25

INCH

NO FUEL

FLOAT LEVEL ADJUSTMENT LUA CARBURETORS

FIGURE

13.

FLOAT

LEVEL

ADJUSTMENT

FLOAT DROP ADJUSTMENTS

4

FS1524

16

"

CARBURETOR OVERHAUL

Carburetion problems that are not corrected by mixture or float adjustments are usually a result

of

gummed-up fuel passages or worn internal parts. The most effective solution is a carburetor overhaul.

In general, overhauling a carburetor consists of disassembly, a thorough cleaning, and replacement of worn parts. Carburetor repair kits are available that supply new gaskets and replacements for those parts most subject to wear.

General instructions for overhauling a carburetor are given below. Carefully note the position of all parts while removing to assure correct placement when reassembling. Read through all the instructions before beginning

for a better understanding of the procedures involved. Carburetor components are shown in Figures

14,

15

and

16.

Ignition

of

fuel can cause serious

laWAR"Gl

personal injury

or

death

6y

fire or

explosion.

Do

not permit any flame, cigarefte,

or

other

igniter near the fuel system.

Removal and Disassembly (Except Nikki)

1.

2.

3.

4.

5.

6.

7.

Disconnect all lines, linkages, wires, and attaching nuts or bolts; then remove the carburetor from the engine. (Downdraft carburetors may require removal of the intake manifold to disconnect.)

Remove air cleaner adapter, if

so

equipped, and

automatic choking assembly. Remove throttle and choke plate retaining screws,

then plates. Pull out throttle and chokeshafts, being careful not to damage the teflon coating applied to some throttle shafts.

Remove main and idle mixture screw assemblies. On downdraftcarburetors, remove attaching screws

and separate upper and lower carburetor sections. On sidedraft models, unscrew the retaining screw and remove fuel bowl from the upper carburetor body.

Carefully note position of float assembly parts then slideout retaining pin and remove the float assembly, any springs or clips, and the needle valve.

Unscrew and remove needle valve seat.

Removal and Disassembly (Nikki)

1.

Remove air cleaner and hose.

2.

Disconnect governor and throttle linkage, choke

control and fuel line from carburetor.

3.

Remove the four intake manifold capscrews and lift complete manifold assembly from engine. Remove carburetor from intake manifold.

4.

Remove main jet and idle adjustment needle.

5.

Remove attaching screws and separate upper and

lower carburetor sections.

6.

Carefully note position of float assembly parts, then

7.

Remove needle valve.

pull out retaining pin and float assembly.

Cleaning and Repair

1.

Soak all metal components not replaced in carburetor cleaner. Do not soak non-metal floats or other non-metal parts. Follow the cleaning manufacturer's recommendations.

2.

Clean all carbon from the carburetor bore, especially where the throttle and choke plates seat. Be careful not to plug the idle or main fuel ports.

3.

Dry out all passages with low pressure air

(35

PSI).

Avoid using wire or other objectsfor cleaning which

may increase the size of critical passages.

4.

Check the condition of the adjustment needle; replace if damaged. Replace float if loaded with fuel

or damaged.

5.

Check the choke and throttle shafts for excessive play in their bore. This condition may necessitate replacement of the carburetor.

6.

Replace old components with new parts.

Reassembly and Installation (Except Nikki)

1.

Install needle valve and seat, fuel bowl gasket, and

float assembly. Make sure that all clips and springs are properly placed and that the float moves freely without binding. Check float level and adjust as

necessary.

2.

Rejoin upper and lower carburetor sections on

downdraft carburetors

-

fuel bowl and upper

carburetor body on sidedraft models. The float spring on Zenith sidedraft carburetors

rides on the inner face of the fuel bowl. Be sure to catch the end of the spring when reinstalling the

bowl (Figure

15).

3.

Slide in throttle shaft and install throttle plate, using

new screws if furnished

in

repair kit Before tightening the screws, the plate must be centered in the bore.

To

do

so,

back

off

the throttle stop screw as necessary and completely close the throttle lever. Seat the plate by tapping with small screwdriver, then tighten screws. Install the choke shaft and plate in the same manner.

4.

install main and idle mixture screw assemblies. Turn in screws until lightly seated and then out the number of turns specified in Table

1.

ACAUT~ON

Forcing the mixture adjusfmenf screws tigbt will damage the

needle andseat. Turn

in

only

unfilligbt tension can

be felt.

5.

Reinstall carburetor on engine and connect fuel lines, linkages, and wires.

6.

Reset mixture screws according to directions given earlier in this section. Install air cleaner adapter, where used, and air cleaner.

17

Reassembly and Installation

(Nikki)

t

CHOKE PLATE

1.

2.

3.

4.

5.

6.

7.

Install needle valve, main jet, and float assembly. Make sure float pivot pin is properly placed and float moves freely without binding.

Turn carburetor on its side and measure float level (Figure

13).

Adjust float level only if necessary.

Measure float drop (the distance from the top of

carburetor body to top of float). Adjust only if

necessary. Position gasket on lower carburetor section and

install upper carburetor section. Install idle adjustment screw, throttle stop screw,

and fixed main jet plug.

Mount carburetor on intake manifold and install

assembly on engine.

Mount air cleaner assembly. Connect air intake hose, breather hose, fuel line, vacuum line, and

throttle linkage. Adjust carburetor and governor according to dir-

ections given in this section.

IDLE ADJUSTMENT

NEEDLE

\

P)

CHOKE

PLATE

!----?

!O

THROllLE SHAFT

FLOAT SPRING AND LEVER

gj

;

MAINJET

ADJUSTMENT

FUEL

BOWL

<,-

1

FLOAT

AXLE

OSITION HOOK UNDER TANG

ON FLOAT

SPRING AFTER

INSTALLATION

FIGURE

15.

SIDEDRAFT CARBURETOR ASSEMBLY

CHOKE.

FUEL INLET

VALVE

ASSEMBLY

THROTTLE SHAFT

AND LEVER

ADJUSTMENT

ADJUSTMENT NEEDLE

THROTTLE PLATE

Q

FIGURE

14.

DOWNDRAFT LUA CARBURETOR ASSEMBLY

t

9

FLOAT ASSEMBLY

NEEDLE VALVE

I

I/

I

FIXED

FS-1440-3

FIGURE

16.

CARBURETOR ASSEMBLY

VY

1

8.

.

FUEL

PUMPS

These engines are equipped with either a mechanical fuel pump, pulsating diaphragm fuel pump (pulse pump), or a remote electric fuel pump. Mechanical pumps are mounted on top of the engine crankcase,

in front of the carburetor. Pulse pumps are mounted

on the upper right corner of the engine blower hous-

ing on

NHC

engines and on the engine rear housing

on

NHCV

engines (Figure

17).

'

Pulse Pump Test Procedure

Before testing make certain that fuel pump vacuum line connections are tight and free

of

leaks.

1.

Operate engine at an idle for five minutes to ensure that carburetor is full of fuel.

2.

Shut engine off and remove fuel inlet line from fuel pump.

PUMP MOUNTS ON

NHC BLOWER HOUSING

PUMP MOUNTS ON NHCV

ENGINE REAR HOUSING

FIGURE

17.

PULSE

PUMP

LOCATIONS

Mechanical Fuel

Pump

Test

This type of pump can be tested for proper operation

by checking for fuel flow to the carburetor. Proceed

as follows:

Gasoline is highly flammable and

laWARNlNGl

potentially explosive! Use extreme

care when performing this test. Direct fuel flow into a suitable container and make sure area is well ventilated to prevenf accumulation of gasoline fumes.

1.

Remove the fuel line from the pump outlet or at

the carburetor inlet.

2.

Using some type of container to catch the fuel, crank the engine over several times. If the engine is a manual start, operate the pump priming lever instead. If the pump is electric, simply turn the ignition switch on to activate the pump.

3.

Fuel should spurt out. If

it

does not, be sure the problem is not an empty orshutoff fuel tank; then, remove the pump for repair or replacement.

Spilled fuelcan ignite and cause

k!@@%!l

serious personalinjury or death.

Thoroughly clean-up any spilled fuel.

3.

Connect avacuum gauge tofuel pump inlet using a piece of fuel hose with clamps.

4.

Start engine and allow to idle for five seconds. Record vacuum gauge reading.

5.

Move throttle control to high idle position. Wait five

;

seconds and record vacuum gauge reading.

6.

Shut engine

off

and remove vacuum gauge hose from fuel pump inlet. Connect fuel inlet line to fuel pump.

7.

Remove fuel outlet line from fuel pump.

Spilled fuel can ignite and cause serious personalinjury or death.

Thoroughly clean-up any spilled fuel.

8.

Connect a pressure gauge to fuel pump outlet using a piece of fuel hose with clamps.

9.

Start engine and allow to idle forfive seconds. While holding pressure gauge level with pump outlet record pressure gauge reading.

10.

Move throttle control

to

high idle position and allow engine to run for five seconds. While holding pressure gauge level with pump outlet, record pressure gauge reading.

.

11.

Shut engine off and remove pressure gauge hose

from fuel pump outlet. Connect fuel outlet line

to

fuel pump.

19

Repair or replace the fuel pump if test readings are not

within the values specified in

TABLE

1.

TABLE

1

PULSE PUMP TEST SPECIFICATIONS

Engine

Speed

Low

Idle

High Idle

Pump Inlet Pump Outlet

Vacuum Pressure

(Minimum) (Minimum)

2.6

inches

1.7

psi

of

mercury

2.6

inches

1.7

psi

of

mercurv

I

1

Pulse

Pump Repair

This section applies only to Facet fuel pump. The Nikki fuel pump is not repairable; replace unit if test readings are not within the values specified in Table

1.

Remove the vacuum and fuel lines. Inspect the lines

for wear, cracking, and brittleness. Replace as

necessary.

2.

To

insure correct alignment when reassembling, scribe a line across the outer pump parts on each end

of

the pump (Figure

17).

3.

Holding the pump carefully, remove the assembly

screws.

4.

Carefully pull apartthe pumpsectionsand checkfor worn or damaged parts. Replace with new parts where necessary or install pump repair kit (Fig-

ure

18).

ASSEMBLY

SCREWS

PUMP

COVER GASKET

5.

Checkand unclog

(if

necessary) thesmall diaphragm air bleed hole located behind the pump diaphragm in the pump base (Figure

18).

-1

A

clogged diaphragm air bleed

hole can cause diaphragm wear and seal damage while inhibiting pump operation.

d

6.

Replace gaskets and reassemble pump. Reinstall assembly screws, checking the scribe marks for proper alignment. Reinstall fuel and vacuum lines and clamps.

.

Use care when reassembling

and reinstalling fhe pump.

/mproper parts alignmenf or misconnecfed fuel lines can result in reaking fuel, creating a serious

fire hazard.

Mechanical Pump Removal and Repair

Removal:

1.

Remove the fuel inlet and outlet lines from the Pump.

2.

Remove the two capscrews holding the pump to the engine.

3.

Remove the pump, spacer (if used) and gasket from the engine and discard the gasket.

REED

VALVE

FIGURE

18.

EXPLODED

VIEW OF FACET PULSE PUMP

20

Repair:

Repair kits are available that provide replacements for those parts of the pump most subject to wear. If the operator chooses to repair the pump rather than install a new one, the use of all parts included in the

repair kit is recommended. Proceed as follows:

1.

After the pump is removed from the engine, scribealineon theflangesoftheupperand lower pump bodies to assure correct positioning when reassembling.

2.

Remove the securing screws and separate the upper and lower pump bodies.

3.

Detach the valve cage retainer from the pump

upper body. Noting their position, remove the valve and cageassemblies and their gasket sfrom the retainer (Figure

19).

UPPER PUMP BODY

8R

LOWER SIDE

DIAPHRAGM CASK

IAPHRAGM

RETURN

ROCKER

AR

ROCKER

ARM

LIN

PRIMING

LEV

FIGURE

19.

MECHANICAL FUEL PUMP - EXPLODED VIEW

4.

5.

tweezers to compress the spring and tip

it

off the rocker arm catch. When installing the newspring, make sure it is properly placed before remount-

.

ing the pump.

6.

Clean

in

solvent all pump parts that will not be

replaced and allow to dry.

7.

Install the new valve and cage assemblies and

their gaskets in the retainer.

Be

sure the assem-

blies are in proper position and fully seated. Reinstall the retainer and assemblies in the pump upper body.

8.

To install the new pump diaphragm, turn the

pump lower body upside-down and place the

diaphragm and spring in the body. Press the base

of the diaphragm up into the body of the pump

and turn

1/4

turn.

.

9.

Install new rocker arm return spring. Check for

proper spring placement.

10.

Place the upper and lower bodies

of

the pump

together with the scribe marks aligned. Start the four securing screws, making sure they do not

chew into thediaphragm fabric. Leave thescrews

2

or 3 turns loose.

11.

Operate the rocker arm several times

to

flex the

new diaphragm fully. While holding the rocker arm fully flexed, tighten the body screws.

-1

Failure

to

flex fhe rocker arm

fully while tighfening fhe pump bodies together will result in excessive pump pressure and possible engine flooding or pump diaphmgm failure.

Installation:

1.

Remove all gasket material from mounting faces and spacer (if used). Apply oil-resistant sealer to both sides of the gasket(s) and

to

the threads

of

the attaching capscrews.

