Generac Power Systems MC ALTERNATOR User Manual

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MC ALTERNATOR

DIAGNOSTIC REPAIR MANUAL

ISSUED JANUARY 1979

P.0, BOX 8, WAUKESHA. WISCONSIN 53186

PRINTED IN U.S.A.

51834

This Repair Manual is provided to aid the technician in the

analysis and repair of malfunctions that might occur in the

MC alternator or its engine. Keep the Manual in a safe place

and refer to it whenever necessary.

All information, illustrations and specifications contained

in this Manual are based on the latest product information available at the time of publication. Generac reserves the right to make changes in any product at any time without no tice.

GENERAC P.O.BOX 8

WAUKESHA. WISCONSIN 53186

PART I

GENERAL

Section 1.1

1.1.1

1.1.2

1.1.3

1.1.4

• 1.1.5

1.1.6

Section 1.2 Section 1.3

SPECIFICATIONS

Model Numbers

Fuels and Oils Torque Specifications (General)

Torque Specifications (Special) Sectional View Engine Specifications

WIRING DIAGRAMS SPECIAL TOOLS

SPECIFICATIONS

1.1.T-M0DEL NUMBERS

SECTION 1.1

Model No,

Wattage Capacitv Voltage

MC-35

6894 3500 3500 3800 120* 120* 120*

Maximum Amperes 29,2 at 120 V, 31,7 at 120 V.

Phase 1-Phase 1 1-Phase 1-Phase 1-Phase Frequency

Voltage

Regulation

Solid state voltage regulator maintains 120 Volts AC

(±27o) at 60 Hertz

MC-35

6895

MC-38

6938

MC-38

69 39

MC-40

6896 3800 4000 120* 120*

33.3 at 120 V.

1 -Phasel_1-Phase

60 Hertz at 3600 rpm

Batterv Charge 0-10 Amperes at 12 Volts DC

Gross Weight

(wet)

Engine Part No,

Bore

Stroke

Displacement

48078 48078

Approximately 127 pounds

48078 48078 48078

78 mm 62 mm

296 cc

Governed Speed 3720 rpm at no-load

Ignition System Starting System

Cranking Current

Average Fuel

Consumption Type of Fuel Pump

Mech,

12 Volt DC electric (Ring Gear)

Approximately 0,70 Gallons per Hour

Elec, Mech,

Solid State

Approximately 90 Amperes

Elec, Mech, ■ Elec,

MC-40

6897 .. 4000

120*

48078

'Factory connected for 120 Volt AC output only. Unit is reconnectable

to provide dual voltage output.

1.1.2-FUELS AND OILS RECOMMENDED FUEL

Use NON-LEADED gasoline. Leaded REGULAR grade gasoline is an acceptab

le substitute. Do not use any highly leaded, premium gasoline,

RECOMMENDED OIL

Use oil classified ”For Service SC, SD or SE”, as shown in the CHART at

USE OIL CLASSIFIED "FOR SERVICE SC, SD, or SE"

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

USE SAE 10 W

Of 10W-30OIL

^-----------------------------

USE SAE 30 OIL

USE SAE 20 W or 10W-30 OIL

right.

-10“F. 10“F. 32'F.

■22^C. •12.2'^C. O'C.

TEMFERATURE RANGE ANTICIPATED BEFORE NEXT OIL CHANGE

1,1-1

1.1.3- TORQUE SPECIFICATIONS (GENERAL)

STANDARD TORQUE VALUES

Grade 2

BOLT SIZE

1/4-20 1/4-28 5/16-18

5/16-24 3/8-16

3/8-24

7/16-14

7/16-20

1/2-13 1/2-20 9/16-12 9/16-18

5/8-11 92

5/8-18 105

3/4-10 3/4-16 180 140

7/8-9 7/8-14

1-8 300

1-14

DRY LUB

6 11 13 10

20 23 17 32 36 27

49 55

70 78

165 125

200 225

340 260

38 42 85 54 110 60

71 81

155 170

230

All Values in FOOT-POUNDS

DRY 4 5 10 8 17

31 24

55 42

120 150

170 270 295 230

395 435

590 680

Grade 5

LUB

13 21 15

27 38

58 65 84 93

115 130

205

305 335

455

5.10

DRY LUB 6 10 7

38 29

61 47

93 72 105 135 150

185 210

330 365

530'

585 450 795 610

Grade 7

16 24 18

80 105 115

145 160

250 280 420

405

DRY LUB

9 14

44 34 49 70 54 78

105 120 90 155 120 170

210 240

375 290

605 455 670

905 695

Grade 8

9 11 18 21

60 82

132 165

185

320

515

GRADE

BOLT HEAD

SYMBOL

1.1.4- TORQUE SPECIFICATIONS (SPECIAL)

Spark Plug Cylinder Head Bolts Connecting Rod Cap Bolts Engine Gear Cover Bolts

Blower Fan (Special M14 Hex Nut)

Rotor Bolt

Mechanical Fuel Pump Bolts

INCH-POUNDS FOOT-POUNDS

216-264 264-348 216-264

90-110 600-660 50-55 180-200

25-30

18-22 22-29 18-22

7.5-9

15-17

1.1-2

г=

о о

^ BREAKER ^

—

—J

1.1.6-ENGINE SPECIFICATIONS

INCHES METRIC

Spark Plug Gap Valve Spring Length Valve Spring Compression Length Valve Seat Width

Valve Tappet Clearance

Crankshaft End Play

Piston Diameter (at skirt)

Piston Pin Diameter

Width of Compression Grooves

Width of Oil Ring Groove

Width of Compression Rings

0.035

0.009 mm

1.2995 33.000 mm

1.0236

0.039-

26.000 mm 1-2 mm

0.079

0.0039-

0.1-0.2 mm

0.0078

0.0039-

0.1-0.3 mm

0.0118

3.067-

3.068

0.7080-

0.7086

0.0797-

0.0805

0.1584-

0.1593

0.0775-

0.0784

77.91-

77.93 mm

17.989 mm-

18.000 mm

2.025 mm-

2.045 ram

4.025 mm-

4.045 mm

1.970 mm-

1.990 mm

Width of Oil Ring

Ring End Gap

Maximum Permissible Out-of-Roundness

of Crankpin

Connecting Rod to Crankpin Clearance

Valve Spring Force

0.1560-

0.1570

0.0078-

0.0157

3.970 mm-

3.990 mm

0.2 - 0.4 mm

0.002 0.05 mm

0.001-

0.002

14.81-

19.76 lbs

0.030-

0.050 mm

kilograms

6.72-8.96

1.1-4

6896- 0

6897- 0

co гп

g i

Isa

CD XI

N5 ro

FUSE-

—14

@—

iTt>

L&ceND

C6 ChO«.B SOvKNOlO

c& c>*cutT BrmAiKClt

O OiOOB FP FoCL Pur^-ei.CCTRlC(ir »OPPl^tfcO^

F& FuBc BOwBnO'D

C FKikHt C«OUNO

>4M hOU« MtT«H

IM iCNiTlOM N\OOOUt

vS STikTO«

l-T CICMT

LOW OlC BW>TCm

»cm p«iNTto Cimcj'T mo*^«o

s m-TK«!«« sc «Tk.«Te<« &OLBNo>o Sw BTOP-ST^RT Switch

i^imi tmut

-----

REMOTE PANEL

STO

0 1

o—

—o

TART

----

1 e

ffh

-2

------

MODELS 6894-1,-2

6895- 1,-2

6896- 1,-2

6897- 1,-2,-3 6938- 0 6939- 0

со

о о

оо to о со

4ï^

ОО

СО

RED CONNECTOR PLUG

RED RECEPTACLE

oKslCel

CjlLjlCa

11 '—

120

CUSTOMERS CONNECTIONS

FACTORY WIRING CONNECTIONS 120 VOLTS ONLY

120VT 120V.

•—4*—>

-240V, -

CUSTOMER CONNECTIONS

-CD □ d]

-----

-L

[4] rs: Cel

RED CONNECTOR PLUG

RED RECEPTACLE

RECONNECTED FOR 120/240 VOLT

OUTPUT

1.2-5

SECTION 1.3

SPECIAL TOOLS

ELEHTRICAL TEST PLUG

The Electrical Test Plug facilit

ates the testing of electrical components in circuits that pass through the red and white stator can receptacles, or through the Ignition Module receptacle. Use

the Test Plug in any diagnostic test that calls for connection of the VOM test probes to pins in

these receptacles. Order Part No.

27069.

INSULATION BREAKDOWN TESTER

Resistance testing of alternator compon ents with an Ohmmeter is generally valid. Such resistance tests will nearly always indicate the presence of an open or shor ted condition. However, some malfunctions do not become evident until an electrical load is applied across the defective'com ponent. The insulation breakdown tester permits a component to be tested under a simulated load condition, by applying a selected voltage to the component. Follow the tester manufacturer’s instructions strictly when using the tester.

SPARK T.ESTER

The Spark Tester is used to check for pro per ignition spark with the engine cranking. Order Part' No. 41503.

ROTOR REMOVAL KIT

The Rotor Removal Kit consists of a 3/8-24 TAP, 3/8-24 BOLT, and threaded studs o'f varying lengths. The kit is used for remo val of the rotor. Order Part No. 41079.

LOAD BANK

The Load Bank is used to apply an

electrical load to alternators.. The unit is equipped with a Volt meter, Ammmeter and Frequency Me

ter, as well as the necessary switches for selecting the desir

ed load. Specify Model No. 5515,

1.3-2

PART II

TROUBLE DIAGNOSIS

Section 2.1

2.1.1

Section 2.2 Section 2,3

- DIAGNOSTIC FLOW CHARTS

- Introduction Engine won’t Crank

Engine Cranks, won’t Start Engine starts hard - Runs Rough

Switch set to STOP - Engine Keeps Running AC Voltage Low AC Power Low AC Voltage High No AC Voltage

- Diagnostic Tests

- Battery Charge Circuit Tests

SECTION 2.1

DIAGNOSTIC FLOW CHARTS

2.1.1-INTROUUCTION

The DIAGNOSTIC FLOW CHARTS that follow are intended for use with the DIAGNOSTIC TESTS in Section 2.2, Test numbers assigned in the FLOW CHART are identical to the numbers assigned to specific tests in Sec

tion 2.2.