2.

Place the gasket (and spacer if used) on the mounting face of the pump. Slide the mounting capscrews through the pump and gasket (and

spacer) to prevent thegasketfromslipping out

of

place.

3.

Lightly place the pump

in

position on the engine, making sure the rocker arm is riding o,n the camshaft lobe. Start both capscrews and check for proper gasket placement.

Detach the pump diaphragm by pressing its metal base into the pump body and turning it

1/4

turn.

The rocker arm return spring can normally be

removed without removal of the rocker arm from

the pump body. Use a small screwdriver or

4.

Connect the fuel inlet and outlet lines.

5.

Operate the engine and check for leaks.

.

21

Electric Fuel

Pump

All engines used on Onan N series generator sets are equipped with an electric fuel pump. The pump is

manufactured by Facet (a division of Bendix Corpo-

ration) and carries a Facet nameplate. An internal fuel shutoff valve is a standard feature on this pump. Older versions

of

this pump carry the Bendix name-

plate and do not have an internal fuel shutoff valve. Service proceduresforthe Facet or Bendix pump are the same.

Do

not substitute automotive type

laWAR”Gl

electric fuel pumps for standard

Onan supplied electric pumps. The

output

pressure

is much higher and can cause carburetor flooding

or

fuel

leakage, creafing a fire hazard.

Pump

Tesf:Test the fuel pump by checking the pump

outlet pressure. Use the following procedure.

1.

2.

3.

Remove the fuel line from the pump outlet and install a pressure gauge.

Press the START switch and hold

it

for several

seconds until pressure reading is constant.

Pressure reading should be 2-1/2 to

3-1/4

psi (17.2 to 22.4 kPa). If the retension is good, the pressure should stay constant or drop

off

very

slowly.

A low pressure reading with little or no pressure drop indicates a weak or broken diaphragm or diaphragm

spring, worn linkage,or leaky check valves. If pressure

is above maximum, the pump diaphragm is too tight or the diaphragm (or plunger) return spring is too strong. Any of the above conditions are cause for

repair or replacement of the pump.

Fuel Pump Repair:

Service of the Facet pump

is

limited to the bottom cover, filter, plunger tube, and plunger assembly. All parts

of

the electric system are hermetically sealed in a gas atmosphere and are not serviceable. If electrical failure occurs, replace the

Pump.

Do

not tamper with the seal at the

@%@@

cenfer

of

fhe mounting bracket

on

the side of the pump as

if

retains the dry gas which

surrounds fhe electrical system. Electrical system

components are nof serviceable.

Use the following procedure for servicing the pump:

1.

Using a5/8-inch wrench, loosen, the pump cover,

then remove by hand.

2. Remove the filter, magnet and cover gasket (Figure 20).

PUMP ASSEMBLY

I

3.

FS-1487

FIGURE

20.

REMOVAL

OF

MAGNET AND FILTER

Using a thin

nose

pliers, remove the retainer

spring from the plungertube. Remove the washer,

“0”

ring seal, cup valve, plunger spring and

plunger from tube (Figure

21).

PUMP ASSEMBLY

PLU

N,GER

FS-1486

FIGURE

21.

REMOVAL

OF

PLUNGER ASSEMBLY

4.

22

Wash all parts (except gasket and seal) in parts cleaning solvent. Blow out solvent and dirt with low pressure compressed air. Slosh the pump assembly

in

cleaning solvent, blow dry and

swab

the inside of the plunger tube with acloth wrapped

around astick. lfthe plungerdoes notwash clean or has rough spots, gently clean the surface with crocus cloth.

Most parts cleaning solvents are flammable and can cause

serious personnel injury

if

used improperly.

Fol-

low fhe manufacturer‘s recommendafions when cleaning

parts.

5.

Insert plunger in tube, buffer spring end first. Check fit by slowly sliding the plunger back and

forth in the tube.

It

should move fully without any tendency tostick. If aclick cannot be heard as the plunger is slid from one end to the other, the internal pump assembly

is

not functioning prop-

erly and the pump should be replaced.

6.

Install plunger spring, cup valve,

“0”

ring seal

and washer. Compress the spring and install the

retainer with ends in the side holes of the tube.

7.

Check cover gasket and replace if deteriorated. Place cover gasket and magnet in the bottom cover and install filter and cover assembly on pump. Twist cover on by hand and tighten

securely with a 5/8-inch wrench.

---

.

Fuel

Shutoff

Valve

(When

Used)

The external fuel shutoff prevents fuel flow into the

carburetor after engine shutdown. It connects electrically to the ignition power terminal and energizes during engine cranking and running to allow fuel flow.Thedevicefastens directly to the fuel pump inlet

(Figure

22).

USED WITH

PUMPSTHAT

DO

NOT HAVE

AN INTERNAL

SHUTOFF

VALVE

FS-1485

To

test

the

solenoid, connect a jumper wire from

the

B+

terminal on the control box to the plus

(+)

side

of

the ignition coil. If thesolenoid is good, aclickshould

be heard when the

wire

makes

contact.

-1

Twisfing the body

of

the solenoid

.

will cause infernal damage. Apply

twisting

force with a wrench only

at

fbe hex nut

locafed near fbe fuel inlef.

Fuel

Filters

Facet/Bendix Fuel pumps incorporate a filter within the casing of the pump (Figure

23).

Use a

5/8

inch

wrench to twist off the bottom

of

the pump and

remove the filter element. If thefilter is dirty, replace

it

along with the cover gasket.

GASKET

FIGURE

22.

FUEL SOLENOID

FIGURE

23.

BENDIX

AND

FACET ELECTRIC

PUMP

FILTER

23

ELECTRIC CHOKE

The choke consists of a bi-metal coil and an electric

heating element. The bi-metal coil connects to the choke shaft and holds the choke plate nearly closed

when the engine is cold.

As

the engine starts, current is supplied to theelectric heating element in the choke cover. Heat from the element causes the bi-metal coil to twist. The twisting action of the coil turns the choke valve shaft and gradually opens the valve. Heat from the element keeps the choke open while the engine is running.

The choke cover gefs very hot during normal operation and can cause

serious

burns

if

touched.

Do

nof

touch the choke

cover while the set is operating.

~

AVERAGE

CHOKE

SETTING

Ambient Temp

Choke

Opening

58'

(14OC)

closed

66'

(19OC) 114

open

72' (22OC)

1

I2

open

76'

(24OC) 314

open

82' (28OC)

open

If the engine starts but runs roughly and blows out

black smoke after a minute or two of operation, the choke is set too rich. If the engine starts but sputters or stops before it warms up, the choke is set too lean.

Adjustment

Table 2 lists average choke settings. Loosen the

two

mounting screws and rotate the choke cover until the correct setting

is

attained. Check the setting by starting

the engine and observing its operation. Be sure to

retighten the mounting screws after adjustment (Figure

24).

TABLE

2.

CHOKE SPECIFICATIONS

BI-METAL COIL

n

CATCH OUTER END

OF

COIL

IN

SLOT

IN

COVER TAB

COVER

MOUNTING

SCREWS

FS

1484

LOOSEN THESE

RICHER

MIXTURE

FIGURE

24.

ELECTRIC

CHOKE

ADJUSTMENT

Repair

If the choke fails to operate, check to see if the heating element isworking. If it is, thechokecovershould become hot after afew minutes of engine operation. If the cover does not get hot, check for current at the cover terminal. The engine must be running. Trace down any opens or shorts.

Remove the choke cover to inspect

the

heating element and coil. See that the element is not burned out or broken. The bi-metal coil must not be damaged, dragging in the housing, or have an improperly directed spiral.

When installing a new coil, maintain the original direction of spiral inward from the fastening screw. Be sure the coil sets squarely in the housing

so

it will

not bind.

Coil

should not touch inside of choke body.

24

AIR

CLEANER

.

If

air cleaner becomes too

dirty,

liGEEi

engine wil/

not

receive sufficient air

to

run

properly. Symptoms:

Loss

of power, flooding,

hard starting, and overheating.

Engine is equipped with a paper element.

If

the engine is equipped with polyurethane precleaner it must be removed, cleaned, and oiled every

25

hours

of

operation, or more often under extremely dusty

conditions.

1.

To clean precleaner wash in water and detergent (Figure

25).

Remove excess water by squeezing

like a sponge and allow

to

dry thoroughly.

2.

Distribute two tablespoons

of

SAE

30

engine oil evenly around the precleaner. Knead into precleaner and wring out excess oil.

3.

Depending on conditions in which the engine is operating, the inner paper element should be replaced whenever it becomes excessively dirty or oily.

Neverrun engine

with

air cleaner

~ACAUTloN

1

removed.

Dirt

will enter engine

and wear

out

rings causing excessive blow-by.

pp-

WING NUT

COVER

POLYURETHANE

PRE-CLEANER

PAPER

ELEMENT

BASE

1.

WASH

2.

SQUEEZE

DRY

3.

COAT WITH OIL

3.

INSTALL OVER

PAPER ELEMENT

FIGURE

25.

AIR

CLEANER

ASSEMBLY

25

GOVERNOR ADJUSTMENT

Where engine speed is governor controlled, the governor is set at the factory to allow a nominal engine speed of

2400

rpm at no load operation (unless another speed is specified when the engine is ordered). Proper governor adjustment is one of the

most important factors in maintaining the power and

speed desired from the engine.

Before making governor adjustment, run the engine in a well ventilated area for about 15 minutes to reach normal operating temperature.

It

is difficult to determine if, after long usage, the governor spring has become fatigued. If, after properly making all other adjustments, the regulation is still erratic, install a new spring (Figures

26

and 27).

A tachometer for checking engine speed is required for accurate governor adjustment.

Check the governor arm, linkage, throttle shaft, and

!

lever for binding or excessive wear at connecting points. A binding condition at any point

will

cause the

governor

to

act slowly and regulation will be poor.

Excessive looseness

will

cause a hunting condition, and regulation will be erratic. Work the arm back and forth several times by hand while the engine idles.

If

either of these conditions exist, determine the cause and adjust or replace parts as needed.

THIS

DISTANCE DETERMINES SENSlTiVlTY

MORE

4

1

SENSITIVE

I

LESS

I

SENSITIVE

Procedure

1. Adjust the carburetor main jet for the best fuel

2.

Adjust the carburetor idle needle with no load

3.

Adjust the length of the governor linkage.

4.

Check the governor linkage and throttle shaft for binding or excessive looseness.

5.

Adjust the governor spring tension for nominal engine speed at no load operation.

6.

Check the rpm drop between no load and full load

operation, and adjust the governor sensitivity as

needed (should be about

8%).

7.

Recheck the speed adjustment.

8.

Set the carburetor throttle stop screw.

mixture at full load operation. connected.

Linkage

The engine starts

at

wide open throttle. The length

of

the linkageconnecting the governor arm

to

the throttle arm is adjusted by rotating the ball joint housing. Adjust the length

so

that with theenginestopped and

tension on the governor spring, the stop on the car-

buretor throttle lever is 1/32 inch

(0.794

mm) from the carburetor stop boss. This setting allows immediate control by the governor after starting and synchronizes travel of the governor arm and the throttle shaft.

THROTTLE

ARM

CARBURETOR

THROTTLE

JOINT

BALL

kt

\\

SHAFT

SPRING STING

STUD

-GOVERNOR

ADJUSTMENT

FIGURE

26.

GOVERNOR ADJUSTMENTS

26

DECREASE SPEED

INCREASE SPEED

.

GOVERNO~

ARM

//

EXTENSION

t

MAXIMUM

DEGREASE

SPEED

SPEED STOP

$1

&GOVERNOR

L

MINIMUM SPEED

STOP

-

FIGURE

27.

VARIABLE

SPEED

GOVERNORS

Speed Adjustment

The speed at which the engine operates is determined

by the tension applied

to

the governor spring. Increasing spring tension increases engine speed. Decreasing spring tension decreases engine speed. The no load speed of the engine should be slightly higher than the speed requirements of the connected load. For example,

if the connected load is to turn at 3510 rpm, set the no-load speed of the engine at about 3600 rpm. Check

speed with a tachometer. If aspeed adjustment is needed, turn the speed adjusting

nut in to increasethespeed orouttodecreasethespeed (Figure

26).

Sensitivity Adjustment

The engine speed drop from no-load

to full-load

should

not be more than

400

rpm. Check the engine speed with no load connected and again after connecting full load. Do not exceed rated rpm at no-load.

The sensitivity of the governor depends upon the position of the arm end of the governor spring.

A

series of holes in the governor arm provides foradjustment.To increase sensitivity, move the spring toward the governor shaft. To decrease sensitivity, move the spring toward the linkage end of the governor arm.

If

the setting

is

too sensitive, a hunting condition (alternate increase and decrease in engine speed) will result. If the setting is not sensitive enough, the speed variation between no-load and full-load conditions will be too great Therefore, the correct sensitivity will result in the most stable speed regulation without causing a surge condition.

Always recheck the speed adjustment after a sensitivity adjustment. Increasing sensitivity

will

cause a slight decrease in speed and will require a slight increase in the governor spring tension.