ENGINE WON’T CRANK

TEST 1

15 Amp

Page

2.2-1

Fuse

BAD

Replace Rise

TEST 4 Starter Solenoid

I i

|Repl

TEST 7

Page 1

2.2-2|iGOODZ^

ace

Page] Starter Ring Gear

______

BAD

9 0/,

“GOODI^

'GOOD

TEST 2 Page Battery

9.2-1*—GOOD--^ Start/Stop

2.2-1

BAD

Recharge or

Replace

;GOOD

TEST 5 Starter

Motor

L___1

--------1

Replace

ENGINE

SEIZED

Page 1

2.2-3 |—■ GOODI^

GOOD

7F1

idJ

BAD

TEST 3

Cr-r,- i-^U

Switch

~1 r

Page

2.2-2

BAD

Replace Switch

TEST 6 Page Starter Drive Gear

2.2-4

Replace

Repair

Replace

ENGINE CRANKS, WON’T START

TEST 8

Check

Spark

Page

2.2-^’

IF SPARK CHECKS GOOD

GO TO TEST 15

TEST 11

Spark Plug

Page

2.2-5

BAD

TEST 9

________ _______

OIL LEVEL LOW |

IFILL TANK

........-nnnn-

TEST 12

Ignition

Module

IbadI

Page

Page I

2.2-6 ^GOOD =CH

TEST 10

Low Oil

Switch

ba:

REPAIR/REPLACE

TEST 13

Ignition

Stator

IBAD

Page

2.2-5

Page

2.2-6

Replace

TEST 14 Page

Ignition *2 2-7

Coil I * I

I REPLACE

TEST 16 No Fuel

Flow

Page

2.2-8

|Replace|

IF SPARK CHECKS GOOD I

TEST 17

4 Amp

.BAD Fuse

;GOOD:

GO TO TEST 15

:G00D:

Page

2.2-8

:good:

¡Replace

TEST 15 Low Fuel

LOW

FILL TANK

TEST 18 Printed

Circuit

Page

2.2-8

Page

2.2-9

GO TO TEST

2.1-2

BAD

Except 6897-4 See Section 2.4

IREFIACEI

;G00D;

GO TO TEST 19

TEST 19 Fuel

Filter

Page

2.2-9

IGOOD;

TEST 20 Fuel Lock-Off ; Solenoid

Page

L2-10

____

TEST 21 Fuel Pump |2.2-lC

Page

bad!

REPLACE

TEST 22 Page Check

Installation_

IF FUEL FLOW IS GOOD

GO TO TEST 23

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

2.2-11

ADJUST

JETS

test:! BAD

1 .

REPLACE

:GOOD:

TEST 23 Pagel Carburetor 2.2-11”^^^

REPLACE CARBURETOR

CHANG E¡f>

TEST

BAD

REPLACE

TEST 24 Page

Compression!.2-13

GOOD

ICO TO TEST 29

CHECK FLOAT Z^BAD^Z^^ SEAT

CHECK 1

FLOAT ::;>bad;i::>

LEVEL

REPLACE SEAT

ADJUST

KLOAT i

LEVEL

GO TO TEST 27

TEST

;BAD

TEST 25 page! ^

Vi n A J _ I

Head

Gasket^

_____

| o

BAD

REPLACE GASKET

Itest

TEST 26| Page Valves 2.2-14

REPAIR

[TEST

2.1-3

IF COMPRESSION IS GOOD, GO TO TEST 29r

TEST 27 Rings 2

.. 1 i ’

BAD

REPIACE

TEST

Page

-.2-14

■good:

TEST 28 Page Cylinder 2.2-14

\ I I ‘ *

BAD

REPAIR

TEST 29

TEST

ENGINE STARTS HARD - RUNS ROUGH

Timing

Page

Z.2-14

2.1-4

REPAIR

REPLACE

SWITCH SET TO STOP - ENGINE KEEPS RUNNING

TEST 3 jPagej

Replace Switch

REPAIR

2.1-5

A-C VOLTAGE LOW

TEST 33 Check

Frequency

B/1Id

TEST 32 Governor

2.2-17 ____

2.2-17

Page

:good

Page

A-C POWER LOW

2*1-6

A-C VOLTAGE HIGH

TEST 36

Check Output ; Voltage

TEST 36 Check Output Voltage

Page

>.2-19 ____

Page

^2-19

ZZBAD

CHECK CUSTOMER WIRING|<r^IZZZ.GOOD

NO A-C VOLTAGE

TEST 38 Main

Circuit .

Breaker

Page

^2-20

____

:good:

TEST 37 Sensing Transformer

BAD

Replace

Transformer

TEST

TEST 39

check Rotor2 2-20“

j Paee

12.2-19

J_____

Pag£

GOOD

Check Customer

____

Wiring

TEST

TEST 40 Check Field Boost

Check Wire ^^0-

No. 14

____

Page

2.2-21lC>

BAD

REPLACE

TEST

CHECK VOLTAGE* _

TO ROTOR I

\ t

BAD

Jcheck No. 4 Wire

1 for 12 Volts

^~li

GOOD

BAD

¡REPLACE

¡TEST

IGOOD

testIcT^

________Iz__________

.•Replace Printed "[Circuit Board

■ 2.1-7

SECTION 2.2

DIAGNOSTIC TESTS

TEST 1-15 AMPFUSE

Remove and visually inspect the 15

Amp Fuse. Replace, if Fuse element

has melted. A more thorough check

may be made with a Volt-Ohm-Milli-

ammeter, as follows

1. )-Set VOM to ”+DC” and to "Rxl” scale.

2. )-Connect meter test probes and

”Zero’^ the meter.

3. )-Connect meter test probes to

Fuse ends. Meter needle should

swing upscale to ’^0” ohms (continu ity). If meter needle does not move

upscale, replace the Fuse.

RESULTS:-Fuse tests bad

Fuse tests good

TEST 2-BATTERY

Check Battery condition, as well as

the condition, cleanliness and sec

urity of battery cables and connec

tions .

RESULTS:-Battery, cables or connections,

check bad

Battery, cables or connections,

check good

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

.......

.Install new 15 Amp Fuse .Continue tests

.Recharge or replace de

fective Battery. Repair, clean or replace defect ive cables or connection

.Continue tests

2.2-1

TEST3-ST0P/START SWITCH

Left Hand

10 (Ground)

Remove 15 Amp Fuse to disconnect

starting circuit. Remove panel

top cover. Disconnect wires from

switch terminals to prevent int

eraction. Set VOM to "+DC” and to "Rxl” scale, then zero the meter. Connect meter test probes to the

switch center and right hand ter

minals (as viewed from switch

rear). Meter needle should not

TT,^-<rQ H QT.ri rph at START - meter

Connect VOM test probes to Switch

center and left terminals (as vi ewed from switch rear). Hold the Switch at START - meter needle

should not move. Release the Switch

to NEUTRAL - meter needle should not move. Hold the Switch at STOP needle should swing upscale to ”0",

.Install new Stop/Start Switch .Connect Switch wires, install

top panel and 15 Amp Fuse,

Continue tests.

A.)- Set Stop/Start Switch to START

and back to NEUTRAL several times.

An audible ’’click" should be heard

as the solenoid actuates.

2.2-2

RESULTS:- Solenoid actuates, engine

does not crank

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

Continue tests in Paragraph B

Solenoid does not actuate.•...Continue tests in Paragraph D

B. )- Set VOM to ”+DC” and to a scale greater than 12 Volts DC. Connect

the NEGATIVE (COMMON) test probe to ground. Connect the POSITIVE (+) probe to the battery cable connection on the solenoid. Meter should in dicate approximately 12 Volts DC.

RESULTS: - Meter reads 12 Volts DC

Meter reads less than 12

.....

....

Continue tests in Paragraph C

.Check for open or shorted wire

Volts DC (or loose connection) between

Battery and Starter Solenoid

C. )- Connect POSITIVE (+)'meter test probe to starter cable connection on solenoid. Connect NEGATIVE (COMMON) probe to ground. Hold Stop/Start Switch at START - meter should indicate approximately 12 Volts DC.

RESULTS:- Meter does not read

12 Volts DC.....

Meter reads 12 Volts and

..........

.....

...Install new Starter Solenoid

Continue tests in DIAGNOSTIC

Solenoid checks good FLOW CHARTS

D. )- Set VOM to ”+DC” and to a scale greater than 12 Volts. Connect the

meter POSITIVE (+) test probe to one of the small terminals on the sol

enoid. Connect the remaining probe to ground. Meter needle should read approximately 12 Volts DC. With one probe'still connected to ground,

connect the remaining terminal to the other small terminal on the solen

oid - meter should indicate approximately 12 Volts DC.

RESULTS:- Meter indicates 12 Volts......Continue tests

Meter does NOT read 12 Volts..Repeat Tests 1, 2 and 3. When

sure that these tests are good and 12 Volts is not indicated

in Test 4.D., replace solenoid

TEST 5-STARTER MOTOR

Set VOM to ”-hDC” and to a scale greater than 12 Volts DC. Conn ect VOM positive (4-) test probe to the Starter terminal lug and

COMMON (-) test probe to frame

ground. Hold Stop/Start switch

at START. Meter should indicate

approximately 12 Volts DC and starter motor should run.

Starter runs.................................Continue tests

Meter indicates 12 Volts DC,

Starter does not run

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

Meter does not indicate 12 Volts

........

Replace Starter

Check Starter cable

2.2-3

TEST 6-STARTER DRIVE GEAR

A.)-Hold Stop/Start switch at its

START position and listen for the

starter motor. If motor runs free

B,)-Visually check Starter pinion

for damage, if damaged, replace

pinion. ly (without load), remove Starter drive cover.

C,)-To replace Starter pinion assembly, remove lock nut, spring retain

er, and pinion. Install a new pinion, spring, spring retainer and lock

nut. Tighten lock nut to 90-110 inch-pounds, DO NOT LUBRICATE PINION

SPLINES,

RESULTS:- Starter drive checks good

Starter drive is defective.,,,,,,,.................

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

.Continue tests

Replace

TEST 7-STARTER RING GEAR

Inspect Starter Ring Gear for dam age, Ring Gear and Fly^dieel are

heat shrunk onto Rotor aaaembly.

If replacement is necessary, ent

ire assembly must be replaced.

TEST 8-CHECK SPARK

Disconnect spark plug lead from engine spark plug and connect to Spark Tester (Part No, 41503).

Connect Tester clamp to engine

spark plug. Crank engine - spark tester should emit a blue, snappy spark.

RESULTS:- Spark tests good...

.......

...Go to Test 15

Spark tests bad,

......

2.2-4

Continue tests

.....

........

TEST 9-OIL MAKE-UP TANK

Check oil level in Oil Make-Up Tank. If oil level is below OIL CHANGE LEVEL arrows, fill tank

with recommended engine oil and

recheck for proper start.

TEST 10-LOW OIL SWITCH

Remove Low Oil Switch Cover and

slide it down the Switch wires to expose the Switch terminals. Set VOM to "+DC" and to "Rxl" scale, then zero the meter. Con

nect one meter test probe to the

lower terminal on side of switch.

Connect remaining test probe to ground terminal on bottom of the switch. Move switch actuating le

ver DOWN (simulated low oil cond

ition) - meter needle should swing upscale to ”0”. Raise the

switch actuating lever (FULL con dition) - meter needle should

drop downscale to infinity.

LOW OIL

SWITCH'

TEST PROBES

mr^

ooj

METER READS INFINITY

METER READS

•0"

RESULTS:- Switch tests bad..

Switch tests good.

CAUTION

.Replace switch .Continue tests

When reassembling Switch cover, make sure float arm is in place

on top of switch actuating lever, or switch will not function.

TEST 11-SPARK PLUG

Remove engine spark plug. With spark plug lead connected to plug, ground

the spark plug against the engine block and crank engine. Spark plug should emit a sharp, snappy, blue spark,

RESULTS;- Spark Plug bests bad..,....................Replace Spark Plug

Spark Plug checks good,,,.,,,.................

Continue tests

2.2-5

TEST 12- IGNITION MODULE

Unplug the Ignition Module from

its receptacle on the side of the stator can. Carefully inspect mo dule and receptacle pins for. dam

age, bending or "pushing out"

from their retainers. Plug in a

known good "shop" module and

check for normal sparking at the spark plug.

Ignition

Module

Ignition Module

Receptacle

RESULTS:- Ignition Module tests good

Ignition Module tests bad

........................Replace

TEST 13- IGNITION STATOR

A. )-Trig;g£r Coil:- Set VOM to "+DC"

and to "Rxl" scale. Zero the meter.

On the DC Control Board, unplug the

connector plug from its receptacle

to prevent interaction. Also unplug the Ignition Module from its recep tacle. Insert one meter test probe into Pin No. 3 of the Ignition Mod

ule Receptacle. Connect tha remain

ing test probe to frame ground. The

meter needle should swing upscale

and read Trigger Coil resistance (a-

bout 7 Ohms), RESULTS:- Meter needle does not move.

Meter needle swings upscale,

and indicates approximately 7 Ohms resistance

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

.Check Wire No. 25 between

Ignition Module receptacle and Ignition Stator for an "open" condition. If Wire

No. 25 is good, replace

Ignition Stator

.Continue checks

Continue tests

Trigger

Coil

B.)- Charge Coil:- Set VOM to "+DC" and to "RxlO" scale, then zero the meter. Insert one meter test probe into Pin No, 2 of the Ignition Mod ule receptacle. Connect the remaining test probe to frame ground. The meter needle should swing upscale.and indicaie approximately 250 Ohms

resistance.

2.2-6

RESULTS;— Meter needle does not move«

..Check Wire No, 8, between

Ignition Module receptacle and Ignition Stator Charge Coil for an ''open” condit

ion, If Wire No, 8 checks good, replace Ignition Sta tor,

Meter indicates approximately 250.

..Continue checks

Ohms

REINSTALL CONNECTOR PLUG INTO DC CONTROL BOARD RECEPTACLE AND IGNITION MODULE INTO ITS RECEPTACLE BEFORE CONTINUING.

TEST 14- IGNITION COIL

A.)- Primary Winding;- Set VOM to

"Rxl” scale and to ''+DC”. Zero the

meter. Connect the positive (+)

test probe into Pin 4 of the Igni tion Module receptacle. Connect the negative (common) test probe to frame ground. Meter needle

should swing upscale to nearly "O",

RESULT;- Meter needle does not move.............Replace Ignition Coil

Meter indicates nearly "O”.....................Continue test

B,)- Secondary winding; - Set VOM to '’RxlK” and to "+DC”. Zero the met

er. Install spark plug lead into Ignition Coil. Connect one meter test

probe to spark plug end of spark plug lead and the remaining probe to

frame ground. Meter needle should swing upscale and indicate approxim

ately 5000 Ohms (+10%).

RESULT;- Meter needle does not move.......Check spark plug lead for

open condition. If lead is

good, replace Ignition Coil

Meter reads approximately.....................Continue test

5000 Ohms

CAUTION

To prevent damage to Ignition Coil, make sure spark plug, lead and

spark plug are installed and grounded to engine before cranking.

2.2-7

TEST 15:- LOW FUEL

The motor home engine and the alt ernator engine should "share” the vehicle fuel tank, through a dual fuel pickup tube arrangement. See illustration at right. To prevent the alternator from depleting the

fuel tank, the alternator fuel

pickup tube is usually several in

ches shorter than the vehicle eng ine tube. Thus, the alternator may

be "out-of-gas" while the vehicle

engine has a sufficient fuel supply

Make sure the alternator fuel supply line is NOT connected into the ve hicle engine fuel supply line. If the vehicle engine is running, the

alternator engine may be starved of fuel. When the vehicle engine is

not running, the alternator may drain the vehicle engine fuel line (and

even the vehicle engine carburetor). The latter will result in hard

starting of the vehicle engine.

TEST 16:-NO FUEL FLOW

Disconnect fuel line at Carburetor inlet fitting. Place open end of

fuel line into a suitable contain er, then crank engine. Fuel should

pump from open end of fuel line.

If little or no fuel comes from

fuel line, check in-line filter for clogging. Replace fuel line and fi lter, if filter is clogged.

RESULTS:- Little or no fuel flow observed

Fuel flow is good

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

TEST 17:- 4 AMP FUSE

The 4 Amp Fuse is equipped with a

Fuse Puller Tab for easy removal. Remove the Fuse from the Printed Circuit Board and test in same

manner as 15 Amp Fuse (Test 1). If

Fuse is defective, replace.

(NOTE:-Model 6897-4 has no 4 Amp

Fuse. See Section 2.4.)

2.2-8

i 1

j "

■j

'I' >

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

----

CARBURETOR

- IN-LINE FILTER

— FUEL LINE

Continue tests

Go to Test 23

TEST 18;- PRINTED CIRCUIT BOARD

A.)- Depress Printed Circuit Board

connector plug locking tangs and remove connector plug. On the conn

ector plug, locate Pin 4 to which Wire No. 20 attaches. Set VOM to AC and to the 2.5 volt scale. Connect one meter test probe to connector plug Pin 4, Connect the other test probe to frame ground. Crank engine. Meter should indicate a small puls

ing voltage. This is the pulsing voltage from the Ignition .Stator

trigger coil, which energizes circ uit board components.

Wir« No. 14 Connection

terminal

Strip

, ■ ■■■ ■ ■ —Q— . ■ ■ -1

rs —^ \— ^ -1

__________________________________________

Printed Circuit Board

I Module

- EDflO

Ignition

__J— O

1--1 —' jc 0 o'olj

Connector Plug

Receptacle

Connector Plug (viewed from Wire end)

NOTE:- For Model 6897-4, refer

to Section 2,4,

RESULTS:- Meter indicates pulsing voltage

.........

.,,Continue tests

No pulsing voltage indicated,..Check Wire No. 20, between

connector plug and terminal strip, and Wire No. 25 betw een terminal strip and Igni tion module for open or shor ted condition

See illustration above. Locate the Wire No, 14 connection at terminal

strip. Plug the Printed Circuit Board connector plug into its recept

acle. Set VOM to '’+DC” and to "50V” scale. Connect positive ( + ) meter

test probe to terminal strip Wire No. 14 connection. Connect remain ing test probe to frame ground. Crank the engine. Meter should swing

upscale and indicate 9-12 Volts DC.

RESULTS:- Meter indicated 9-12 Volts

....

Continue tests in Diagnostic

Flow Charts

Meter did NOT read 9-12 Volts..Check Wire No. 14 (between

PCB and terminal strip) for open or short. If wire is

good, replace Circuit Board

TEST 19:- FUEL FILTER

Remove and replace fuel filter. Make sure arrow on filter body-

points toward the solenoid oper

ated Fuel Shutoff Valve. Repeat Test 16 (NO FUEL FLOW).

TEST 20;- FUEL LOCK-OFF SOLENOID

A.)- Locate Wire No. 14 between the

Fuel Lock-Off Solenoid and terminal

strip. Disconnect the wire at its terminal strip connection. Crank en gine. While cranking, touch Wire No. 14 to its terminal strip connection.

Fuel solenoid should actuate. If the

unit has an electric fuel pump, a

noticeable change in fuel pump sound will be detected.

RESULT:- Solenoid did not actuate.,.,,

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

Go to Paragraph B

Solenoid actuates....Continue tests in DIAGNOSTIC FLOW CHARTS

B.)- Disconnect Fuel Lock-Off Solenoid Wire No, 14 at the terminal st rip, Set VOM to "+DC” and to ”Rxl” scale. Zero the meter. Connect one

meter test probe to the terminal end of Wire No, 14, Connect the rem

aining test probe to frame ground. Meter needle should swing upscale to indicate resistance of solenoid windings.

RESULT:- Meter did not swing upscale,

.Check Wire No, 14 between sol

enoid and terminal strip for

open condition. Also check the

solenoid ground wire and conn ection

Meter needle swung upscale,,,

.Replace Fuel Lock-Off Solenoid

and solenoid did not actuate

in Paragraph A

TEST 21:- FUEL PUMP

UNITS WITH ELECTRIC FUEL PUMP

A.)- Disconnect Wire No, 14 at the Fuel Pump, Set VOM to ”+DC' and to

”Rxl” scale. Zero the meter. Connect one meter test probe to the Fuel

Pump Wire No, 14-, Connect the remaining test probe to frame ground.

Meter needle should swing upscale and indicate approximately 50 Ohms',

RESULT:- Pump tests good

Pump test^ bad,

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

......

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

Go to Paragraph B

Replace pump

C,)- Set VOM to "+DC" and to 50V scale. Disconnect Wire No, 14 at the Fuel Pump, Connect POSITIVE (+) meter test probe to terminal end of Wire

No. 14, Connect COMMON test probe to frame ground. Crank the engine -

meter needle should deflect upscale and read approximately 12 Volts DC

(battery voltage),

RESULT:- Meter needle daes NOT swing upscale

Meter indicated approximately 12 Volts

2.2-10

.......

.....

Go to Paragraph C Replace Fuel Pump

C.)- Check Wire No. 14, between Fuel Pump and terminal strip, for open

or shorted condition,

RESULT:- Wire No. 14 checks good

Wire No. 14 cheeks bad

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

UNITS WITH MECHANICAL FUEL PUMP

Disconnect Piomp Outlet Line at the carburetor inlet. Connect a press

ure gauge to the line. Disconnect

Pump Inlet Line at the £ue-l lock-

off solenoid and immerse line in clean gasoline. Crank engine. The pressure gauge should indicate 1-

3 psi.

RESULT:- Pressure gauge read 1-3 psi

Pressure gauge does -not read 1-3 psi

Repair/replace Wire No. 14

........

Continue Diagnostic tests

Continue Diagnostic Tests

...........

Replace Pump

TEST 22;- CHECK INSTALLATION

Check alternator installation for:-

1. )- Any other filter screens in the fuel supply line from gas tank. If other filters are found, check for clogging.

2. )- A Shutoff Valve in the fuel supply line. Make sure Shutoff Valve is OPEN.

3. )- Anything that might restrict cooling air flow, such as air inlet or exhaust openings too small, clogged air inlet screening, etc. If cooling air flow is inadequate, interior compartment tempera tures will be high resulting in possible fuel line vapor lock,

4. )- Alternator fuel pump located too high above fuel supply tank.

Maximum vertical lift for MC units with an electric pump is app

roximately 18 inches, for mechanical fuel pumps approximately 9 inches.

TEST 23- CARBURETOR

This test covers the procedures for adjustment of the carburetor Idle Speed Stop Screw, Idle Mixture Adjusting Screw, and High Speed Jet Ad

justing Screw. In addition to these adjustments, the float valve and

its seat should be checked, as well as the float level.

2.2-11

A.)-Turn High Speed Jet Adjusting

Screw clockwise until it just bot

toms. DO NOT USE EXCESSIVE FORCE. Then turn High Speed Jet Adjusting Screw counterclockwise about

turns. Perform the same initial ad

justment on the Idle Mixture Adjust

ment Screw. This initial adjustment

should permit the engine to be star

ted and warmed up.