Variable Speed Governor Adjustment

These engines are adapted for use where a wide range of speed settings is desired. The design of the variable speed governors gives an automatic increase in sensitivity when the speed is increased and the result is good stability at all speeds.

27

I

JNKABE

To adjust the variable speed governors, refer to Figure

27

and the following:

1.

2.

3.

4.

5.

Run the engine and make necessary carburetor adjustments.

Adjust the throttle stop screw on the carburetor to allow a recommended minimum idling speed of 1100 rpm.

A

lower minimum does not assure smooth

operation under load. Adjust the tension of the governor spring for

minimum speed. For governors having a manual control arm, set

lever to minimum speed with no load and adjust the spring tension for about 1500 rpm.

For governors having a Bowdin wire remote control knob

(NHC

engines with mounted engine controls), pull back the knob and slide to the first notch (low speed). Adjust speed to about

1500

rpm (or the desired low speed) at no load by turning the knob as required.

Adjust the sensitivity while operating at minimum speed to attain the smoothest no load to full load operation as follows:

To

decrease sensifivity (allow more speed drop

from no-load to full-load operation), move the

governor spring outward into a different groove or hole in the extension arm.

To

increase sensitivity (closer regulation by the governor which permits less speed drop from noload to full-load operation), move the governor spring inward into a different groove or hole in the extension arm.

Apply a full load and shift the variable control to maximum speed-moving the control arm to the right or shifting the control knob and slide to the second notch. For the governor control with the control arm, set the screw

in

the bracket slot to stop lever travel at the desired maximum full-load speed position. For the control with the control know and slide, increase or decrease speed by turning the knob as required.

Approximately3000 rpm is the recommended maximum

full-load speed for continuous operation. The speed

must agree with the load requirements.

Ignition and Battery Charging

IGNITION TIMING

.016

inch

(0.41

mm) by adiusting the socket head

Timing

is

preset

atthefactory.Slighttiming

changescan

be made by adjusting the points.

screw

(D)

inward or.o&.va;d (Fighe 28). Make sure

feeler gauge is clean and free of any grease, oil, or

dirt.

A

.016

inch point gap is equivalent to 20' BTC.

The engine is equipped with an automatic type battery ignition system. Both spark plugs fire simultaneously, thus the need for a distributor is eliminated.

7.

Replace breaker box cover, coil wire, spark plugs, and spark plug cables.

-

BREAKER

POINTS

The timing is adjusted during initial engine assembly and

is

fixed by the point gap adjustment. To maintain maximum engine efficiency, change the breaker points every 200 hours of operation.

Replacement and Adjustment

1.

Remove spark plugs.

2. Remove breaker box cover. Rotate crankshaft clockwise (facing flywheel) until points are fully open.

3.

Remove condenser (screw A) and detach condenser lead and coil lead screw (screw

B).

See

Figure 28.

4.

Remove two Allen screws

(C)

and lift breaker

assembly from engine.

5.

Replace condenser and point assembly with new

parts and reinstall, using above procedure in

reverse order

of

removal.

6.

Adjust point gap by rotating crankshaft clockwise

(facing flywheel) by hand until the pointsarefully open.

Set

the point gap (using flat feeler gauge) at

Continuity Test

As a check for proper ignition timing a continuitytest may be performed:

1.

Adjust breaker points.

2.

Remove

air

intake hose or cylinder shroud to

expose timing marks (Figure 29).

3.

Rotate flywheel clockwise until timing mark is aligned with the mark corresponding to 20" BTC on top of gearcase cover.

4.

Connect an ohmmeter or a continuity test lamp set across the ignition breaker points. Touch one test prod to thecoil lead terminal (screw

B

Figure

28).

5.

Touch theothertest prod toagood ground on the engine.

6.

Turn crankshaft against rotation (counterclockwise) until the points close. Then slowly turn the crankshaft with rotation (clockwise).

7.

The lamp should go out (continuity lost) just as the points break, which is where ignition occurs.

If timing is early (advanced), the point gap is too large. If timing is late (retarded), the point gap

is

too

small. Adjust point gap accordingly.

n

POINTGAP.

!I

FIGURE

28.

SETTING

POINT

GAP

28

TIMING MARKS ON BLOWER HOUSING

--

POINTER

ON TIMING

FLY

W

H

EEL

8389

TIMING MARKS ON GEAR COVER - VIEW

__..

THRU BLOWER WHEEL

TIMING MARKS

0

GEAR

COVER

PRESSURE

COOLED

REMOVE AIR

INTA-KE

HOSE20

VlEWTlMlNG MARKS

.

TIMING MARK

ON FLYWHEEL

VACU FLO

ENGINES:

REMOVE AIR

SHROUD

FROM

RIGHT

CYLINDER TO VIEW TIMING MARKS

IGNITION

COIL

To

test primary and secondary windings within the

ignition coil proceed as

follows:

1.

Use a Sirnpson

260

VOM

or equivalent.

2.

Place black lead on ground (-)terminal

of

coil and

red lead to positive

(+)

terminal. Primary resist-

ance should read

3.87-4.73

ohms.

3.

Change resistance setting on ohmmeter. Place ohmmeter leads inside of spark plug cable holes (Figure

30).

Secondary resistance should read

12,600-15,400

ohms.

4.

If any

of

the above conditions are not met, replace

coil. Refer to

PARTS

CATALOG

for correct part

number:

FIGURE 30. COILTEST

SPARK’PLUGS

Check, and regap spark plugs every

100

hours of

operation (Figure

31).

Replace spark plugs that show

signs of fouling or electrode erosion.

FIGURE

29.

TIMING

MARK

LOCATIONS

FIGURE

31.

SPARK PLUG GAP

29

BATTERY INSPECTION BATTERY

JUMP

STARTING

Check battery cells with a hydrometer. The specific gravity reading should be approximately

1.260

at

77"

F

(25OC),

Figure 32.

Occasionally, it may be necessary to jump start a weak battery using a charged booster battery to start your engine. If jumpstarting is necessary, the follow-

ing procedure is recommended in order to prevent

starter damage, battery damage and personal injuries.

RAVITY READING

260

AT

77

F

(25

C)

FIGURE

32.

SPECIFIC GRAVITY

TEST

6

Do not engage starter for periods longer than

30

seconds without

allowing

5

minutes for starter

to

cool. Starter failure

may result if these guidelines are not followed.

.

1.

Disconnect engine load.

2.

Use only a battery of the same voltage

(12V)

as is

used with your engine.

3.

Attach one end

of

the positive booster cable (red)

to the positive

(+)

terminal of the booster battery.

Attach the other end of the positive cable to the

positive

(+)

terminal

of

your engine battery.

4.

Attach one end of the negative

(-)

booster cable

(black) to negative (-)terminal of booster battery.

Attach other end of negative cable to a solid

chassis ground on your engine.

Arcing may cause severe per-

-

sonal injury.

Do

not allow the

If

one or more cells are low on water, add distilled water and recharge. Keep the battery case clean and dry. An accumulation of moisture will lead to a more

rapid discharge and battery failure.

positive and negative cableends

to

touch each other because it will short the battery causing arcing.

I

Keep the battery terminals clean and tight. Push the cable terminal down flush with or slightly below the top

of

the battery post (Figure33). After making con-

nections, coat the terminals with a light application of

petroleum jelly or grease to retard corrosion.

r

BATTERY POST

CABLE TERMINAL

b

FIGURE

33.

BAlTERY

CABLE

CONNECTION

Poor contact at the battery cable connections is often a source of trouble. Make sure battery cables are in good condition and that contacting surfaces are clean and tightly connected.

Do

not reverse battery leads. Use recommended battery tools when disconnecting leads to avoid physical damage to battery.

5.

Jump starting in any other manner may result in damage to the battery or the electrical system.

6.

Turn ignition switch to

ON

to start engine.

Jump starting a frozen battery

can explode and can cause severe personal injury. Never jump start a frozen battery.

To

do

so

may cause the battery

to

explode. Never expose the battery

to

an open flame or an electrical spark because a battery discharges highly explosive hydrogen gas.

FLYWHEEL ALTERNATOR

The flywheel alternator is a permanent magnet alternator and uses asolid-state voltage regulator-rectifier for controlling output.

Three different alternator systems are used with

NHC

and NHCV engines;

20

amp Synchro system,

15

amp

Phelon system,

20

amp Phelon system.

Weak ignition spark ora discharged battery indicates trouble in the charging system. But before testing engine charging system, always check the battery for serviceability.

AWARN~NG

Do

not smoke while servicing bafter-

m

ies.

Explosive gases are emitted from batteries while charging. Ignition of these gases can cause severe personal injury.

This engine uses a

12

volt, negative

ground system. Alternator must

be

connected

to

battery at all times when engine

is

run-

ning.

Do

not

reverse batfery cables.

30

RECTIFIER

STATOR

ASSY.

I

TO

BATTERY

SCREEN

BOLT

FLYWHEEL

ON

PRESSURE COOLE

'ACU-FLO

ENGINE

\

FLYWHEEL

ALTERNATORROTOR

(PART OF FLYWHEEL

ASSY.)

FIGURE

34.

20

AMP

SYSTEM

TESTING

OR

SERVICING

Keep these points in mind when testing or servicing the

flywheel alternator:

1. Be sure engine

is

being run long enough and fast enough to recharge battery after each start Alternator output is reduced in direct proportion to engine rpm. Also, power required for accessories reduces power available

to

recharge battery.

2.

Be sure output control plug (connector) is inserted properly. Plug must bottom in receptacle-eliminates any resistance due to a poor connection. Keep clean and tight.

3.

Make sure alternator stator leads are not shorted

together.

4.

Be sure regulator-rectifier output control has a good ground connection. Mating surface for mounting must be clean and fasteners tightened properly.

5.

Never reverse the battery leads.

6.

Charging system tests require a fully charged battery.

20

Amp

Synchro

System

The

20

amp flywheel alternator systems use a separate

regulator and a separate rectifier, Figure

34.

Testing:

For testing this system, use a voltmeterohmmeter such as a Simpson 270. Various alternator problems with individual test procedures are listed in Table

2.

TABLE 2.

TESTING

SYNCHRO

20

AMP

SYSTEM

TEST

Battery voltage - unit not running

Battery voltage with unit running at 1800 rpm or more

VALUE

AC voltage from stator with plug disconnected and unit running at approximately

1800

rpm

Ohmmeter reading at plug when checking

two

AC

stator leads - unit not

running

Resistance values

(Ohms)

are as

follows

between

wire

pairs

1

BLACK

I

.S

-

17

n

1.8-

2.2n

I

t

BLACK

1.3-

1.5a

12 Volts DC

14.2

-

14.8VDC

depending on

charge condition

of battery

23

VAC

minimum*

Black to Black

'

-

48

VAC

maximum

at

3600

rpm.

31

No

Output-Stator Assembly:

Examine leadwires for loose or broken connections at the regulator and rectifier. Use the

Rxl

scale on the ohmmeter for

detecting opens in the stator. Disconnectthe three wires

that come from alternator stator

(two

black, one red). Connect ohmmeter test leads to red leadwire and ground to check continuity. The ohmmeter reading should be about 2.0 ohms. See Figure 34a for wiring diagram.

Next, connect meter to black leadwires and ground. Approximately0.1 ohm should be read from either black lead to ground. If no continuity exists between ground and black leads, stator assembly should be replaced.

ALTERNATOR STATOR

MOUNTED BEHIND BLOWER WHEEL

\n

TO TERMINAL

CONNECTOR

RECTIFIER

ASSEMBLY ASSEMBLY

I

--

-

FIGURE

34a.

20

AMP

SYNCHRO

SYSTEM

Checking RectifierAssembly:

Examine each of the

two

diodes for breakdown by connecting ohmmeter (Rxl

scale) from one black lead to white lead. Meter should

read 10 ohms in proper polarity. A shorted diode would read zero resistance and would cause a short circuit

through the lead winding when in operation. An open diode would read infinite in both directions indicating that replacement is necessary.

Testing Regulator Assembly:

To check for proper voltage regulation, attach a DC voltmeter to battery and operate engine at about 1800 rpm. Battery voltage will climb to the preset factory setting

(14.2

to 14.8 volts).

Some installations may vary due to voltage drop in the length of ammeter harnesses. Other variations may stem from a loose connector

in

the harness or loose or corroded battery leads. Low voltage readings at the battery mean poor battery connections.

To test regulator, remove connector. Using the Rxl0,OOO scale of your ohmmeter, connect one meter lead to red leadwire and other meter lead to regulator base.

No

deflection should be noted on the ohmmeter in either

polarity. Next, connect meter to black leadwire and base

of regulator. Meter will deflect fully in one polarity, with

no deflection in the other.

Full

Charge-

Will

Not Regulate:

Check for broken

leads at connection to regulator plates. To be sure

regulator winding operates properly, connect red lead

to ground and start engine.

A

maximum of 4 amperes

should be noted. This would indicate stator winding is

satisfactory. if

so,

replace regulator.

No

Charge:

If alternator does not charge when load is

applied to battery, shut

off

engine and disconnect one

red leadwire from regulator terminal. Be sure lead is taped or isolated from conducting engine parts. Once again, start engine. Alternator should charge to full output; if

it

does not, replace stator assembly.