Automatic Choke

. High Speed Jet

Adjusting Screw

Throttle Lever

Idle Mixture Adjusting Screw

RESULTS:- Engine starts

Engine will not start

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

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

Go to Paragraph B Go to Paragraph D

B. )- Set VOM to "250V,” scale and to "AC". Connect the meter test leads

to a convenient AC outlet powered by the alternator. Hold the Carburet or Throttle Lever against its Idle Speed Stop Screw, Adjust Idle Speed

Stop Screw until meter indicates 60 Volts a-c. When a 60 Volt reading

is obtained, turn Idle Mixture Adjusting Screw until voltage starts to drop off. Then turn the screw in the opposite direction until voltage reading again starts to decrease. Finally, reverse direction again and

turn the screw until the highest voltage reading is obtained. Release

Throttle Lever and let engine accelerate and stabilize,

C. )- With engine running at governed speed, apply a normal load to the alternator. Connect an accurate frequency meter to the unit’s a-c out put, Turn the High Speed Jet Adjusting' screw slowly clockwise then counterclockwise until the highest frequency is obtained. When the Jet is set for the highest possible frequency, turn adjusting screw count

erclockwise 1/8 turn.

RESULTS:- Engine starts and runs normally............Discontinue Tests

Engine will not start or starts and runs rough

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

Go to Paragraph D

D.)- Remove Fuel Bowl from Carbur etor Body. Inspect Float Valve, Seat and Gasket for damage, dirt or wear. Replace defective compon ents. Also check for proper Float setting. Top of Float should be

0.070 - 0.110 inch below Carburet or Body mounting Flange. See illu stration at right.

2.2-12

RESULT:- Float Valve, Seat, Gasket and

Float level are good Float Valve, Seat, Gasket or Float level check bad

TEST 24:- COMPRESSION

A.)-Insert a standard compression

gauge into engine spark plug hole.

Open throttle wide open and crank

engine. Compression should be app roximately 75-85 psi (cold) or 95105 psi (hot).

.........

........

-...Continue Diagnostic Tests

-Replace or adjust, then test

COMPRESSION GAUGE

SPARK PLUG REMOVED

RESULT:- Compression reading good

Compression reading low.......................Continue tests

B,)- Squirt a few drops of clean engine oil into spark plug hole on en

gine cylinder head. Repeat compression test. If compression reading is

higher than was obtained in Paragraph A, ring or cylinder wear is indi

cated, If little or no difference in compression was noted, trouble may

be due to head gasket leakage, worn valves, etc.

RESULT:- Noticeable increase in

compression obtained...............

Little or no increase in compression.

TEST 25:- HEAD GASKET

Crank the engine. A "hissing" sound at the spark plug indicates the plug is loose or broken. Likewise, "hiss ing" at the cylinder head indicates loose head nuts or a leaking head gasket. Tighten loose spark plug, re place broken spark plug using a new plug gasket. If cylinder head leaks, check for warped cylinder head and for a defective head gasket. Refer to engine section of manual and to TORQ

UE SPECIFICATIONS (SPECIAL).

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

Go to Test 29

Go to Test 27 Go to Test 25

2.2-13

TEST 26:- VALVES

Remove valves. Clean all parts in non-flammable solvent. Remove all carbon. Replace damaged or distor

ted valves. If valves are useable, lap them as outlined in engine se ction. Check for correct tappet

clearance as outlined in engine

section of manual.

TEST 27:- RINGS

Check for broken or worn rings. Check ring clearance-in piston

grooves and ring gap. Refer to engine section of manual.

Valve

Roller Spring Retainer

Valve Spring

Valve Spring Retainer

Tappet

TEST 28:- CYLINDER

Inspect cylinder walls for burning, scoring, or scratching. Check cylin der inner diameter. Refer to engine section of manual for inspection requirements.

TEST 29:- TIMING

This Pol« Must Attract Th« North Soaking Poia Ot A Magnatic Compass

The ignition magnet is retained to

the fan with a special adhesive

which is cured at 300°F. for 1 hour

(or 265°F. for 1% hours) after ins

tallation. The ring gear is heated and pressed over the fan and magnet assembly. The entire assembly is

then balanced as a unit, and finally heated and epoxied into place over the rotor shaft. Any damage to the Rotor, Fan, Magnet or Ring Gear is cause for replacement of the entire assembly.

2.2-14

Magnai Location astabilshas Timing At 21* BTDC

Timing is established at 21 BTDC by the physical location of the magnet

on the fan. Thus any damage that results in a physical change in the magnet's location will cause an "out-of-time" condition. Check for a da maged key or keyway that might have caused slippage of the fan on the

rotor shaft.

TEST 30:- CHOKE

A.)-Crank the engine. The Choke

Solenoid should pulse from Choke

OPEN to Choke CLOSED position at

a rate dependent on ambient tem perature.

RESULTS:- Choke movement is good

Choke does not move

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

Go to Test 31, PRE-CHOKE

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

Go to Paragraph B

B.)-Check the Choke assembly for binding or sticking caused by im

proper alignment, dirt, etc. Move Choke back and forth with fingerthere should be no evidence of

binding or sticking.

RESULTS:- Choke is binding..,

Choke moves freely,

.Adjust or clean choke linkage

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

Go to Paragraph C

C.)- Loosen the two Solenoid Adjusting screws. Adjust axial movement

of solenoid plunger so that, with carburetor choke plate closed, the choke solenoid plunger is bottomed. Tighten the two adjusting screws and check again for correct choke action,

RESULTS:- Choke solenoid pulls in normally..............Go to Test 31

Solenoid does not pull in,................Go to Paragraph D

2.2-15

D.)-Set VOM to ”+DC'’ and to ”50V.” scale. Connect the positive (+)

meter test probe to the Wire No. 91

terminal on the choke solenoid and

the remaining test probe to frame ground. Crank the engine - meter

needle should swing upscale and in

dicate a steady 12 Volts DC.

RESULTS:- Meter does not indicate IZ Volts....Check Wire No. 91 for an

open or shorted condition

Meter indicates 12 Volts DC................Go to Paragraph E

E.)- Set VOM to "+DC” and to ”50V.'' scale. Connect the positive ( + ) me ter test probe to the Wire No. 90 terminal on the choke solenoid and the common (-) test probe to frame ground. Crank the engine - meter nee dle should indicate a pulsing voltage as choke pulses open and closed.

RESULTS:- No meter needle movement

Meter test is good but choke

does not actuate.....................Replace Choke assembly

TEST 31:- PRE-CHOKE

With the choke Bi-Metal at ambient

temperature, the carburetor choke plate should be approximately 1/8 inch away from its full open posi tion (toward the closed position). If necessary, loosen the bi-metal adjusting screws and move the bi

metal to obtain this setting. This

is the "Pre-Choke" position.

......

Replace Printed Circuit Board

(Model 6897-4:-Replace Choke

Pulse Module [CM]. See Sect-

jL 2 ^ )

2.2-16

TEST 32;- GOVERNOR

A.)- Adjust Carburetor as outlined in Test 23, The Carburetor must be

adjusted BEFORE attempting to adjust the Governor,

RESULT Problem is corrected...........................Test completed

Engine ’’hunts’’ and/or a-c voltage

or frequency is incorrect.................Go to Paragraph B

_ Carburetor

Throttle Lever

B,)-Make sure Governor Spring is

connected to Governor Arm and to

Governor Adjusting Screw, Loosen Engine Governor Shaft Clamp Nut and turn Engine Governor Shaft counterclockwise as far as it

Engine Governor Shaft Clamp Bolt, Nut and Washers

will go. Then tighten Governor Shaft Clamp Nutand torque to 110 inch-pounds.

Engine Governor Shaft

RESULT:- Engine runs normal, provides

62 Hertz at no—load..........................Test completed

Engine hunts and/or a-c voltage or frequency is incorrect

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

Go to Paragraph C

C,)- With engine running, adjust hex nuts at end of Governor Adjust

ing Screw to obtain 62 Hertz at no-load. One hex nut serves as a jam

nut - make sure this nut is tight when 62 Hertz is obtained,

RESULT:- Engine runs normal,,,,.,,"...................Test completed

Engine hunts

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

Set Carburetor for richer mixture

NOTE

All mechanical governors have a normal offspeed fluctuation, This is the reaction time of the governor,

TEST 33;- CHECK FREQUENCY

Use an accurate Frequency Meter to check alternator output frequency. Frequency should be 62 Hertz at no-load. With a normal electrical load applied, frequency should be 59-62 Hertz and stable (disregarding the normal offspeed fluctuation).

2.2-17

TEST 34:- EXCITATION WINDINGS

Remove the

assembly.

alternator front panel

Disconnect the white connector plug

from its receptacle on the stator can. On the receptacle, locate Pin No. 2 and 6 to which Wires No. 2 and 6 attach. Set VOM to ”+DC’' and

to "Rxl” scale, then zero the meter. Connect one meter test probe to re ceptacle Pin No, 2, Connect the re

maining test probe to receptacle Pin No. 6. Meter needle should swing up

scale and read approximately 1,1

Ohms, This is the resistance of the

excitation winding,

RESULT;- Meter needle does not move

Windings check good

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

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

,,,Continue diagnostic tests

Replace stator

TEST 35:- CARBON DEPOSITS

Excessive carbon buildup in the engine combustion section can serious ly affect engine power. Carbon deposits should be removed every 500 operating hours, whenever the cylinder head is removed, or when prob lems are encountered. Refer to the engine section of Manual for cylin der head removal and installation procedures. Cylinder head bolts must

be properly located and properly torqued.

RESULT:- Power output is normal............

Problem is still encountered,

2.2-18

......

........

Discontinue tests

Continue diagnostic tests

TEST 36:- CHECK VOLTAGE

Disconnect customer wiring from Wires No. T1 and T2 in alternator connection box. Check a-c voltage

output at Wire No. T1 and junction of Wires T2. Reading should be ap proximately 125 Volts a-c at no-load and 115-125 Volts a-c under load.

RESULT:- Vol.tage output bad,,

Voltage checks good.

.Continue diagnostic tests

.....Check customer wiring

NOTE

Alternators are factory connected to provide a 120 Volt a-c output

only. Some units may have been reconnected to supply 120/240 Volts a-c. See Page 1.2-3.

TEST 37;- SENSING TRANSFORMER

White Connector Plug

A./-Remove 2 wire nuts that connect

wires No. 11 and 22, between Sensing

Transformer and Voltage Regulator.

Disconnect the wires. Set VOM to ”+DC” and to ”Rxl00" scale, then ze ro the meter. Connect meter test probes across wires No, 11 and 22

from the Sensing Transformer. Meter

needle should swing upscale and indi

cate secondary winding resistance.

See illustration at right.

Winding Wescoil Coiltran

Primary 785 ohms 969 ohms

Secondary 1886 ohms 1438 ohms

Resistance (± 15%)

RESULT;- Secondary winding resistance checks good

Meter needle does not swing upscale

.......

...

Go to Paragraph В

Replace Transformer

B.)- Unplug the white connector plug from its receptacle on the stator

can. Set VOM to ”-t-DC” and to ”RxlO, 000" scale. Zero the meter. Connect one meter test probe to white connector plug Pin No. 3. Connect the re

maining probe to white connector plug Pin No. 5, Meter needle should

swing upscale and indicate PRIMARY winding resistance. See illustration

above right.

2.2-19

RESULT:- Primary windiag rasistance. checks good..Check customer wiring

Primary winding resistance is bad,.......Replace Transformer

NOTE

The Sensing Transformer secondary windings MUST connect to the Voltage Regulator, The primary windings..must connect to the white connector plug. In most cases, primary and secondary wi ndings will be identified when replacing a Transformer. If the windings are not identified, check winding resistance. The winding having the HIGHEST resistance is the SECONDARY winding.

TEST 38:- MAIN CIRCUIT BREAKER

Set VOM to ”+DC" and to "Rxl" scale.

Zero the meter. See illustration at

right. Connect VOM test probes acr oss the Main Rreaker teat points.

Meter needle should swing upscale to

zero with Main Breaker ON, When the

Breaker is set .to OFF, needle should

drop all the way downscale (infinity),

RESULT:- Main Breaker cheeks good.

Main Breaker feeafes bad.

TEST 39:- CHECK ROTOR

A.)-Disconnect the white connect or plug from its receptacle on the stator can. Set VOM to "+DC” and to "Rxl” scale, then zero the met er. Connect the positive (+) meter test probe to white receptacle Pin 4, Connect the common (-) probe to receptacle Pin 1, Meter needle should swing upscale and indicate rotor winding resistance (approxi

mately 15,6 Ohms),

RESULT:- Rotor checks good

Rotor checks bad..

.Continue diagnostic tests

..........Replace Breaker

....

Go to Test 40

,Go to Paragraph B

2.2-20

rotor checks bad in Paragraph A, check Wires No. 1 and 4 for an open or shorted condition. Inspect brushes - replace if cracked, chipp ed or less than 5/16 inch long. Inspect slip rings and clean with fine sandpaper, if necessary. Make sure brushes are making good contact with slip rings. Finally, recheck rotor winding resistance at Pins 1 and 4 of white receptacle as outlined in Paragraph A.

RESULT:- Wires, slip rings and brushes

check good but rotor still

checks bad......................................Replace rotor

Wires, slip rings or brushes

check bad............................Repair, clean or replace

TEST 40:-CHECK FIELD BOOST refe?^to^Section^rr)^°'^'^^^ 6897-4

Unplug the Ignition Module to pre

vent the engine from starting. Al

so unplug the red connector plug from its receptacle on the stator can. Set VOM to ”+DC" and to any

scale that will permit 12 Volts to be read. Connect the positive (+) meter test probe to red connector

plug Pin 5, Connect the negative

(-) test probe to frame ground. Crank the engine - meter needle should swing upscale and indicate approximately 9-12 Volts d-c,

RESULT:- No field boost valtage indicated

Field boost voltage checks good

B,)-Unplug connector plugs from

the Printed Circuit Board and from the red receptacle on stator can. Set VOM to "+DC” and to "Rxl” sca le, then zero the meter. Connect one meter test probe to Pin No, 2 of the printed circuit board conn ector plug. Connect second test probe to Pin No, 5 of the red con

BOTH CONNECTOR PLUGS VIEWED FROM WIRE END

nector plug. Meter needle should

swing all the way upscale to zero.

RESULT:- Meter indicated, zero,

...

Meter did not swing upscale,

..........

....

Continue diagnostic tests

Printed Circuit Board

Connector Plug

Go to Paragraph B

Pin No.2

Red Connector Plug (On Stator Can)

Wire No.4

k -■ Pin No. 5

.Replace printed circuit board .Repair/replace Wire No, 4 or

defective connector plug

2.2-21

TEST 41:-CHECK STATOR

A.)- Set VOM to ”+DC" and to ”Rxl”

scale, then zero the meter. Connect

meter test probes to Pins 1 and 2

of red receptacle on stator can. Me ter needle should swing upscale and

indicate approximately 0,42 Ohms.

RESULT, - Meter needle did not move

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

Replace stator

Checks good................................Go to Paragraph B

B, )- With VOM still set to ”-l-DC” and to ”Rxl” scale, connect meter test

probes to red receptacle Pins 3 and 4, Meter needle should swing up

scale and indicate approximately 0.42 Ohms.

RESULT:- Meter needle did not move

Checks good..-. ....

............ .Go to Paragraph C

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

Replace stator

C. )- Set VOM to ”+DC” and to ”Rxl0,000” scale, then zero the meter. Connect one meter test probe to red receptacle Pin 1 and the second test probe to frame ground. Meter needle should not move. Repeat test with

one test probe connected to red receptacle Pin 3 and the second probe to frame ground. Meter needle should not move,

RESULT:- Meter needle moved upscale

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

..Replace stator

Checks good........................Continue diagnostic tests

2.2-22

SECTION 2.3

BATTERY CHARGE CIRCUIT

CHARRING CURRENT

1,)- Plug the black (-) test lead into the "-10A" jack on the VOM. Plug the red (+) test lead into the "+10A" jack on the meter. Set the meter range switch to ”10 Amps”

(dual position with 10 MA).

2.)-Locate the 15 Amp Fuse inside

the alternator control panel. Co

nnect the red meter test probe to

the Wire 15 terminal on the Fuse

Holder, Connect the black test

probe to the Wire 13 terminal on the Fuse Holder.

TESTS

3.)-Start the alternator. With the engine running, remove the 15

Amp Fuse from its holder. With

the Fuse removed, the alternator should indicate a current output dependent on battery condition.

RESULT:- Ammeter indicates a current output..........Discontinue tests

No current output indicated.,.,

CIRCUIT BREAKER CB-2

Disconnect Wires No, 77 and 78 from

the battery charge circuit breaker (CB-2). Set VOM to ”+DC” and to ”Rxl” scale, then zero the meter. Connect

the meter test probes to the circuit

breaker terminal studs. Meter needle

should swing upscale to zero. If it does not swing upscale, replace the circuit breaker.

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

Continue tests

DIODES D1 ANDD2

A.)- Disconnect Wire No. 78 at the

circuit breaker CB-2, Set the VOM to '*+DC” and to ’’Rxl” scale. Zero the meter. Connect the positive (+)

test probe to Wire No. 78 from the Diode D-2. Connect the common (-) test probe to frame ground. Meter

needle should not move. Set meter

to ”-DC", or reverse the meter test probes. Meter needle should swing

upscale to some mid-scale reading

(approximately 7-12 Ohms).

RESULT:- Diode D-2 tests good...... Reconnect Wire 78,

Diode D-2 tests bad

.....

....

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

go to Paragraph B

.Replace Diode D-2

B.)- Set VOM to ”+DC” and to ”Rxl” scale, then zero the meter. Connect

the positive (+) test probe to the Diode D-1 terminal end. Connect the common (-) test probe to frame ground. Meter needle should not move. Set meter to ”-DC” or reverse the test probes. Meter needle should move

upscale.

RESULT:- Diode D-1 tests good.....

Diode D-1 tests bad.............

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

...........

...Replace Diode D-1

Continue tests

STATOR BATTERY CHARGE WINDINGS

Disconnect Wire 77 from Circuit Break

er CB-2, Unplug the red connector plug from its receptacle on the stator can.

CB-2

Set VOM to "+DC” and to ”Rxl" scale, then zero the meter. Connect one meter test probe to Wire 55 at the Diode D-1

.08 ohm.

Pin 6

terminal. Connect second test probe to Pin 6 of the red receptacle. Meter needle should swing upscale (approxim

ately ,08 Ohm). Repeat test with meter

.08 ohm.

€ 0

0 0

RECEPTACLE

RED

test probe connected to red receptacle Pin 6 and Wire 77 - meter should indi

cate approximately .08 Ohm,

•DIODE D-1

RESULT; Both meter readings were approximately

.08 Ohm

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

Meter needle did not indicate .08 Ohm

2.3-2

..........

Test good

Replace stator

SECTION 2.4

MODEL 6897-4

2.4.1-GENERAL

2.4.1.1-INTRODUCTION

The Model 6897-4 (MC-40) alternator incorporates several new components in its DC control system. The new components replace the printed circu it board used on earlier models. They will improve starting and simpli

fy component testing, removal and replacement. New components are:-

1. )- Choke Pulse Module (CM)

2. )- Control Relay (CR)

3. )- Field Boost Module (FB)

2.4.1.2-CHOKE PULSE MODULE

The Choke Pulse Module performs

several important functions, rel

ated to engine starting. These

functions are:-

1. )-Provides the necessary compo nents for delivery of a pulsing voltage to the automatic choke

solenoid during cranking.

2. )-Provides the required circui try for energizing the fuel lockoff solenoid and (electric) fuel pump during cranking, before the control relay (CR) is energized.

2.4.1.3-CONTROL RELAY (CR)

The Control Relay (CR) is equipped with a pushbutton for manually cl osing the CR contact. The pushbut

ton can be identified by the words

FUEL PUMP on the unit control pan

el. To prime the carburetor prior to cranking the engine, depress the pushbutton. This action will energize the Fuel Lockoff Solenoid open and operate the (electric)

Fuel Pump. After a start, the CR

remains energized to hold the Fuel

Lockoff Solenoid open and operate

the Fuel Pump. (While cranking,

part of the Choke Pulse Module cir

cuit performs the latter function.)

MAIN

BREAKER

® -©

Q 4000 O I MC-40

WATT "

STOP STAUT

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

Control Relay (CR)

2.4-1

2.4.1.4-FIELD BOOST MODULE (FB)

Many alternators rely on residual

or ’’stored" magnetic energy to provide the initial magnetic field around the rotor windings. Residu

al magnetism can be lost due to

shock or physical damage. The MC alternator is equipped with a Field Boost Module (FB) which

supplies battery current to the rotor windings during each start.

2.4.2- CIRCUIT OPERATION

Battery power is available through Wire No. 13, the 15 Amp Fuse, and Wire No. 15 to the Control Relay (CR) contacts. When the push button

(FUEL PUMP) is depressed, the CR contacts close. This completes the 12 Volt DC circuit through Wire No. 14, the Fuel Lockoff Solenoid (FS), Fuel Pump (FP), and the Choke Heater to frame ground. The Fuel Lockoff Solenoid is energized open and the Fuel Pump operates.