6

15

Amp Phelon System

The Phelon flywheel alternator systems (Figure

35)

have

as one piece regulator-rectifier assembly. Various alter-

nator tests are listed in Table

3.

With the engine running between 1800 to 2600 rpm, observe the panel ammeter (if not already equipped, connect a test ammeter).

If

no charging is evident,

proceed with the

Alternator

Output

Test,

Alternator Output

Test

... . . . .

1.

With the engine running, check the battery terminal voltage (regulator output) using a DC voltmeter. Voltage output should be within thevaluesspecified in Table

3.

If voltage is greater than specified

replace regulator-rectifier assembly.

If

voltage is

less than specified, proceed to step

2.

Examine all wires for loose, corroded, broken connections, short circuits, etc. Check fuses. Repair as needed to assure complete circuits from regulator-

rectifier

B+

terminal to battery positive

(+)

terminal

and from battery negative

(-)

terminal to regulator-

rectifier case.

If

battery voltage remains low with

engine running, proceed

to

step

3.

Disconnect plug from regulator-rectifier and test

the

AC

voltage at the plug with engine running near 3600 rpm. If AC voltage reads more or less than specified in Table 3, proceed to step 4. If ACvoltage

is as specified but

DC

voltage is low, replace

reg ulator-rectifier.

4.

Use the Rxl scale on the ohmmeter for detecting opens in the stator (unit not running). Disconnect plug from regulator-rectifier. Connect ohmmeter

test leads

to

wires coming from stator. Refer to

Table

3

for

resistancespecifications.

If resistance is not as specified, replace stator. If stator resistance readings are as specified and windings are not shorted to ground, low AC voltage may be due to loss of magnetism. If

so,

blower wheel assembly must be replaced. Check for magnetism with steel tool blade. Next, connect one ohmmeter test lead to stator wire, connect the other test lead to gorund. If the ohmmeter reading is low the stator

is

grounded

and must be replaced.

32

TABLE

3.

TESTING PHELON SYSTEMS

BASIC

TEST

1.

Battery

TEST

VALUES

PROCEDURE

1

SA.

SYSTEM

20A.

SYSTEM

Battery Voltage - unit not running.

12

VDC

12

VDC

2.

Regulator

3.

Alternator Stator

and Wiring

4.

Alternator and Wiring

MOUNTED ON

CYLINDER COVER

\

VR1

Battery Voltage after unit is running

3

to 5 minutes.

Ohmmeter reading from stator

output

-

unit not running.

Check at plug.

Measure

AC

open circuit stator voltage with unit running. Measure between two stator leads with

23

VAC minimum

plug disconnected and unit

65

VAC maximum

48

VAC maximum

running at approximately

3600

rpm.

13.6

to

14.7

VDC

13.6

to

14.7

VDC

0.1

to

0.2

Ohms

0.3

to

0.5

Ohms

28

VAC

minimum

MOUNTED BEHIND

BLOWER WHEEL

AC

B+

AC

FLYWHEEL

VOLTAGE REGULATOR

85-1333

TO BATTERY

-

AC -AC

15 AMP

20

AMP

CAUTION:

REGULATOR MUST BE GROUNDED

THROUGH MOUNTING BOLTS

151332

VOLTAGE REGULATOR

CONNECTIONS

FIGURE

35.

PHELON SYSTEM

33

Starting

System

ELECTRIC STARTER

The electric starter contains three main assemblies: an electric starting motor; a pinion gear and clutch which engages with the ring gear on the engine flywheel during starting; and a solenoid-switch assembly which shifts the pinion gear into the engine

ring gear and activates the starting motor.

The starter will seldom require service other than

possible brush replacement. Before attempting starter repair, make sure the electrical system leading to the start solenoid

is

not the source of the problem. If thestarter bindsorslipsduring cranking, or isexcessively noisy, the gear lash between the starterand the flywheel ring gear may be incorrect. Information on setting the gear lash is provided at the end of this section.

FIGURE

36.

STARTER ASSEMBLIES

STARTER DISASSEMBLY

AND

REPAIR

Starter disassembly and inspection procedures are provided below. Common sources of starter malfunction include worn commutator brushes, worn armature bearings, a stripped pinion gear, or a faulty solenoid-switch.

Removal

1.

Disconnect the positive battery cable from the

2.

Remove the blower housing from the front of the

3.

Holding the starter in place, remove the starter

starter solenoid-switch. engine. mounting bolts, then remove the starter.

Disassembly

Some differences in configuration exist between the starter used during Spec Aand the starterthat has been

used from Spec

B

to the present (Figure

36).

However, disassembly procedures for either are basically the same. Using Figure

37

as a guide, proceed as follows:

I.

Remove the field coil strap where

it

connects to

the solenoid-switch.

2.

Detach the mounting screws, and remove the

solenoid-switch from the starter motor.

3.

Remove the starter thru-bolts. Separate the front bracket from the starter housing. The solenoid

shift lever and spring components will come

loose as the front bracket is removed. The arma-

ture may also be removed from the starter hous-

ing at this time.

4.

Remove the brush holder retaining screws from the back of the rear bracket. Separate the rear bracket from the starter housing and the

brush

holder.

5.

To

remove the pinion gear and clutch from the armature shaft, drive the pinion stopper away from the retaining ring

it

holds in place (Figure

38).

Remove the retaining ring and slide the pinion

stopper, pinion gear and clutch

off

of

the armature

shaft

L

Inspection

of

Parts

Pinion

Gear

and

C/ufch:

The pinion gear should

rotate smoothly (not necessarily easily) in one direc-

tion and not at all in the opposite direction. If the gear

isworn or burred, or does not rotate properly, replace the gear and clutch assembly. Also check the teeth on theflywheel ring gearfor signs of excessive wearand

replace if necessary.

34

SOLENOID-SWITCH FIELD COIL

842,

FRONT

BRACKET

FIGURE

37.

EXPLODEDWEW

OF

STARTER (BEGIN SPEC

B)

ASSEMBLY

PINION STOPPER

CYLINDRICAL TOOL

Measure the brush spring tension by placing the brush holder assembly in place over the commutator end

of

the armature. Hook a spring scale over the spring nearthe brush and take a reading as the spring just leaves the brush. On a new brush, the tension

DRIVE PINION STOPPER AWAY FROM RETAINING RING WITH CYLINDRICAL TOOL

'

ES-1022

FIGURE

38.

PINION GEAR AND CLUTCH REMOVAL

Brush

Inspection:

When brushes are worn to the wear limits (Figure 39), replace them. See that the brushes move smoothly in the brushholders.

.-

_.

FIGURE

39.

BRUSH WEAR LIMITS

should be

49

to 59 ounces (1390 to 1670 grams). For

the Spec

A

starter, the tension shoud be 29 to 38

ounces (820 to 1075 grams).

Tesfing

Armafure

for

a

Short

Circuit:

Use a growler

for locating shorts

in

the armature. Place armature

in

growler and hold a thin steel blade (e.g. hacksaw blade) parallel to the core and just above

it

while

slowly rotating armature in growler.

A

shorted armaturewill cause the bladetovibrateand be attracted to the core. If armature is shorted, replace with a new one (Figure

40).

.

FIGURE

40.

ARMATURE

SHORT

CIRCUIT TEST

35

Testing Armature

for

Grounds:Touch armature shaft or

core and the end

of

each commutator bar with a pair of

ohmmeter leads (Figure

41).

If the ohmmeter reading is

low, it indicates a grounded armature. Replace a

grounded armature.

Testing

Field

Coils

for

Open

Circuifs:

Place one lead on the connector and the other on a clean spot on the brushholder (Figure

43).

A high ohmmeter reading indicates the field coil is open. Check the other three brushholders in the same manner.

COMMUTATOR.

..

~-_____

._

FIGURE

41.

ARMATURE GROUND TEST

lnspecfing

for

an

Open Circuit

in

Armafure:The most

commutator riser bars. Inspect for loose connections

on the points where the conductors are joined to the commutator bars.

Testing Field

Coils

for

Grounds:

Place one lead on

the connector and the other on a clean spot

on

the

frame after unsoldering the shunt field coil wire (Fig-

ure42).Alowohmmeter reading indicatesagrounded

field either at the connector or in the windings.

likely place to check for an open circuit is at

the

FIGURE

43.

FIELD COIL OPEN CIRCUIT TEST

Testing

CommufaforRunouf: Place armature in a test

bench and check runout with a dial indicator (Figure

44).

When commutator runout exceeds

0.004

inch

(0.102

mm), reface the commutator.

.

FIGURE

42.

FIELD

COIL GROUND

TEST

FIGURE 44. CHECKING COMMUlTOR RUNOUT

36

Testing Armature

Shaff

Runout:

You can check the

armature shaft for runout as shown in Figure

45.

A

bent armature can often be straightened, but a new

armature

is

required if the shaft

is

worn.

FIGURE

45.

CHECKING ARMATURE SHAFT RUNOUT

CLEANING PARTS

1.

Do

not immerse parts in cleaning

(BCAUTIONI

solvent. Immersing the field coil, yoke assembly, armature, and solenoid will damage fhe insulafion. Wipe these parts with a cloth only.

2.

Do

nof

immerse fhe overrunning clutch in clean-

ing solvent- The clutch

is

prelubricafedat the factory,

and solvent will wash lube from clutch.

3.

Wash all other parts in solvent and dry.

STARTER ASSEMBLY

1.

Lubricate armature shaft with a very light grade

oil.

A

medium or heavy oil or grease may cause

faulty operation in cold weather.

2.

Slide the pinion gear and clutch assembly and the pinion stopper onto the armature shaft. Position

the retaining ring in its groove on the armature shaft, and secure the pinion stopper over it using a puller such as that shown in Figure 46.

3.

Apply a small amount of Lubriplate on the shift

lever pivot pin and lever holders (unless the holders are made

of

nylon, in which case no lub-

ricant

is

needed).

FIGURE

47.

SHIFT LEVER INSTALLATION

4. Place the shift lever assembly in position on the armature as shown in Figure 47. Slide the thrust

washer onto the end of the armature shaft, and

install the armature and shift lever assembly in

the front bracket (Figure 48).

FRONT

BRACKET

I

FIGURE

46.

ARMATURE INSTALLATION

PINION

STOPPER

..

,

-.

5.

Place the shift lever spring and spring holder in

the front bracket. Slide the starter housing over the armature and align with the front bracket.

6.

Position the brush holder and brushes in place on

the commutator end of the armature, pulling the

brushes back against spring tension to allow the holder to slide in place.

7.

Install the rear bracket making sure the thru-bolt

and brush holder screw holes are properly positioned. Slide thru-bolts into position and screw

in

place. Install the brush holder attaching screws.

8. Install thesolenoid-switch, catching the solenoid plunger on the solenoid shift lever.

FIGURE

46.

INSTALLING PINION GEAR

AND

CLUTCH

37

INSPECTION

AFTER

OVERHAUL

For no-load test, the starting motor is wired as

shown in Figure

49

and run. The value of the meter reading at this condition should be as follows:

Begin Spec

B

Voltage 10.5 11.5

RPM

5000

3700

Max. Current

Draw (Amp)

53

60

Spec A Only

1.

AMMETER

SWITCH

INDICATOR

FIGURE

49.

WIRING STARTER FOR NO-LOAD TESTS

The conductor for this test should be large enough in

diameter and as short as possible.

If

anything

is

wrong in

the above test, inspect the following items:

Annealed brush springs Improperly sealed brushes Insufficient armature endplay Shorted, open, or grounded armature Grounded or open field coil

Poor electrical connection

Dirty commutator

2.

To

adjust pinion clearance, connect the battery to thestarting motorasshown in Figure50.This will allow the pinion of the starting motor to slide and stop. In this state, measure the clearance between the end of the pinion and pinion stop when the

pinion

is

pushed lightly toward the commutator

end. Clearance should be

0.02

to

0.06

inch (0.51 to 1.52 mm). Adjust for proper clearance by removing the solenoid switch attaching screws and select the proper thickness of the fiber packings shown

in

Figure

51.

FIBER

PACKINGS

FIGURE

51.

ADJUSTING PINION CLEARANCE

CHECKING

GEAR

LASH

Always check starter-to-flywheel gear lash when reinstalling the starter on the engine. Lash should also be checked if the starter binds or slips during cranking or

is

excessively noisy. Proceed as follows:

1.

2.

3.

4.

5.

Before installing thestarter, make sure

the

starter

mounting surfaces on the engine base are free of

dirt and oil to assure good electrical contact. Install the starter motor and tighten the mounting

bolts just enough to hold the starter in place. Remove the spark plugs from the engine to allow

free movement of the flywheel. Manually pull the starter pinion gear outward on

its shaft

so

that

its

teeth mesh fully with those on

the flywheel. Measure the amount of free travel (lash) between

the pinion gear teeth and the ring gear teeth, as shown in Figure52. Proper lash isO.O20+0.010 in. (0.51+_0.25 mm). Loosen and adjust the starter motor as necessary to obtain the correct setting.

6.

Torque down thestarter mounting bolts and reinstall the engine spark plugs.

FLYWHEEL

RING

GEAR

0.020

f

0.010''

(0.51

f

0.25

mm)

FLYWHEEL

GEAR FREE

TRAVEL

WHE

ENGAGED WITH

STARTER

G.EqR

STARTING

MOTOR

PINION

GEAR

FIGURE

50.