2.4-2

2.4.2.2-CRANKING

the 15 Amp Fuse, Wire No. 15, the Starter Contactor (SC), and Wire

No. 17. When the Stop/Stairt Sx<rLtch is set to START position,, the cir

cuit is completed through Wire No. 10 to frame ground. The Starter Contactor (sc) energizes and its contacts close. With the SC contacts closed, several events occur as follows

1, )- Battery power is supplied through Wire No. 91 to the Starter Mo

tor and to frame ground. The engine cranks,

2, )- Battery power is supplied through Wire No. 91, through the Choke

Solenoid (CS), Wire No. 90, and to Pin No. 1 of the Choke Pulse

Module (cm). Solid state components within the CM open and close

this circuit through CM Pin No. 2 and Wire No. 10 to ground, at a rate dependent upon ambient temperature. The Choke Solenoid (CS) is thus pulsed and the automatic choke operates at a rate dependent on ambient temperature,

3, )- Battery power is supplied across the closed SC contacts, through

Wire No. 91, to Pin No, 5 of the Choke Pulse Module (CM), The

circuit is completed within the CM, through Pin No. 3, through Wire No. 14, the Fuel Lockoff Solenoid (FS), the Fuel Pump (FP), Choke Heater and through Wire No, 10 to frame ground. The Choke Heater energizes, the Fuel Lockoff Solenoid (FS) opens, and the Fuel Pump (FP) operates,

4, )- As the engine cranks, the Ignition Stator (IS) supplies a volt

age pulse to the Ignition Module (IM). The Ignition Module in

turn supplies a timed voltage pulse to the Ignition Coil primary

winding. The buildup and collapse of this voltage pulse induces

a voltage into the Ignition Coil secondary winding to fire the

spark plug.

5, )- Battery power is supplied through Wire No, 14 to the Field Boost

(FB) module. A 15 Ohm, 10 Watt resistor reduces this voltage and

a Diode (D3) ensures correct polarity. The reduced voltage is

delivered to the rotor windings via Wire No. 4, 243

2.4.2.3- RUNNING

Releasing the Stop/Start Switch to NEUTRAL opens the DC circuit from

the battery. Wire No. 13, 15 Amp Fuse, Wire No. 15, Starter Contactor

(sc), and Wire No. 17. The SC de-energizes and its contacts open to

terminate cranking and choke operation. The Control Relay (CR) is held energized by AC output from the Battery Charge Windings, and the CR contacts close. Battery power is delivered through the closed CR cont acts to the Fuel Pump (FP), Fuel Lockoff Solenoid (FS), and Choke Heat er to maintain engine operation. The Ignition System continues to func tion and Field Boost current is still available.

2.4.2.4-SHUTDOWN

2.4-4

When the Stop/Start Switch is set to STOP, Ignition Stator (IS) output

from Wire No. 25, Ignition Module (IM) Pin No. 3, Wire No. 25 to the

Terminal Block and Wire No. 20 is delivered to frame ground. Ignition

terminates and the engine shuts down. The Control Relay de-energizes and its contacts open to close the Fuel Lockoff Solenoid (FS) and ter

minate Fuel Pump (FP) operation,

2.4.3- DIAGNOSTIC TESTS

2.4.3.1- CHOKE PULSE MODULE

METHOD 1:- Install a known good Choke Pulse Module, Crank engine,

RESULT:- Choke operates normally...........Replace Choke Pulse Module

Engine starts.

Choke does not function and/or

....

Continue Diagnostic Tests,

no start Section 2,1

METHOD 2:- A.)-

Unplug Choke Pulse Module, Set VOM to "+DC” and to ”50V." scale. Connect positive (+) meter test probe to Module receptacle Pin No,

1, common (-) test probe to frame

Choke Pulse Module

ground. Crank engine. Meter should indicate 9-12 Volts DC. This is

the input voltage to the Choke Pu lse Module,

Choke Pulse

B, )-Plug Choke Pulse Module into

its receptacle. Set VOM to ”+DC"

Module Receptacle-

Ignition Module ReceptacI

and to "50V,” scale. From bottom

of receptacle, connect positive (+) meter test probe into receptacle Pin No. 1 and common (-) test probe

to frame ground. Crank engine. The meter should indicate a pulsing

voltage and choke solenoid should

pulse. C. )-Plug Choke Pulse Module into its receptacle. Set VOM to "+DC" and

to '’50V,” scale. From bottom of Module receptacle, connect positive meter test probe to receptacle Pin No. 3, Connect common (-) test pr

obe to frame ground. Crank engine. Meter should indicate approximate

ly 12 Volts DC. RESULTS:-All tests were good..,.Continue diagnostic tests. Section 2.1

Test A checked bad

....

Check Wire No. 90 between receptacle

and Choke Solenoid, Choke Solenoid,

Wire No, 91 between Choke Solenoid and

Starter Solenoid (SC), Starter Solenoid (SC)

Test B checked bad

....

Replace Choke Pulse Module (CM)

Test C checked bad,,,,.Replace Choke Pulse Module (CM)

2.4-5

2.4.3.2- CONTROL RELAY (CR)

Refer to 2.4.1,3 and 2,4.2, this Section, If engine starts and then shuts down, the problem may be caused by the Control Relay (CR). Pro ceed as follows to check the Control Relay

A. )-With unit battery properly connected, depress Fuel Pump button.

The Fuel Lockoff Solenoid should open and Fuel Pump should operate.

RESULT :-Checks good,...........................

Checks bad

.........

Check 15 Amp Fuse and priming circuit -

Go to Paragraph B

See 2.4.2.1, PRIMING

B. )-Crank engine while holding Fuel Pump button depressed. Continue

to hold button in after engine starts, then release.

RESULT:-Engine starts and runs normally,

shuts down after button is rel-

.........

Go to Paragraph C

eased

No change - engine starts then,..Continue Diagnostic Tests,

shuts down as before

C. )-Set VOM to "AC", Connect one me

ter test probe to Pin No. 7 of the

Section 2,1

CONTROL RELAY RECEPTACLE

VIEWED FROM WIRE END

CR receptacle. Connect remaining

test probe to receptacle Pin B, then crank engine. Meter should indicate approximately 10-12 Volts AC,

RESULT:- Checks good Checks bad

....

Check wires 15 and 77-

.....

Replace CR

If wires check good, replace stator assembly

2.4.3.3- FIELD BOOST MODULE

A.)-Unplug red receptacle from its receptacle on stator can. Set VOM

to "-HDC" and to any scale that will permit 12 Volts to be read. Connect the positive (+) meter test probe to red connector plug Pin No,

5, Connect the common (-) probe to frame ground. Depress the Fuel Pump button - meter should indicate app roximately 9-12 Volts DC.

RESULT:-Checks bad,.....Go to Para

graph B

Checks good

....

Continue

tests. Section

2.1

2.4-6

B,)-Set VOM to ”+DC” and to any

scale that will permit 12 Volts to be read. Connect the positi ve meter test probe to the Wire

No. 4 connection at Field Boost

Module, Connect the common (-)

test probe to frame ground. De press the Fuel Pump button- the

meter should indicate 9-12 Volts

DC.

RESULT;-No voltage indicated........................Go to Paragraph C

Voltage is indicated, but none

....

.Repair/replace Wire No. 4

in Paragraph A between red receptacle and Field

Boost Module

C,)-Set VOM to ”+DC” and to any scale that will permit 12 Volts DC to be read. Connect the positive (+) meter test probe to the Wire No. 14

connection at Field Boost Module, Connect the common (-) test probe to frame ground. Depress the Fuel Pump button. Meter needle should iftdicate 9-12 Volts DC.

RESULT:-Normal DC voltage indicated

but not in Paragraph B

No voltage indicated

..........Check Wire No. 14 between

.......

Replace Field Boost Module

the Field Boost Module and the

Control Relay (CR)

2.4-7

PART III

DISASSEMBLY &

Section 3.1

3.1.1

3.1.2

3.1.3

Section 3.2

3.2.1

3.2.2

3.2.3

Section 3.3

3.3.1

'3.3.2

3.3.3

BLOWER SHROUD SECTION

Disassembly

Inspection and Repair

Reassembly

ALTERNATOR SECTION Disassembly

Inspection and Repair

Reassembly

ENGINE SECTION

Disassembly

Inspection and Repair

Reassembly

REPAIR

3.1.1-D1SASSEM<^LY

SECTION 3.1

BLOWER SHROUD SECTION

3.1 .1 .1 -IT.sp R 5/16 Inch nut driver to remove screws and flat washers Chat retain blower shroud end pan el. Remove end panel.

3.1.1.3-Insert a screwdriver into a

cooling air slot of engine adapter

housing to prevent ring gear from

Cuming.

3.1.1.2-Reiiiuve philllps head screws

that retain blower inlet ring. Rem

ove blower inlet ring.

3.1.1.4-While preventing ring gear from turning, remove the special M-

14 hex nut that retains the blower fan hub to engine Caper shaft.

3.1.1.5-Tnstall three 5/16-24 bolts

into threaded holes of blower fan

huh. Install a puller as shoi^n at

right and pull blower fan and blow er fan hub free of engine taper shaft.

3.1-1

2#_l_Ll2_6-Use a lO nim \^пгRт^ch to rem

ove blower, scroll bolts nearest the pngine taper shaft. The bolt at low

er right comer of blower scroll ex

tends through the shrouding and is retained by a lock washer, flatwasher and hex nut on shroud exterior.

Use a 7/16 inch wrench to remove the bolt and nut.

3.1.1,7-RemoVP four MlO bolts and

four lockwashers that retain Che cy linder head cover. Remove cylinder

head cover.

Wmm

3.1.1.8-Remove two M8 socket head 3.1.1.9-Remove bolt and washer Chat

capscrews that retain the exhaust pipe to engine.

retains housing and exhaust pipe support to vibration dampener.

3.1,1,lU-Use a nut driver to remove screws that retain blower housing

upper ends to engine. Remove blower

housing.

3.1-2

3.1.2-INSPECTION AND REPAIR

Clean and degrease all components, including sheet metal* Inspect all parts as follows

1*)- Carefully check all sheet metal for cracks or other damage. Repair

or replace damaged sheet metal*

2. )- Inspect all weld nuts.

3. )- Check foam rubber gaskets on blower shroud sheet metal* Replace all damaged strips.

4. )- Inspect blower fan for cracks or other damage. Replace, if damaged.

5. )- Inspect blower fan hub. Replace, if cracked or damaged or if key way is worn* Also check key and key^^ay on engine taper shaft*

3.1.3-REASSEMBLY

3.1.3.1-Retain blower shroud and 3.1.3.2-Retain blower shroud at

blower scroll to cylinder block with two M5 X 10 mm capscrews and

Inckwashers. Tighten capscrews to

90-110 inch-pounds.

3.1.3.3-With exhaust pipe u-bolt and housing and exhaust pipe sup port loosely retained by 2 hex nuts, lockwashers and flatwashers,

retain housing and exhaust pip« support to engine base and vibrat ion damper.

both sides of cylinder block

with M6 X 15 mm long capscrews, Inckwashers and flatwashers.

3.1-3

3.1» 3,4-Loosoly retain blower hou sing support to opposite vibration

damper with capscrew, lockwasher

and flatwasher.

3,1,3,^"Retain blower housing and

scroll to blower housing support

(installed in previous step) ^^th b-20 X ^ inch long bolt and flaLwasher and a hex nut, flatwasher and lockwasher. Tighten the hex

nut. Finally, tighten all bolts that

thread into the vlhratlon dampers.

3,1,3,6-Slide exhaust pipe down

through blower housing ^nd through

exhaust pipe u-bolt. Install exha

ust flange gasket. Retain exhaust pipe to exhaust flange with an M8

X 50 ram long and an M8 x 20 mm long

socket head capscrew and lockwash-

prs.

3,1,3,8"Retaln cylinder head cover

with four MlO X 20 mill long bolts

and lockwashers. Tighten bolts to 12 foot-pounds. TnsLall all No. 10-

32 screws that retain head cover to

blower housing.