BATTERY

CONNECTIONS

38

FIGURE

52.

CHECKING STARTER GEAR LASH

Engine

Disassembly

DISASSEMBLY/ASSEMBLY

When complete engine disassembly is necessary, first remove all ComDleteassemblies. Individual assem-

1.

Use the proper bearing driver to install front main bearing after coating

it

with a light film of oil.

2.

Insert rear main bearing in rear bearing

plate.

blies

disassembled and repaired

at

another time.

as

“el

pump

and carburetor

can

be

3.

Insert crankshaft,rear bearing plate, and crank-

shaft gear.

Suggested Disassembly Order

1.

Drain crankcase.

2.

Disconnect all exhaust lines and electrical lines.

3.

Remove engine from its mountings and place

on

a suitable bench or work stand.

4.

Remove all housings, shrouds, blower housings, etc.

5.

Remove flywheel, using a puller.

6.

Remove the gear cover, being careiul to protect

7.

Remove the crank gear, using a gear puller and

8.

Remove all accessories such as oil filter, starter,

9.

Remove breaker point box.

the oil seal from keyway damage. ring. intake manifold, fuel lines, spark plugs, etc.

10. Remove oil base,

oil

pump and cylinder heads.

11. Remove valves, springs, lifters, etc.

12. Remove camshaft and gear assembly.

13.

Remove connecting rods and pistons.

14.

Remove rear bearing plate, crankshaft, and front bearing.

4.

Install piston and connecting rods.

5.

Install camshaft and gear assembly; align crank gear mark with cam gear mark.

6.

Install valve assemblies, oil pump, oil base, and cylinder heads.

7.

Install breaker point box.

8.

Install all accessories such as oil filter, starter,

9.

Install gear cover with oil seal and flywheel.

fuel lines and spark plugs.

10.

Set breaker points to obtain proper timing.

11.

Check valve clearance.

12. Install all housings and air cleaner.

13.

Fill crankcase with oil.

Operation

Start engine and check oil pressure. Run for approxi-

mately

15

minutes to bring engine to operating

temperature. Check for oil leaks, fuel leaks and exhaust

leaks. Adjust carburetor and governor for speed and

sensitivity.

Testing Compression

The compression tester is used

to

determine the

condition of valves, pistons, piston rings and cylinders. To check compression:

Keep all parts in their respective orders. Keep valve

assemblies together. Return rod caps to their respec-

tive

pistons. Analyze the reasons for parts failure.

1.

Run the engine until thoroughly warm.

2.

Stop engine and remove spark plugs.

Suggested Assembly Procedure

Engine assembly is normally the reverse of the disassembly procedure, observing proper clearances and torques. Use a torque wrench to assure proper

tightness. Coat the internal engine parts with oil as

they are assembled. After the internal engine parts are assembled, the engine should turn over by hand freely. Use only genuine Onan parts and special

tools

when reassembling your engine.

3.

Remove air cleaner and place throttle and choke in

4.

Insert the compression gauge in one spark plug

Refer to

SPEClFlCATlONS

SECTION

for compression pressures. There may be variations due to temperature, atmospheric conditions and altitude. These pressures are for a warm engine at cranking speed (about

300

the wide open position.

hole.

-.

rpm).

Tappet Adjustment

VALVE

SYSTEM

The engine is equipped with adjustablevalve tappets. The valve tappet clearance should be checked and

adjusted, if necessary, at least every

200

operating

hours or when poor engine performance is noticed.

Adjust the valve clearance only when engine is at

ambient temperature. Proceed as follows:

Aproperlyfunctioning valvesystem isessential forgood engine performance. AI1 engines utilize an L-head type valve design asshown in Figure

53.

Accessto thevalve system can beobtained by removing the cylinder heads and thevalvecoverson top

oftheengine.Avalvespring

'

comm-essor must be used to remove valves from the

1.

2.

3.

4.

5.

6.

7.

8.

Remove ignition key to prevent accidental star-

ting.

Remove all parts necessary to gain access to

valve tappets.

Remove spark plugs to ease the task of turning

the engine over by hand.

Place a socket wrench on the flywheel capscrew

and rotate the crankshaft in a clockwise direction

until

the left intake valve (viewed from flywheel end) opens and closes. Continue turning the crankshaft until the TC mark on the flywheel is lined up with theTC mark on the gear cover. This should place the left piston (#1) at the top of its compression stroke. Verify that the left intake and exhaust valves are closed and there is no pressure on the valve lifters.

The correct feeler gauge for the valve adjustment

(SPECIFICATIONS)

should pass freely between

valve stem and tappet; a

0.002

inch

(0.05

mm)

thicker gauge should not (Figure

53).

To

correct the valve cleara'nce, use a 7/16-inch open end wrench to turn the adjusting screw to obtain the correct clearance. The screw is selflocking and will stay where

it

is set. A 9/16-inch

(14 mm) open end wrench is required to hold the

tappet while turning the adjusting screw.

To adjust valves on the right hand cylinder, turn

engine one complete revolution and again line up mark on the flywheel and theTC markon thegear

cover. Then follow adjustment procedure given for left hand cylinder.

Replace all parts removed in Step

2.

Tighten all

screws securely. Torque manifold bolts

to

spec-

ified torque.

..

NOTE

cylinder block.

A valve stem seal

is

used on the intake valve guides of some engines. This seal must be replaced each time the valve

is

removed.

Placevalves, springs, retainers, and tappets in a rack as

they are removed from cylinder block

so

they can

be

identified and reinstalled in their original locations.

Discard old valve stem seals and replace with new ones

during assembly.

Use the following procedures to inspect and service the

valve system.

I

Inspection

Clean carbon from the valves, valve seats, valve guides, and cylinder block.

Valves:

Check the valve face for evidence of burning,

warpage, out-of-round, and carbon deposits.

Burning and pitting are caused by the valve failing to

seat tightly. This condition is often caused by hard

carbon particles on the seat.

It

may also be due

to

weak valve springs, insufficient tappet clearance, warpage, and misalignment.

VALVE

RETAINER>

\(

~~

VALVE

SPRING,

*:*w

'E

CI

XARANCE

USEASTANDARD

AU

WRENCH

TO

ADJUST

THE

TAI

VALVE

ADJUSTING

TOMOTIVE

TY

PE

VALVE

CLEARANCE

7

/

SCREW

N

'PETS.

H

.I

''

1

ONLY)

SEAL

I

VT-1005

FIGURE

53.

VALVE ASSEMBLY

40

1

Warpage occurs chiefly in the upper stem due to its exposure to intense heat. Out-of-round wear follows when the seat is pounded by a valve whose head is

not in line with the stem and guide. If

a

valve face is

burned or warped, or

if

the stem is worn, install a new

valve.

Too

much clearance in the intake guide admits air and oil into the combustion chamber, upsetting carburetion, increasing oil consumption, and making heavy carbon deposits. Carbon reduces heat dissipation. Clean metal is a good heat conductor' but carbon insulates and retains heat. This increases combustion chamber temperatures which causes warping and burning.

Unburned carbon residue gums valve stems and causes them to stick in the guide. Deposits of hard carbon with sharp points projecting become white hot and cause pre-ignition and pinging.

Refinish valves that are slightly pitted or burned on an

accurate valve grinder. If valves are badly pitted or have a thin margin when refacing, replace them.

VT-1020

FIGURE

54.

VALVE STEM AND VALVE GUIDE INSPECTION

Sfems And Guides:

Always check valve stems and

guides for wear (Figure

54).

Use a hole gauge to

measure the valve guide. When clearance with stem exceeds that specified in

DIMENSIONS AND CLEAR-

ANCES,

replace either valve or guide or both,

as

may be

necessary. Always regrind seatto make concentric with

the newly installed guide.

Worn valve stem guides can be replaced from inside the valve chamber (a seal is provided behind the

intake valve guides only). The smaller diameter of the tapered valve guides must face toward the valve head. Tappets are also replaceable from the valve chamber after first removing the valve assemblies.

Valve Guide Removal:

Before removing valve guides,

use

an electric drill with a wire brush

to

remove carbon and otherforeign material from top surfaceof guides. Failure to perform this operation may result in damage

to

the guide bores. Drive the guides out with

a

hammer and valve guide driver.

Driving

out

old guides can damage

fhe tappet bores. Be careful not

to

sfrike bores

wifh

driver.

Valve Guide lnsfallafionr

Run a small polishing rod covered with crocus cloth through valve guide holes to clean out carbon and otherforeign materials. Place a new gasket on the intake valve guide, and coat the

outer edge of each new guide with oil. Place guide, notch-up, in cylinder block and press in until guide stops or protrudes

11/32

inch

(8.7

mm) from rocker boxside of block. Asuggested method of installation is shown in Figure

55.

ROD

'

NUT

5/16-18

HEX.

NUT

\

(2

REQUIRED)

5/16

FLAT

WASHER

(2

REQUIRED)

-18

THREADED ROD

(Elm)

T-

5/8"

(16

mm)

vr-1023

FIGURE

55.

VALVE GUIDE INSTALLATION

Valve Stem Seals:

Do

not reuse valve stem seals. Each

time the valves are removed from cylinder block, a

new seal must be used when valve is reinstalled.

Do

not

remove valve after seal

is

insfalled. Valve can be wifhdrawn only as far as the groove in valve stem. Do not allow valve stem seal

fo

come in confacf

wifh

groove orseal

damage will result.

41

Valve

Spring:

Check valve springs for cracks, worn ends, distortion, and tension. If spring ends are worn, check valvespring retainer forwear. Check

for

spring distortion by placing spring on aflat surface next to a square. Measure height of spring and rotate

it

against square edge to measure distortion. If distortion exceeds

0.06

inch

(1.5

mm) replace spring. Check spring tension at the installed height for both the valve open and closed position using an accurate valve spring tester. Replace any valve spring that is weak, cracked, worn, or distorted.

Valve

Rofafors:

Positive type valve rotators prolong valve life and decrease valve repairs. When functioning properly, the valve is rotated

a

fraction of a turn each time it opens. While at open position, the valve must rotate freely. There

is

no easy way to

determine if a valve rotator is good or bad. Onan

recommends that valve rotators be replaced at each major overhaul or if a build-up of carbon is noted

on

valve face and valve seat.

Valve Seafs:

Inspect valve seat inserts. If seats are loose, cracked or severely pitted, new ones must be installed. Removevalve seat inserts using avalve seat removal tool. If valve seat insert bores in cylinder block are damaged or worn

so

that a press fit cannot

be obtained when installing new standard size valve

seat inserts, the bores must be machined for an oversize seat.

USE

NEW

VALVE

SEAT

TO

ADJUST

PULLER

DEPTH

PULLER

JAWS

C-1104

FIGURE

56.

VALVE

SEAT

REMOVAL

Valve Seaf Removal:

Remove carbon and combustion deposits from valve seat. Select proper puller size determined by inside diameter of valve seat. On some pullers use a new seat as a guide to adjust puller

depth (Figure

56).

Puller jaws must expand into

cylinder block at the point where bottom of valve seat

insert rests

on

cylinder block (Figure

56).

Position puller on valve seat and tighten hex nut. Clamp cylinder block to a solid bench. Attach slide hammer to puller.Tighten hex nut between each blowwith the slide hammer

A

USE

PROPER

TOOL

CHECK

THIS

SURFACE

FOR BURRS BEFORE

SERTING

SEAT

FIGURE

57.

INSERTING

NEW

VALVE

SEAT

Valve Seaf lnsfallafion:

After the old seat has been

removed, clean out any carbon or metal burrs from the

seat

insert

recess.

Use a valve

seat

insert driver and

hammer to install the insert (Figure

57).

Drive the valve

seat insert in

so

that insert enters the recess evenly.

Make certain that the valve seat insert rests solidly on

the bottom of the recess all the way around its

circumference (Figure

57).

t

To

assure a tight valve seat fit and eliminate the danger

of seat loosening in the bore, valveseat must be staked.

insert valve seat staker into valve seat or guide in cylinder

block.

Using

a

lead hammer,

strike

the

staking

tool a sharp

blow

to wedge new valve securely in place.

It

will

be

necessary to refinish valve seat inserts before

installing valves.

42

TAPPETS

Very little wear takes place on tappet diameters or in tappet bores. If the clearance between tappet and

bore in cylinder

blockexceedsspecifications,

replace

the tappet.

Inspect the tappet faces which contact camshaft lobes for roughness, scuffing, or concave wear. Replace any worn tappets. If tappets are worn, inspect camshaft for wear.

VALVE FACE AND SEAT GRINDING

Some engines are equipped with a premium valve package (aluminized intakevalves). If thealuminized valve face does not clean-up using a wire brush, the valve face may be refinished. This removes the aluminized coating from thevalve face. An aluminized valve that has been refinished will normally have a life expectancy equal to a standard valve. If longer valve life is required, worn or damaged valves should be replaced with new premium valves.

Before installing new valves or previously used valves, inspect valve seats for proper valve seating.

If

used valves are reinstalled, the valve stems should be cleaned and valve faces ground to their specified

angles of 44'. Refinish valve seats to a

45'

angle. When refacing valves and seats, remove all evidence of pitting and grooving. If end of valve stem is pitted or worn, true it and clean

it

up on the refacer wheel. A

very light grind is usually enough to square stem and

remove any pits or burrs. The valve guide should be thoroughly cleaned. If valve guide is worn, or valve is warped, the necessary parts must be replaced.

By grinding the valve face and seat at slightly different angles, a fine line of contact on face and seat is obtained, eliminating the need to lap the seating surfaces. The one degree difference in angles is defined as the interference angle (Figure

58).

The

,

seat angle is greater than that

of

the valve face. This assures contact at the maximum diameter on valve seat seating surface.

'

FIGURE

58.

VALVE INTERFERENCE ANGLE

VT-1021

43

Refinish valve faces to a44' angle on avalve refacing machine. The first cut from valve face must be

a

light grinding. Check if there is an unevenness of metal being removed. If

only

a

part of the valve face has been touched, check to see if valve is properlyseated in machine or if valve is warped, worn, or distorted.

When cut

is

even around the whole valve face, keep grinding until complete face is ground clean. Be sure the correct valve face angle is maintained. When valve head is warped,

a

knife edge will be ground

(Figure

59)

on part or all of the head due to the large amount of metal that must be completely removed to reface valve. Heavy valve heads are required for strength and good heat dissipation. Knife edges lead to breakage, burning, and pre-ignition due to heat localizing on the edge.

Replace any valve that cannot be entirely refaced

while keeping agood valve margin (Figure

59)

orthat

is warped, worn, or damaged in any way.The amount

of grinding necessary to true avalve indicateswhether valve head is worn or warped.

WARPED

VALVE WITH

KNIFE EDGE KNIFE EDGE

GOODMARGIN

I

\

i

f

IT

1/16

INCH

I

(1.6mm)

MINIMUM

1-1164

FIGURE

59.

VALVE HEAD MARGIN

When new valve seats are installed, or previously

used seats reground, refinishing must be done with a valve seat grinder used according to the manufacturer's directions.

Valve seats should be ground with a

45

degree stone and the width of the seat band should be 1/32 inch to 3/64 inch

(0.79

to

1.2

mm) wide. Grind only enough

to assure proper seating.

Place each valve in its proper location. Check each valve for a tight seat. Make several marks at regular intervals across the valve face using machinist's bluing. Observe if the marks rub

off

uniformly when thevalve is rotated part of aturn againsttheseat.The valve seat should contact the valve face evenly at all

points. The line

of

contact should be

at

the center

of

the valve face.

FLYWHEEL

Removing the flywheel is a relatively simple process,

but the following procedure must be followed to avoid damage to the gear case and possible injury to the operator.

1.

2.

3.

Turn the flywheel mounting screw outward about two turns.

-1

Do

not remove the screw com-

pletely since it acts as a re-

strainer when the flywheel snaps loose. If the

flywheel is not held by the screw, the spring action in the wheel will cause if to fly off with great force which can cause injury to the opera tor.

Install a puller on the flywheel.

Turn the puller capscrews in alternately, until the wheel snaps loose

on

the shaft.

Do

not use a screwdriver orsim-

ilar fool or pry behind the

flywheel against the gear case. The gear case

cover

is

die-cast material and will break if undue

pressure is applied in this manner.

4.

Unscrew the pullerfrom the flywheel, removethe flywheel mounting screw and washer, and pull the flywheel off the shaft. Take care not to drop the wheel. A bent or broken fin will destroy the

balance. Always use a steel key for mounting the flywheel.

GEAR

COVER

After removing the mounting screws, tap the gear cover gently with a soft faced hammer to loosen

it

(Figure

60).

Make certain flywheel key is removed from crankshaft before removing gear cover.

1

When installing the gear cover, make sure that the pin

in the gear cover engages the nylon lined (smooth) hole in the governor cup. Turn the governor cup

so

that the nylon lined hole is at the three o’clock position. Useasmall amount of greasetoassist in holding governor cup in position. The smooth side of the governor yoke must ride against the governor cup.

Turn the governor arm and shaft clockwise as far as

possible and hold in this position until the gear cover is installed flush against the crankcase. Be careful not

to damage the gear cover oil seal.

GOVERNORCUP GOVERNOR ARM

OVERNOR SHP

F

OTATE

COVE RNOR

CUP

FITS INTO THE SHAFT YOKE

METAL LINED

HOLE OR

PLASTIC

BUSHING IN THE

CUP

SO

TF..4T

ROLL PIN‘

GOVERN0

R

A35Va.

,GOVERNOR CUP

\=

IFT

IF

FEELER

WILL

ENTER HOLE

I/z”

BALL HAS

FALLEN

OUT

FIGURE

60.

GEAR

COVER

ASSEMBLY

44

4

WHEN GOVERNOR

IS

PROPERLY

ASSEMBLED

THE

DIMENSION

SHOWN

ON

DRAWING

WILL

BE

AS

INDICATED

CENTER

,

RIGHT

WRONG

INSTALLATION

OF

BALL

SPACER

G1107

5

BALL

GOVERNOR

6

BALL

GOVERNOR

8

BALL

GOVERNOR

SI238

FLYBALL LOCATIONS

FIGURE

61.

GOVERNOR

CUP

DETAILS

GOVERNOR

CUP

With the gear cover removed, the governor cup can be taken

off

after removing the snap ring from the camshaft

center pin. Catch the flyballs while sliding the cup

off

(Figure 61). Replace with a new part any flyball which is grooved or

has a flat spot; the ball spacer if its arms are worn or otherwise damaged; the gearispacer assembly if loose on gear hub, and the governor cup if the race surface is grooved or rough. The governor cup must be

a

freespinning fit on the camshaft center pin, but without any excessive play.

If replacing the ball spacer, be sure to position

it

so

an

arm

is

lined up with the space on the camshaft gear (if

your camshaft gear does not have a space in it,

disregard this paragraph). If the ball spacer arm is not lined up with the space in the camshaft gear,

a

flyball can slip into the space and cause engine racing and governing problems (Figure

61).

When installing the governor cup, tilt the engine

so

the

gear is up, put the flyballs in place (Figure61), and

install the cup and snap ring on the center pin.

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) for the governor cup, as illustrated. Hold the cup against the flyballs when measuring. The camshaft 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 distance is less than 7/32“

(5.6 mrn), (the engine will race, especially at no load) remove the center pin and press in a new pin.

TIMING

GEARS

If replacement of either the crankshaft gear or the camshaft gear becomes necessary, always install both gears new.

The camshaft and gear must be replaced as an assembly. Before removing the camshaft and gear assembly, remove the cylinder head and valve assemblies. Then remove the operating plunger for the breaker points and

tappets.

To

remove the crankshaft gear, first remove the snap ring and retainer washer, then attach the gear pulling ring using

two

No.

10-32 screws (Figure 62). Tighten the screws alternately until both are tight. Attach a gear puller to the puller ring and proceed to remove the gear.

Each timing gear is stamped with

“0

near the edge. The

gear teeth must mesh

so

that these marks exactly coincide when the gears are installed in the engine. When installing the camshaft gear and shaft assembly, be sure that the thrust washer

is

properly in place behind the camshaft gear. Then install the crankshaft retaining washer and lock ring.

45

HESE MARKS MUST

ALIGN WHEN INSTALLING TIMING GEARS.

FIGURE

62.

TIMING GEAR REMOVAL AND INSTALLATION

PISTONS

AND

CONNECTING

RODS

Observe the following procedure when removing pistons and connecting rods from the engine.

1.

2.

3.

Drain oil. Remove the cylinder head and oil base pan from the

engine.

Remove carbon from top of cylinder boreand check

for a ridge. Remove ridge (Figure 63) with a ridge

reamer before attempting piston removal.

ACAUT~ON

Using a ridge reamer

to

remove

carbon can cause damage

to

cylinder bore.

5.

push the rod and piston assembly out through the top of the cylinder, using a hammer handle. Avoid scratching the crankpin and cylinder wall when

removing the piston and rod. Mark each piston and rod assembly

so

they can be

returned to their respective cylinders after overhaul.

Keep connecting rod beairng caps with their respective rods.

Remove the piston rings from the piston with a piston ring spreader asshown in Figure64. Remove

the piston pin retainer and push the piston pin out.

4.

FIGURE

63.

REMOVING RIDGE FROM CYLINDER

Forcing fhe pisfon from fhe cylinder before reaming may

cause damage

to

fhe piston lands and break

rings.

Turn the crankshaft until the piston is at the bottom

of

its stroke, and remove the connecting rod

nuts. Lift the rod bearing cap from the rod, and

I

i

\

/

FIGURE

64.

REMOVING PISTON RINGS

a

46

Remove dirt and deposits from the piston surfaces

with an approved cleaning solvent. Clean the piston

ring grooves with a groove cleaner or the end

of

a

piston ring filed to a sharp point (Figure

65).

Care

must be taken not

to

remove metal from the groove

sides or bottom.

Do

not use a caustic cleaning sol-

-

venf or wire brush for cleaning

pisfons. These materials will cause pisfon damage.

FIGURE

65.

PISTON GROOVE CLEANING

When cleaning the connecting rods in solvent, in-

clude the rod bore. Blow out all passages with compressed air.

Engines that have been fitted with

0.005

inch

(0.13

mm) oversize pistons at the factory are identified by

the letter

E

after the serial number. Number is stamped on the cylinder block and on the unit nameplate.

Inspection

The following text contains inspection procedures concerning pistons and connecting rods.

Piston Inspection:

1.

Inspect the pistons for fractures at the ring lands, skirts, and pin bosses. Check for wear at the ring lands, using a new ring and feeler gauge as shown in Figure

66.

Replace the piston when the

side clearance of the top compression ring

reaches

0.008

inch

(0.20

rnm).

FIGURE

66.

CHECKING RING SIDE CLEARANCE

2.

Replace pistons showing signs of scuffing, scoring, worn ring lands, fractures, or damage from preignition. Excessive piston wear near the edge

of

the

top ring land indicates pre-ignition.

3.

Proper piston tolerances must be maintained for satisfactory operation.

4.

Refer

to

DIMENSIONS AND CLEARANCES

to

determine where

to

measure piston to be sure the

total clearance follows specifications.

.

0000

01

MEASURE CLEARANCE

HERE

+:

FIGURE

67.

MEASURING PISTON CLEARANCE

Connecfing

Rod

Inspection:

1.

Replace connecting rod boltsand nuts with darnaged threads. Replace connecting rods with deep nicks, signs of fractures, scored bores or bores out of round more than

0.002

inch.

2.

Use a new piston pin to check connecting rod for wear.

A

push-fit clearance is required and varies from engine to engine. If a new piston pin falls through a dry rod pin bore as a, result of its own weight, replace the rod.

47

Pisfon Rings:

1. Install the piston ring in the cylinder bore. Invert the piston and push the ring to the end of ring travel, about halfway into the bore. This trues the

ring end gap. Check the gap with a feeler gauge

(Figure

68).

2.

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 isO.001 inch

(0.03

mm) undersizewill reduce

the end gap

0.003

inch

(0.08

mm).

FIGURE

68.

POSITIONING

OF

PISTON RING

AND MEASURING

OF

END GAP

CYLINDER

BLOCK

The cylinder block is the main support for all other

basic engine parts. Crankshaft and camshaft are

supported by the block, assuring alignment

of

the

crankshaft and cylinder bores.

Cleaning

After removing pistons, crankshaft, cylinder heads, etc., inspect block for cracks and extreme wear. If

block is still serviceable, prepare

it

for cleaning as

follows:

1.

Scrapeall old gasket material from block. Remove oil by-pass to allow cleaning solution to contact inside of oil passages.

2.

Remove grease and scale from cylinder block by agitating in a bath of commercial cleaning solution or hot soapy washing solution.

3.

Rinse block in clean hot waterto removecleaning solution.

1

Inspection

When rebuilding theengine, thoroughly inspect block

for any condition that would make it unfit for further use. This inspection must be made after all parts have been removed and block has been thoroughly cleaned and dried.

1.

Make a thorough check for cracks. Minute cracks may be detected by coating the suspected area

with a mixture of

25

percent kerosene and

75

percent light motor oil. Wipe the part dry and immediately apply a coating of zinc oxide (white lead) dissolved in wood alcohol. If cracks are

present, the whitecoating will become discolored at the defective area. Always replace a cracked cylinder block.

2.

Inspect all machined surfaces and threaded holes. Carefully remove any nicks or burrs from machined surfaces. Clean out tapped holes and clean up any damaged threads.

3.

Check top of block for flatness with a straight edge and a feeler gauge.

Cyjinder Bore

Inspection:

Inspect cylinder bores for scuffing, scratches, wear, and scoring. If cylinder bores are scuffed, scratched, scored, or worn, they must be rebored and honed for the next oversize piston.

When the appearance of cylinder bores is good and there are no scuff marks, check cylinder bore for wear

or out of roundess as follows:

1.

Check cylinder bore for taper, out of round, and wearwith a cylinder bore gauge, telescope gauge or inside micrometer. These measuremets should

be taken at four places, top and bottom

of

piston

ring travel, parallel and perpendicular

to

axis of

crankshaft.

2.

Record measurements taken at top and bottom

of

piston travel as follows (Figure

69):

48

.