3,1,3,7"Tightcn exhaust pipe u-bolt

hex niiLs,

3.1-4

3^1,3>9-Align keyway in blower fan

hub wlCh drive key on engine shaft.

Install blower fan over engine

shaft. Make sxire drive key and key

way are engaged. Install special M-

14 hex nut and flatwasher. Prevent

crankshaft from turning, then torq

ue hex nut to 50-55 foot-pounds.

3.It 3#11-Install blower shroud end panel. Retain with No. 10-32 screws and flatwasherst

3.1.3.lO-jnstall inlet ring as

sho\smi. Retain w1 th No. 6-32 x

3/8 inch long screws and lock-

washers.

3.1-5

3.2.1-DISASSEMBLY

SECTION 3.2

ALTERNATOR SECTION

3#2»1«1-At the terminal strip, dis

connect Che Wire No. 20 chat comes

Truiu the low oil level shutdown sw

itch.

3.2.1.3“Remove 4 screws that retain

irront panel. Remove front panel.

3.2.1.2“Loo3en oil line clamp at oil make-up pump. Slide clamp down hose, then disconnect hose from

pump fitting.

3,2,1.6-Unplug the red connector

plug from Its stator can recepLacle,

Also remove ground wire, retained

by panel divider screw.

3.2.1.5-Remove screws that retain

rear panel. Remove rear panel.

3.2.1.6-Remove end panel.

3.2-1

3.2,1,7~St:raighCpn brush holdei'

locking tangs on bearing carrier, Kemove brush holder from carrier.

Remove brush leads from brushes and remove brush holder and brus

hes .

3,2.1,9-Remove two bottom stator 3,2.1,10-Remove 6 screws that ret-

bolts and stator bolt bar.

3,2,1»d-Remove al temator support to vibration dampener bolts.

aln bearing carrier to stator can, Remove bearing carrier, using a

puller.

3,2,1.11-Ramove 2 upper stator

bolts and stator holt bar.

3.2-2

3,2.1.12-RGmove panel divider. The stator can may now be removed as

well.

3»2., 1« 13-Remove starter cable at

the starter terminal.

3.2.1.14-Cur Wires No. 8 and 25 that go to the ignition stator.

3.2.1.15-At the terminal strip,

disconnect the wire from the fuel

lockoff solenoid.

3.2.1.l7-Rcmovc bolts, nuts and washers that retain the adapter casting. Remove carburetor to intake manifold nuts, then rem ove adapter casting.

3.2.1.19-Use rotor removal kit

to remove rotor. (See Section

1.3, SPECIAL TOOLS.) Use the 5/16-24 tap from kit to cut threads in totor as shown at

right.

3.2.1.16-Remove fuel Line at carb

uretor. Carburetor to intake luaui-

fold iiuLs may also be loosened at this time. These nuts will be cionipletely rpTTioved prior to removal

of the adapter casting (Step 3.2.

1.17).

3.2.1.18-Remove -rotor bolt.

3.2-3

3,2,1,20~SelQcc a stud from the

kit that is long enough so that, when the stud is threaded into the engine crankshaft, the slot ted end of the stud will extend

approximately Inch into the

rotor shaft. Thread the stud in to the engine crankshaft.

3,2,1,22-Remove the ignition stat

or.

3,2,1,21-Thread the 5/16-24 bolt

(included with rotor removal kit) into the rotor shaft until It Is fiinnly seated against the stud.

Tighten the bolt against the stud

and tap the bolt head with a mal let, Continue tightening and cap

ping until rotor is free. Remove Che rotor and fan assembly.

3.2.2-INSPECTION AND REPAIR

3,2,2,1- GENERAL Inspect wiring for pinching, obvious damage, defective insulation.

Clean all parts and Inspect for-obvious damage, cracks, etc. Check

connector plugs and receptacles for damage, pins pushed out of sockets, etc. Repair or replace damaged, defective parts as requir*

ed.

3.2-4

3,2,2,2- BRUSH HOLDER AND BRUSHES

3.2.2.3- BEARING CARRIER

Replace brush holder if cracked or otherwise damaged. Replace brushes if cracked, chipped or less than

5/16 inch long.

3.2>2.4- STATOR Inspect closely for damage. Use an

insulation breakdown tester and test for breakdown under load. Follow the

tester manufacturer's instmactions carefully. See 1.1.3, ELECTRICAL TEST SPECIFICATIONS.

Once removed, the bearing carrier

should not be re-used. Replace the

bearing carrier during reassembly.

3.2.2.5- ROTOR

Inspect closely for damage. Use an insulation breakdown tester to test for breakdown under load. Follow the

tester manufacturer's instructions carefully. See 1.1.3, ELECTRICAL TEST SPECIFICATIONS.

3.2.3- REASSEMBLY

3,2.3,1-During reassembly, torque fasteners as specified in Section 1.1.4,

TORQUE SPECIFICATIONS (GENERAL) or 1.1.5, TORQUE SPECIFICATIONS (SPECIAL),

as applicable. Do not attempt to re-use worn, defective or damaged parts.

The bearing carrier should not be re-used once it has been removed.

3.2-5

3> 2,3« 2"Ignition scacor mouncing

holes are offset to make improper

Installation difficult. Install the ignition stator and retain

with No. 10-32 X 3/8 inch screws.

3.2.3.3-Isnition stator wires (No.

8 and 25) were cut during disassem bly. Tf wires are Coo short for pr oper splicing after unit is assemb

led, additional wiring lengths must be added at this time. Above, knife

edge connectors were used to add

the additional wire length. Heat

shrink tubing was then installed and

shrunk over the coimecLors. (NOTF:Some later production units may be

equipped with quick disconnects at

these wires for ease of maintenance.)

3.2.3.4-Pull both ignition stator

wires through the hole provided in Che engine gear cover. Retain \i7ires

flush against gear cover with RTV-

103.

3.2.3« 6-Install rotor. Make sure

key and keyway are engaged. In

stall rotor bolt, lockwasher and 2 flatwashers. Tighten rotor bolt,

making sure rotor pulls in as the bolt is tightened. When rotor is

tight and will pull in no further, loosen rotor bolt. Then tighten bolt Co 15-17 foot-pounds.

3.2-6

3.2.3.5-Inspect Woodruff key and

keyway on engine Caper shaft and

rotor. Replace key if damaged or worn. Install key into keyway on engine taper shaft.

3¿_2jj_3_2_7-Align adapter casting with

bolt holes in engine gear cover.

Install casting, making sure the carburetor intake manifold studs are aligned with carburetor. At

the lower right comer of casting,

retain wi Lh a x 2'^ bolt \d.th square nut. Also retain with

two 'i/ló-lS X 2^” bolts, lockwashers and hex nuts. Upper left corn er of casting will be retained by a 5/16-18 X 4" bolt and hex nut, which will aslo retain the starter.

3.2.3.8-Iastall a new carburetor

to intake manifold gasket. Retain carburetor to intake manifold with two -^-20 NyLok nuts.

3.2.3.9-MechanicaI Fuel Pump Only: Install fuel pump, inlet filter, solenoid shutoff valvp, interconn ecting hoses and clamps. Retain the fuel pump with two M6 x 18 mm sock et head capscrews and lockwashers.

Tighten capscrews to 25-30 inch

pounds.

3.2.3.10-The fuel pump to carburet

or fuel line contains a filter

screen. Install clamps over fuel line. Then connect line to carbur etor inlet fitting and fuel pump

outlet fitting. Retain line with clamps.

3.2-7

1.2*3, ll-CoiuifeicL Wire No, 14 (the

longest vTire) from the fuel lockoff solenoid Co Lhe termtnal strip. Refer to appropriate wiring diagram

for wiring connections.

3.2,3.12-wlres No. 8 and 25 from the ignition stator were cut during disassembly, (NOTE;-Some later pro

duction units may have a quick dis connect on these wires.) If wires

were cut, strip wire ends and inst all a knife edge coiiuecLor.

3.2.3,13-Install heat shrink tubing

over Che connectors on Wires 8 and

25.

3.2-8

3,2.3.14-install starter bolt. The upper starter holt (5/16-18 x 4") passes through starter, engine

gear cover and adapter casting. Lower starter bolt is a 5/16-18 x 1'* socket

head capscrew. Tighten starter bolts,

then torque adapter casting bolts (in cluding 4 inch long starter bolt) to 120 inch pounds» Finally, install the starter cable and retain with hex nut

and lockwasher.

3.2.3.15-Careful 1v align stator and

install over rotor.

n pane.l dividpr to sta

tor can with two taptite screws. The ground wire (No. 10) previously dis connected from Stop/Start switch ter-

minal connects to one of these screws. lower stator bolts are install-

3.Z.ii. 1 / -Install upper stator bolt bar. Install both upper stator bolts. Only the two upper stator bolts have a spac

er. Bolts can be tightened later, after

3.2.3.18-Apply a small amount of Loc-

Tite to rotor bearing outer diameter.

Install a new bearing carrier. Retain

3.2.3»19-Install alternator supp

ort onto vibration dampeners. Re tain with two 3/8-16 X 3/4” bolts

carrier to stator can with four No. 10-and iockwashers. Install the low-

32 X 3/8" Taptite screws. er stator holt bar. Install two

lower stator bolts with lockwashers. Tighten all 4 stator bolts.

Make sure stator can is flush ag

ainst adapter casting, then tighten all 4 stator bolts to 80100 inch pounds.

3.2-9

3.2.3.20-Connecc 2 red wires (No. 3,2.3.21-Sllde brush holder lock-

A) to brush that will he nearest

Che rotor bearing. Retain \^th a No, 6-32 Sims screw and 2 exter nal lockwashero. Connect 2 ground wires (No. 10) to remaining brush with Sims screw and 2 lockwashers

ing grooves over bearing carrier locking tangs. Make sure brushes contact slip rings properly. Bend

bearing carrier locking tangs to

retain brush holder.

3.2.3.22-Retaln brush ground wire (No. 10) to heat sink with heat

sink retaining screw.

3.2-10

3.2.3.23-Install end panel. Ret

ain to stator can with two No. 10-

32 X 3/R” Taptite screws. (A small

grounding lug is also retained by one of these screws.)

3« 2» 3,24-Install rpar panel with voltage regulator. Connect read and white connector plugs into

their receptacles. Install front panel• Connect ground wire (No.

10) to center terminal of stop/ start switch.

3.2.3,25-lnstall oil make-up tank

with piimp. Connect oil lines to

pump and probe, retain with clamps.

Connect Wire No. 20 from low oil

level shutdown switch to terminal strip (see appropriate wiring dia gram) , Connect ground wire from low oil level shutdown switch and from fuel lockoff solenoid to the tapped hole on adapter casting, along with fuel lockoff solenoid clamp

3,2-ll

3.3.1- DISASSEMBLY

SECTION 3.3

ENGINE SECTION

3.3.1. l-Dlsconnect. governor spring from governor adjusting screw. Loo sen governor arm'clamp bole and re

move governor arm from governor

shaft.

3.3.1.3-Ramovp engine from alterna tor slide pan.

1 f

3.3.1.2-Remove spark plug.