A. Measure and record as

“A’

the cylinder bore

diameter (parallel to crankshaft) near the top

of cylinder bore where greatest amount of

wear occurs.

B.

Also

measure and record as“B” cylinder bore diameter (parallel to crankshaft) at the bottom of piston travel.

C.

Measure and record as

“C”

cylinder bore diameter (perpendicular to crankshaft) near the top of cylinder bore where greatest amount of wear occurs.

D. Also measure and record as“D”cy1inder bore

diameter (perpendicular to crankshaft) at the bottom of piston travel.

E.

Reading

“A’

subtracted from reading

“B

and

reading

“c”

subtracted from reading

“D

indi-

cates cylinder taper. If cylinder taper exceeds that specified

in

DlMENSlONS

AND

CLEARANCES,

rebore and

hone cylinder to the next oversize.

F.

Reading

“A”

compared

to

reading

“C”

and

reading

“B

compared to reading

“D’

indicate whether or not cylinder is out of round. If out of round exceeds that specified in

DIMENSIONS

AND CLEARANCES,

the cylinders must be

rebored and honed to the next oversize.

A

reboring machine is used when going to oversize pistons.

Reboring

the

Cylinder

Rebore and hone engine whenever cylinder bore is worn, damaged, out of round, or if cylinder taper exceeds specifications.

A

worn cylinder bore should be resized to the smallest standard oversize diameter at which it will clean up. The final finish and bore diameters should then be obtained by honing.

E%{

AREA

TOP END

OF

CYLINDER

RING

.WEAR

AREA

BOTTOM

OF-RING

TRAVEL

c

1090

FIGURE

69.

METHODS

OF

MEASURING THE DIAMETER

OF

A

CYLINDER

BORE

If

boring bar

is

operatedincorrecfly,

if will produce

a

rough cylinder

sur-

face that may not clean up even when honed. Boring

should be done only

by

qualified service personnel

who

are careful in their

work.

After boring to the correct oversize cylinder bore dimension piston and ring clearance should be appropriate. There is no need to adjust or “fit” pistons

and rings. When reboring cylinders, take the following pre-

cautions:

1.

Make sure cutting tool is properly ground before

2.

Besure top of engine block is smooth and deposit

using it.

free.

49

3.

Clean base of boring bar before bar is set up. Deposits under boring bar will cause

it

to

tilt,

and

the cylinder will be distorted after boring.

4.

Makean initial rough cut, followed byafinish cut.

Then hone cylinder bore to the specified oversize.

Honing Cylinders (Using Precision Hones)

Refer to hone manufacturer’s recommended grit size to produce specified surface finish

of

20 to

40

RMS.

Too rough

of

a finish will wear out the rings and too

smooth of a finish can retard piston ring seating.

1.

Position block solidly for either vertical or horizontal honing. Use either a drill press or heavyduty drill which operates at approximately 250 to

450 rpm.

2. Follow hone manufacturer’s instructions for the use of oil or lubricant on stones. Do not use lubri-

cants with a dry hone.

3.

Insert hone in boreand adjust stonestofitsnugly

to the narrowest section. When adjusted cor-

rectly, the hone should not shake or chatter in

cylinder bore, but will drag freely up and down when hone is not running.

4. Connect drill to hone and start drill. Feel out bore for high spots, which cause an increased drag on stones. Move hone up and down in bore with short overlapping strokes about

40

times per

minute. Usually bottom of cylinder must be

worked out first because

it

is smaller.

As

cylinder takes a uniform diameter, move hone up and down all the way through cylinder bore.

5.

Check diameter of the cylinder regularly during honing.

A

dial bore gauge is the easiest method,

but

a

telescoping gauge can be used. Check size

at six places in bore; measure twiceat top, middle

and bottom at SO-degree angles.

6.

Crosshatch formed by the stones should form an included angle of 23 degrees. This can be achieved by moving the rotating hone (250 to450 rpm) up and down in cylinder bore about 40 times per minute.

7.

Clean cylinder bores thoroughly with soap, water, and clean rags.

A

clean white rag should not

become soiled on wall after cleaning is complete.

Do

not use a solvent or gasoline, since they wash

oil from the walls but leave metal particles.

8.

Dry crankcase and coat

it

with oil.

Deglazing Cylinder Bores

Deglaze the cylinder bores if there are no scuff marks and no wear or out

of

round beyond specifications

before installing new rings. Deglazing gives a fine

finish but does not enlarge cylinder diameter,

so

the

original pistons with new rings may still be used.

The reason for deglazing a cylinder is to provide

cavities to hold oil during piston ring break-in.

1.

Wipe cylinder bores with a clean cloth which has

been dipped in clean, light engine oil.

6

2.

Use

a brush type deglazing tool with coated bristle tips to produce a crosshatch pattern in the cylinder bore.

3. The deglazing tool should be driven by a slow speed drill. Move deglazing tool up and down in cylinder

(10

to

12 complete strokes) rapidly enough to obtain a crosshatch pattern as shown in Figure

70.

PRODUCE

CROSS

HATCH

SCRATCHES

FOR

FAST

RING

SEATING

AVOIDTHIS

FINISH

01091

FIGURE

70.

CROSS

HATCHING

Never use gasoline or commercial cleaners to clean cylinder

bores after deglazing

or

honing. These solvents

will not remove abrasives from

the

walls.

Abra-

sives not removed from engine will rapidly wear rings, cylinder walls, and bearing surfaces of all lubricated

parts,

4. Clean cylinder bore thoroughly with soap, water, and clean rags. Continue cleaning until a clean white rag shows no discoloring when wiped through cylinder bore.

50

CRANKSHAFT

Inspect the bearing journals.

If

they are scored and cannot be smoothed out by dressing down, the bearing journals should be refinished to use nearest avail-

able undersize bearings or a new crankshaft should

be installed. If a worn main bearing journal cannot be

fitted with an available precision type undersize bearing, then refinish

it

to the next undersize. If a worn rod journal cannot be fitted by installing new bearing inserts (forged rod), then refinish

it

to take the next

corresponding undersize bearing insert available.

Whenever making major repairs on the engine, always

inspect the drilled passages of the crankshaft. Clean

them to remove any foreign material and to assure

proper lubrication of the connecting rods.

Shot Peening:

On older model engines, shot peening is required to prevent failures. When the shaft is machined, followthedatatoshot peen each crankpin

fillet.

1. Almen gauge reading: 0.01 2A

2.

Mask off connecting rod bearing areas.

3.

Peen with 0.019 inch (0.49 mm) diameter cast

steel shot.

4.

Peen for

30

seconds on each crankpin fillet.

Undersize bearings and connecting rods are available to rework the shaft to 0.010,0.020, and

0.030

inch

undersize.

BEARINGS

With camshaft and crankshaftremoved, usea micrometer to measure diameter of bearing journals. Use a dial bore gauge or a telescopic gauge and micrometer to measure inside diameter of bearings. Refer to

Dimen-

sion

and

Clearance Section

to determine if clearances

are within specifications.

Any bearing that is scored, chipped, pitted beyond the specified limits must be replaced.

or worn

7/32"

(5.6

mrn)

FROM

OUTSIDE

ALIGN HOLE IN

BEARING

------------

WITH

HOLE

'

IN

BEARING

BORE

CAPSHAFT BEARING

FIGURE

71.

FRONT

CAMSHAFT

BEARING

Removal of the camshaft bearings requires complete disassembly of the engine. Use a press or a suitaliie driver to remove bearings. Support casting to avoid distortion and to avoid damaging the bearing bore during removal and installation.

Replacement camshaft bearings are precision type which do not require line reaming or line boring after installation. Clean outside

of

the bearing and bearing bore in the block. Before installing cam bearings use Locktite Bearing Mount

on

outside diameter of bearing. Use a combination bearing driver to install bearings. Place the bearing

on

the crankcase over the bearing bore with the lubricating hole (front only) in the proper position. Be sure to start the bearing straight. Press in the front bearing flush with the outside end of the bearing bore. Front cam bearing oil hole must line up with oiling hole in cyliner block (Figure 71). Press in the rear camshaft bearing until past the ignition plunger hole.

Lubricate bearing surfaces with oil after installing.

New crankshaft main bearings are precision type which

do

not

require line reaming or line boring after installa-

tion. Use a press or asuitable driver to remove bearings.

Support casting to avoid distortion and to avoid damaging the bearing bore during removal and installation.

Before installing main bearings, expand bearing bore by placing the casting in an oven heated to

2OOOF

(94°C).

If

practical, cool the precision bearing to shrink

it.

..

Before installing the front main bearing, use the towelette included with the bearing kit to clean the outside of the bearing and bearing bore in the block.

-1

Breathing vapor from towelette and

prolonged

contact

with skin can

be

harmful. Be sure area is well ventilated.

51

After allowing three to four minutes for drying, apply the Locktite from the small tube to the mating surfaces of the bearing and the bearing bore. Align the oil holes in the bearing with the oil holes in the bearing bore (Fig-

ure

73).

The oil passage should be at least half open. Install the bearing flush with the block, using the combination driver. Wipe

off

any exesss Locktite around the

bearing.

Allow

at least one hour for hardening at room

tern peratu re.

REAR BEARING END PLATE

ALIGN BEARING OIL HOLES

WITH OIL HOLES IN

BEARING BORE

THRUST

WASHER

FIGURE

72.

BEARINGS FOR REAR BEARING

PLATE

Engines shipped from the factory have separate thrust washers and main bearings for both front and rear of engine. Front bearing replacement part is a one piece bearing (with attached thrust washer) as shown in Figure

73.

Do

not add an additional thrust washer to this

front bearing.

FRONT MAIN

BEARING BORE

c

ALIGN BEARING

NOTCHES

W

lTli

LOCK

PINS

AND MATCH

OIL

HOLES

849

Rev

REPLACEMENT

FRONT MAIN

BEARING

FIGURE

73.

FRONT

BEARING

INSTALLATION

In the rear bearing plate, install the bearing flush

to

1

164

inch

(0.40

mm) below the end of the bore. Be sure

to align the oil holes in the bearing with the oil holes in

the bearing bore (Figure

72).

The oil passage must be at

least half open. Lubricate bearing after installation.

If

head of lock pin is damaged, use side cutters or Easy Out tool to remove and install new pin. Oil grooves in thrust washers must face the cranksahft, and washers must be flat (not bent). The two notches on each washer must fit over the two lock pins to prevent riding on the crankshaft (Figure

72).

Lubricate the front main bearing lightly with

oil

and insert the Crankshaft. With the raar bearing plate gasket in place and the rear plate bearing lubricated, slide the thrust washer (grooves toward crankshaft and plate over the end of the crankshaft. Line up notches of thrust washer with lock pins before tightening end plate or lock pins will be damaged.

A light film

of

oil

on the thrust washer may

hold

it in place while

installing the crankshaft.

&

CRANKSHAFT

ENDPLAY

After the rear bearing end plate has been tightened,

using the torque recommended in

Assembly

Torques

and Special

Tools,

check the crankshaft endplay as

shown in Figure

74.

If there istoo much endplay (see

Dimensions and Clearances

for

minimum and max-

imum endplay), remove the rear bearing end plate

and add ashim (Figure

72)

between thethrustwasher and plate. Reinstall the end plate, making sure the thrust washer and shim notches line up with the lock pins. Torque and recheck endplay

of

the crankshaft.

MEASURE ENDPLAY

HERE

J

(REFER

TO

DIMENSIONS

AND CLEARANCES)

FIGURE

74.

CRANKSHAFT ENDPLAY

,

52

REAR

BEARING PLATE

THIS SURFACE SHOULD BE

CLEANED

OF

ALL OLD SEALING COMPOUND BEFORE INSTALLING

SEAL

\

DRIVE

OR

PRESS

OIL

SEAL TO SHOULDER

OF

THE PLATE

BORE

MOUNTING FACE

/

OF

GEAR COVER

THIS

GEAR COVER SURFACE SHOULD BE CLEANED OF ALL OLD SEALING COMPOUND BEFORE INSTALLING SEAL

GEAR

COVER OIL SEAL

REAR

BEARING PLATE

OIL SEAL

IS-1163

FIGURE

75.

GEAR COVER AND REAR BEARING

PLATE

OIL SEALS

The bearing plate must be removed to replace the oil

seal (Figure

75).

Drive the oil seal out from the inside.

3.

Install the rings on the pistonsstarting with theoil

control ring (Figure

76).

Usea piston ring spreader

to prevent twisting or excessive expansion

of

the

ring. Compression rings have a dot or the word “top” on one side of the ring to indicate which side faces the top of the piston. Unmarked piston

rings can be installed either way. The oil control

rinn has an expander; install the expander first

Before installing seals, fill the space between lips with a multi-purpose grease. This will improve sealing.

and then close‘until the expander ends butt. The joint should be

180

degrees from the gap

of

that

ring.

When installing the gear cover oil seal, tap the seal inward until itis.645 inch (16.4 mm)from thefrontofthe gear cover.

When installing the bearing plate oil seal, tap the seal into the bearing plate bore to bottom against the shoulder in the plate bore. Use a seal expander or place

a

piece of heavy paper around the end of the crankshaft, when replacing the bearing plateto avoid damaging the seal. Remove the paper as soon as the plate is in place.

Engines equipped with some types of reduction gear

assemblies do not use the rear oil seal. The reduction gear assembly is oiled directly from the engine crankcase. Refer to the instructions screened on the case of the reduction gear assembly.

PISTON

ASSEMBLY

1.

Lubricate all parts with engine oil.

2.

Position piston on its respective rod and install

the pin.

HEAVIEST

COMPRESSION

RING

IN

TOP.

GROOVE

COMPRESSION

RINGS

OIL

CONTROL

RING

FIGURE

76.

PISTON RINGS

53

INSTALLATION

OF

PISTON

IN

CYLINDER

1.

Turn the crankshaft to position the number one

rod bearing journal at the bottom of its stroke.

2.

Lubricate the number one piston assembly and the inside of the cylinder. Compress the rings with a ring compressor as shown in Figure 77.

3.

Position the piston and rod assembly in the cylinder block. Oil hole in connecting rod must face camshaft. Rod bolts must be

off-set

toward outside of block.

4.

Tap the piston down into the bore with the handle end of a hammer until the connecting rod is seated on the journal (Figure 77). Install the bearing cap on the rod. Install and tighten the bolts evenly, in steps, to the specified torques.

The bearing cap must be tapped to align

it

properly with the rest of the connecting rod. Clearance varies on the journal if this is not done.

5.

Install the remaining piston and rod in the same manner. Crank the engine over by hand to see

that all bearings are free.

4

6.

Install oil pump pick up tube and cap.

7.

Install the oil base with a new gasket.

8.

Install the cylinder heads. See Cylinder Headsec-

tion for torques and torquing procedure.

9.

Replace oil and break in engine.

OIL

HOLE

cl-1077

FIGURE

77.

INSTALLING PISTON AND CONNECTING ROD

54

I

CYLINDER

HEAD

GASKET

REPLACEMENT

Remove the cylinder heads for lead cleaning and gasket change at least every200 hours, or when poor

engine performance

is

noticed. For engines running

on unleaded fuel this interval may be extended to400

hours.

1.

2.

3.

4.

5.

6.

Use a 1/2 inch

(13

mm) socket wrench

to

remove

cylinder head bolts. Lift heads

off.

Do

not torque or remove heads

@%!!@I

when they are hot. Warpage

may occur.The gasket surface must be below

100"

F

before removal. At temperatures above

100°F,

the gasket will become gummy and diffi-

cult to remove from the surface

of

the blockand

cylinder head.

After removing heads, clean out all carbon deposits. Be careful not to damage the outer sealing edges where gaskets fit. The heads are made of aluminum and can be damaged by careless handling.

Use new head gaskets, and clean both the heads and the cylinder block thoroughlywhere the head gaskets rest.

Place a head gasket on the cylinder head, and align the stud holes in

the

gasket with the stud holes in the cylinder head. While holding the gasket against the cylinder head, carefully install

the cylinder head on the engine.

Do

not attempt to slide the gasket over the studs without the cylinder head behind

it

or the gasket may tear.

Some engines have two compression washers and one hardened washer on the long cylinder head studs (top

6

studs on each side) as shown in

Figure

78.

When these washers are used, they must be installed as shown. When properly installed, only the outside edges of the compression washers

will

be in contact with each other. Install a flat washer and nut on each of the four bottom studs.

Follow the head torque sequence shown in Figure

79. A.

Asbestos head gasket torque procedure: Tighten all nuts to 5 ft-lbs

(7

Nm), then

10

ft-lb

(14

Nm), then to the torque specified in the

ASSEMBLY

TORQUES

section. Recheck all

nuts for correct torque.

-1

Asbestos gaskets contain fibers that when airborne

can be harmful to your health. Use a respi-

rator when handling and installing gaskets.

55

B.

Graphoil head gasket torque procedure: Start outtightening all nutsto5ft-lb(7 Nm),then

10

ft-lb

(14

Nm),

then to the torque specified in

the

ASEMBLY

TORQUES

section. Recheck all

nuts for correct torque. After the head nuts have been tightened once,

it

will be necessary to tighten each head nut to the specified torque asecond time. Follow thesame sequence shown in Figure

79.

Failure to re-

torque could result in a blown head gasket.

.HARDENED

WASHERS

-

HEAD

GASKET

6

LONG STUDSIHEAD

4

SHORT STUDS/HEAD

FIGURE

78.

CYLINDER HEAD WITH COMPRESSION WASHERS

Too

much torque will flatten the

compression washersand could

result in engine damage.

7.

Recheck torque before engine has run a total of

50

hours.

.

- - -

Is

LEFT

CYLINDER

RIGHT

CYLINDER

I

FIGURE

79.

HEAD BOLT TIGHTENING SEQUENCE

CYLINDER

HEAD

STUD TEST

AND REPLACEMENT PROCEDURE

This cylinder head stud replacement procedure should be used whenever replacing any of the top six studs on a NHC block. The use of a Helicoil is not a recommended repair procedure. If a Helicoil has been used, thecylinder block must be replaced. Graphoil head and intake manifold gaskets should also be used when replacing cylinder head studs.

Parts

Required

Part

No.

Description

520-091 2 Step stud 11 0-2987 Head gasket 154-221 9 Intake manifold gasket 420-0398 Drilling fixture (Reusable tool)

HEATTREATED

d

HARDENED

WASHERS

HEAD

GASKET

-

6

LONG STUDS (TOP)

4

SHORT STUDS (BOTTOM)

1. Disconnect the spark plug wires and remove the spark plugs and cylinder head air shrouds from

TORQUETOP

SIX

NUTS

TO

12

LB-FT.

(COLD)

TORQUE BOTTOM FOUR

NUTS TO

15

LB-FT.

each cylinder.

2. Remove the nuts and compression washers (do not remove the flatwashers) from the top six studs on each cylinder head (Figure 80). Each stud will have two compression washers and one flatwasher arranged in the sequence shown in Figure 81.

Do

not remove the nuts from the bottom four studs

before the test procedure is completed.

USE STUDS SHOWN ABOVE LINE

FOR

SECTION 1 STUD TEST

LEFT

CYLINDER

RIGHT

CYLINDER

NUMBERS INDICATE CORRECT

TIGHTENING SEQUENCE FOR

CYLINDER HEAD NUTS

FIGURE

80.

CYLINDER HEADS

FIGURE

81.

CYLINDER HEAD STUDS

3.

Replace the nuts and then test the top six cylinder head studs by tightening (use an accurate torque wrench) each nut to

30

ft-lb (40 Nm) of torque. Make a note of any studs that cannot be tightened to

30

ft-lb of torque.

4.

Remove the cylinder-head nuts, flatwashers, cylinder head, and head gasket. Discard the head gasket and remove any studs that could not be

torqued to

30

ft-lb (40 Nm) without thread pull

out.

5.

Examine the gasket surfaces of the block and

cylinder head for distortion or irregularities that could cause leakage. Check the head and block for warpage by laying a straight edge over the

length of the gasket surface.

If a 0.005

inch feeler gauge fits between the straight edge and gasket surface, the part must be replaced or milled flat.

A

maximum of

0.010

inch may be machined from

the cylinder block or head.

1

56

6.

7.

8.

9.

10.

11.

12.

13.

On some engines,

it

is possible that a groove

from

the old head gasket fire ring may be impressed

into the head and/or block. If this

is

the case, it is

essential that the part be replaced or milled

to

remove the imperfection. If all of the top six studs accepted 30 ft-lb of

torque without pulling out, the new head gasket

may be put on without replacement of the studs. If

this is the case, skip steps 6 through 12.

Fit the special repair fixture (Onan

Tool

#420-0398)

to the surface of the block. Use the studs shown in

Figure

82

and

two

cylinder head nuts to secure

fixture to head of block. Some applications may require that three or four

flatwashers be placed over the studs between the

block and fixture

to

space the fixture away from the

block. This will be necessary if the fixture does not

clear the sheet metal scroll backing plate.

Insert the small size bushing into the fixture over

the hole(s) with damaged threads and lock

it

in

place. With the brushing as a guide, drill out the damaged threads using a 27/64 size drill bit. If drilling out the holes on the

SIDE

of the block, drill through to the fourth fin (see Figure 83). If drilling out the holes at the TOP of the block,

it

will be necessary to remove the corresponding

intake or exhaust manifold. The drill bit should penetrate completely into the port but should not contact the opposite wall of the port (see Figure

83). Replace the small bushing with the large bushing

and lock into place. Using a 1/2-13 tap, carefully

form the threads, making sure there are full threads the entire length of the hole.

After all drilling and tapping is completed, remove the special fixture and repeat the same operation

-

on the other cylinder if necessary.

Remove the ridge around all new holes using a flat file or a 45" chamfer tool. When using a chamfertool, the depth of the chamfer should be 1/32 to 1/16 inch deep.

Apply screw thread retaining compound (Locktite 242) to the large end of each new step stud.

Install the stepped replacement stud, making

sure the entire stepped portion is below the

gasket surface. When putting a stepped stud into the hole that

penetrates into the exhaust port, it will be necessary to cut approximately 3/16 to 1/4 inch (3 threads)

off

the stepped portion of

the

stud.

No part of this stud may extend into the exhaust port or it will interfere with the exhaust manifold assembly.

Turn engine

so

that both valves areclosed. Using a flat scraper and/or wire brush, remove all lead and carbon deposits from the top of the piston, valve area, and cylinder head combustion chamber.

1

4.

Blow

out

all

residual

debris

and

metal

chips using

low

pressure

(35

PSI

or less) air.

If

a hole was drilled into either the exhaust or intake port, open the valve on that port and blow it out thoroughly.

Replace manifold if removed during the drilling and tapping operations.

FIGURE

83.

DRILLING

PROCEDURE

57

INTAKE MANIFOLD

GASKET REPLACMENT

1.

Remove the governor control rod from the governor arm and the breather tube from the air cleaner.

2.

Remove all

dirt

from the area around the intake

manifold and cylinder head interface. Remove the four bolts holding down the intake manifold assembly, and move the manifold

so

that

it

is

possible to work on the gasket area.

3.

Remove the intake manifold gasket. On some

models, the intake manifold gasket is tied to the exhaust manifold gasket. In these cases, use a cutting tool (chisel) to separate the intake manifold section of the gasket. Follow the outline of

the exhaust manifold as closely as possible when

cutting

.

4.

Install the new intake manifold gasket, making

sure

it

is properly positioned. Make certain the

outline of the gasket follows outline of port.

Installing the gasket upside down will allow air

leakage. This will cause lean operation and allow entry of dirt which will eventually lead to engine destruction.

5.

Reinstall the intake manifold tightening the four hold down bolts to

20

to 23 ft-lb (27-31 Nm)

of

torque.

6.

Reattach the governor control rod and air cleaner breather tube.

71

Do

nof

reuse anygaskefs which

have been damaged

by

fearing,

erosion, or galling.

58

Wiring Diagrams

The wiring diagrams in this section are typical for

NHC

and

NHCV

engines with

15-or20-amp flywheel

alternators and other options. The separate engine control wiring diagrams shipped with each unit should be used for troubleshooting. The following drawings are included herein:

I

1

I

1

i

I

I I

I

7--.

I

---

I

1

I

WI

CAUTION

!

REGULATOR

MUST

BE

GROUNDED

THROUGH

YDUNTINC

BOLTS

791

VR

I

MOUNTED BEHIND

BLOWER

WHEEL

AC

B+AC

STATOR

I

It

PHELON

15

AMP

ALTERNATOR

.

MOUNTED

WH\W

WR

WHEEL

-61

SYNCHRO

20

AMP

I1

ALTERNATOR

I

1

I

ENGINE CONTROL WIRING DIAGRAM

WITH

OPTIONS

*

WHEN

USED

59

-

CAUTIDH-

REGULATOR

MUST

BE

MWKTED

BLHlW

BWER

WHEEL

81

----

ii

S'I

I

WIRING DIAGRAM FOR FLYWHEEL

*

ALTERNATOR (PHELON

15

AMP)

(622-0386)

REF. DES.

BI BT

I

.El

&2

GI

JI

SI

s2

TI

VR

I

DESCRI PTlON

I

Starter & Solenoid-Engine Battery,

12

V.

Spark Plug

Alternator-Flywheel

15

Amp

Connector

Switch-Start, Run

Off

Breaker & Cap Assembly Ignition Coil (Onan) Regulator-Rectifier Voltage

WIRING DIAGRAM FOR FLYWHEEL

ALTERNATOR (SYNCRO

20

AMP)

(622-0382)

REF. DES.

BI

BT

I

CR

I

El.

E2

E3

JI

J2

MI

SI

52

53

TI

VRI

WI

GI

DESCRIPTION

Starter & Solenoid - Engine Battery,

12

V.

Rectifier Assy. Spark Plug Sender, Oil, Pressure Connector Connector

-

Faston

Meter

-

Oil Pressure

Switch -Start

Switch

-

Ignition

Breaker

&

Cap Assy. Ignition Coil Regulator -Voltage Lead Assy. Alternator

-

Flywheel

20

hp

60

Cummins Power Generation

1400 73rd Avenue

N.E.

Minneapolis, MN 55432 763-574-5000

Fax:

763-574-8087

Cummins and Onan are registered trademark

of

Cummins

Inc.