3.3.1.4-Remove breather assembly.

i i I

3.1.5-Remove intake manifold elbow. 3.1.1_._6-Remove engine cowling.

3.3-1

3,3*1« 7-Remove 8 cylinder head uuts.

Remove cylinder head and head gasket:«

3.3.1.8-Intake and exhausC valves are shown in a sectional view ab ove. Valve springs are retained

Co valve stems by valve retainers and a roller pin. Keep valve parts together as a set. Intake valve is identified by the letter ”1” on

3,3«l,9~Use valve spring compressor Co compress valve springs. Then re

move roller pin from valve stem.

Remove compressor, Chen remove valve

springs, spring rpLaine.rs and valves.

3.3.1.11-Remove thrust washer from

end or cam shaft.

3.3-2

3,3.1»10-Drain engine oil. Remove

all bolts chat retain engine bear

ing cover. Rotate crankshaft to

place its keyx^ay at 12:00 position

(top dead center of piston stroke). Install screws into ignition stator screw holes. Use these screws and a

puller Co remove bearing cover.

3,3,l.l2-RGmovc governor slider from 3.3.1.13-Remove cam shaft and valve

end of cam shaft. tappets*

3* 3*1*14-Bend lock Cab ends away from connecting rod bolt heads. Remove the

connecting rod bolts, lock tab, oil

splasher and connecting rod lower half.

Push piston and connecting rod up

through cylinder and remove. Remove

crankshaft.

3.3.1.16-It is not necessary to

remove bearings unless replace-

menc is necessary. Bearings

must be pressed out of cylinder block.

3.3.1.15-Remove oil stopper,

3.3-3

3.3.1.17-Remove governor shafL

retaining clip and governor shaft.

3.3.1.18-Remove oil stopper from

engine bearing cover.

3.3.1.19-Remove bolts that ret

ain counterbalance cover.

3.3.1.21-Remove counterbalance

assembly.

3.3-A

3.3.1.20-InstaII a bolt into the threaded hole at top of counter

balance cover. Tighten bolt aga

inst counterbalance shaft until cover is free of shaft, then i*e-

move cover.

3.3.1.22-$him washers are used at bearing cover end of crankshaft to establish crankshaft end play.

Check uumber of shims- during re assembly, the same number of shims

must he used.

3.3.2- INSPECTION AND REPAIR

3.3.2.1- CYLINDER BLOCK

Replace cylinder block i£:-

a. )-Fins are broken or cracked

b. )-Head mounting surface is warped

c. )-Cylinder inner diameter is greater than 0,5 mm oversize.

If cylinder is to be rebored, first determine whether to bore 0,25 mm

or 0,50 mm oversize. Use any standard commercial hone of a suitable

size. Chuck the hone in a drill press having about a 600 rpm speed.

Use standard boring procedures.

Valve seats require grinding only if pitted or scored. If seats are not pitted or scored, lapping will provide a satisfactory valve seat.

Valves must be lapped to seats when seats are reground,

3.3.2.2- ENGINE GEAR COVER

Clean and degrease engine gear cover. Replace if cracked, warped, or damaged,

3.3.2.3- CAMSHAFT

Clean camshaft in non-flammable

solvent and blow dry. Replace a

camshaft that shows signs of wear or scoring. If a damaged camshaft gear is replaced, also

replace the mating crankshaft gear. If keyways are damaged or worn, replace camshaft. Inspect keys, replace any that are dam aged or worn excessively. Repl ace flyweight or governor shaft if damaged.

3.3.2.4-CRANK SHAFT

Replace crankshaft if:-

a. )- Damaged threads can’t be dressed

b. )- Bearing surfaces are worn, scratched or damaged

c. )- Flat spots have developed d. )- Crankshaft is bent - NEVER TRY TO STRAIGHTEN A BENT CRANKSHAFT e. )- Crankpin is out-of-round more than 0,002 inch

When installing a crankshaft, always lubricate bearing surfaces. If the

camshaft drive gear on crankshaft is replaced, replace the mating cam shaft gear as well. The crankshaft must be shimmed during assembly to

establish an end play of 0,0039 to 0,0118 inch.

3,3-5

measure piston

Piston diameter

3.067”-3.068”

3.3.2.5-PISTON

Clean carbon from piston ring gro oves, as well as from upper cylinder

bore and head» Check piston dimensi

Check for proper width of compression

and oil ring grooves on piston. See illustration above.

ons, as shown above. Replacement pi stons are available in 3 sizes standard, 0,25 mm oversize and 0.50

mm oversize.

3.3.2.6- RINGS

Replace rings in sets. During installation ring gaps must be staggered, Before installing new rings, deglaze cylinder walls thoroughly with

fine emery cloth and clean thoroughly. Rings are available in standard size, as well as oversize to match the oversize pistons that are avail

able.

___

_________________________

Check for proper clearance of

compression and oil control rings in piston grooves. See illustration at right.

3.3-6

CTLINCW

PISTON

,pi3TON Ring

Check ring gaps on worn rings to determine if rings should be re

placed. Check gaps on new rings

to determine if cylinder should

be rebored. To check ring gap,

square the ring in the cylinder

bore as shown above.

After squaring the ring in bore, use feeler gauge to check ring

gap.

3.3.2J-VALVES

Intake.and exhaust valves are NOT identical - intake valves are id entified by the letter ”1”, exhaust valves by an "E**.

Clean valve parts in iion-Clainmahle solvent. Remove carbon from valves. Replace distorted or damaged valves. If valves are useable, they may be ground to a 45 degree angle. When new or re-ground valves are to be

installed, lap them to ensue a gas tight fit. Lap valves as follows

1. Coat valve face sparingly with a fine grade of valve grinding comp ound.

2. Rotate valve on valve seat. Lift valve from seat every 8-10 strokes to keep compound equalized on surface of valve seat.

3. Continue lapping until both the valve and seat has a smooth surf ace. Clean thoroughly to remove all traces of lapping compound. Dry thoroughly.

To obtain correct valve tappet clearance, grind ends of valve stems

off squarely. Use a V-block to hold valve stem square to grinding wheel. After grinding, check for proper clearance as follows

3.3-7

1. )- Rotate crankshaft until piston is at top dead center (TlX:) of its compression stroke.

2. )- Insert valves in their guides and hold them firmly on their seats.

3. )- Chock clearance with feeler gauge« Use a metric feeler gauge be

tween valve .stem and tappet. Correct clearance is 0.1 mm plus 0.05

mm. minus 0.

i)fcCTIUW 3.3.3- REASSEMBLY

3« 3« 3.1-Tiista11 counterbalance as

sembly over its shaft in engine gear cover.

3.3.3.3-Install oil stopper into gear cover. Tighten bolts to 90110 inch-pounds.

3.3.3.2-InstaIl counterbalance co ver. Retain with 4 bolts and lockwashers. Tighten bolts to 90-110 inch-pounds.

3. 3. 3.4-Instan governor shaft as senbly. Retain with spring clip.

3.3.3.5-Install oil stopper into cylinder block, lighten bolts to 90-110 inch-pounds.

3.3-8

3# 3# 3# 6-Install crankshaft end play shims. Install crankshaft. Use care not to damage oil seal and bearing#

3# 3# 3« 7-Install rings onto piston#

Ring end gaps should be staggered.

See Section 3.3.2, INSPECTION AND REPAIR, for proper ring locations

In piston grooves. Slide conuectiiig rod with piston installed do^^ through cylinder until rings contact top of cylinder block. Then use ring compressor to compress rings Into piston grooves. With rings compress ed, tap piston into cylinder. While

tapping, align connecting rod with

crankshaft. When rings are engaged by cylinder, remove ring compressor.

3* 3« 3« 8-Connecting rod and connect

ing rod cap are a matched set and

must be replaced as a set. Mark on

cap (see above) must align with id

entical mark on connecting rod dur ing installation#

3.3.3.9-Lubricate bearing surfaces

of connecting rod and cap. Install connecting rod cap, oil splasher, and lock tab onto connecting rod. Retain with connecting rod bolts.

Use torque wrench and tighten bolts

to 18 - 22 foot-pounds. Bend ends of lock tab over bolt heads.

3.3-9

3.3«3>lO-TnsLa11 tappets*

3.3« 3*11-Install cam shaft* Be

careful not to damage bearing and oil seal* Timing mark on valley of crankshaft gear must align

\-ri-th timing mark on tooth of caiii-

shafL gear*

3*3*3*12-InsCall thrust washer

over end of camshaft.

3.3» 3.14-Install one of the long er bolts that retained the engine gear cover into the counterbalan ce alignment hole in gear cover*

Rotate counterbalance while thre

ading bolt into alignment hole.

When holt engages hole in count

erbalance and counterbalance vd.ll

not rotate, tighten bolt no furth

er*

3.3-10

3* 3* 3*13-Bcfore the engine gear

cover can be installed, crank

shaft must be tui.*ned to place its keyway at 12:00 position (top dead center of piston)*

3» .1, 3« 1 5-Insfa 11 a new gear cover

gasket*

3.3* 3*17-Install the correct

bolt and fiat washer into count

erbalance alignment hole* USE

THE COEUIECT BOLT - if bolt is Coo

long, dainagp to counterbalance

will result.

3.3.3*16-Align dowel pin on cyl'

inder block with dowel pin hole on engine gear cover. Install gear cover. When cover is flush against cylinder block, remove bolt from counterbalance align-

ment hole.

3.3.3.18-Retaln engine gear cover

to cyiinder block with bolts and

lockwashers. Tighten all bolts to 00-110 inch-pounds.

3,3,3*19-Tnstall upper and lower valve spring retainers over ends of valve springs. Keep intake and

exhaust valve parts together as a set. See illustration for correct

retainer locations.

3.3-11

3« 3> 3» 20-Install springs and ret

ainers over tappets. Intake valve

is identified by the letter ”1",

exhaust valve by an Slide

both velves dovzn through valve

guides, retainers and springs.

3.3.3.21-Compress valve springs,

using a spring compressor. Then

instali roil pin through hole in valve stem. Remove compressor and make sure roll pin is locked in place by lower valve spring retainer.

•:4 '

'i-

3.3.3.22-Install a new cylinder head gasket. Install cylinder head. Location of 4 longer stud nuts and torque sequence are

shown in illustration.

3. 3. 3. 24-Install cowling,

3.3-12

3.3.3.23-Tlghten head nuts Co 22 29 foot-pounds in sequence shown

in previous illustration.

3.3.3> 25-InsCall new intake mani fold elbow gasket- Install Intake

manifold elbow.

3,3-3,26-Instail spark plug. Cap

should he set to O.Ol^ Inch. Tor

que spark plug to 18-22 foot

pounds .

3.3.3.27-lnstall breather assembly.

Tighten bolts to 90-110 inch-pounds

3«3#3.28-Install engine onto alter

nator slide pan.

3.3-13

Generac Power Systems MC ALTERNATOR User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

DIAGNOSTIC REPAIR MANUAL

SPECIFICATIONS

SPECIAL TOOLS

PART II

TROUBLE DIAGNOSIS

DIAGNOSTIC FLOW CHARTS

BATTERY CHARGE CIRCUIT

MODEL 6897-4

PART III

DISASSEMBLY &