1998 ISUZU TROOPER Crankshaft

ABBREVIATIONS CHARTS
LIST OF AUTOMOTIVE ABBREVIATIONS WHICH MAY BE USED IN THIS MANUAL
A Ð Ampere(s)
ABS Ð Antilock Brake System
A/C Ð Air Conditioning
ACCEL Ð Accelerator
ACC Ð Accessary
Adj Ð Adjust
A/F Ð Air Fuel Ratio
AIR Ð Air Injection Reaction System
ALDL Ð Assembly Line Diagnostic Link
Alt Ð Altitude
AMP Ð Ampere(s)
ANT Ð Antenna
APS Ð Absolute Pressure Sensor
ASM Ð Assembly
A/T Ð Automatic Transmission/Transaxle
ATDC Ð After Top Dead Center
Auth Ð Authority
Auto Ð Automatic
BARO Ð Barometic
Bat Ð Battery
Bat+ Ð Battery Positive Terminal
Bbl Ð Barrel
BCM Ð Body Control Module
BHP Ð Brake Horsepower
BP Ð Back Pressure
BTDC Ð Before Top Dead Center
¡C ÐDegrees Celsius
Cat. Conv. Ð Catalytic Converter
cc Ð Cubic Centimeter
CCC Ð Computer Command Control
CCOT Ð Cycling Clutch Orifice Tube
CCP Ð Controlled Canister Purge
CID Ð Cubic Inch Displacement
CL Ð Closed Loop
CLCC Ð Closed Loop Carburetor Control
CO Ð Carbon Monoxide
Coax Ð Coaxial
Conn Ð Connector
Conv Ð Converter
CP Ð Canister Purge
CPS Ð Central Power Supply
Crank Ð Crankshaft
CTS Ð Coolant Temperature Sensor
Cu.In. Ð Cubic Inch
CV Ð Constant Velocity
Cyl Ð Cylinder(s)
C
3I Ð Computer Controlled Coil Ignition
DBM Ð Dual Bed Monolith
Diff Ð Differential
DIS Ð Direct Ignition System
Dist ÐDistributor
DOHC Ð Double Overhead Camshaft
DVM Ð Digital Voltmeter (10 meg.)
DVOM Ð Digital Volt Ohmmeter
DVDV Ð Differential Vacuum Delay Valve
EAC ÐElectric Air Control
EAS Ð Electric Air Switching
EBCM Ð Electronic Brake Control Module
ECC Ð Electronic Climate Control
ECM Ð Electronic Control Module
ECU Ð Electronic Control Unit
Ð Engine Calibration Unit (PROM)
EECS Ð Evaporative Emission Control System
EFE Ð Early Fuel Evaporation
EFI Ð Electronic Fuel Injection
EGR Ð Exhaust Gas Recirculation
EGR/TVS Ð Exhaust Gas Recirculation/Thermostatic
Vacuum Switch
ELC Ð Electronic Level Control
ESC Ð Electronic Spark Control
EST Ð Electronic Spark Control
ETR Ð Electronically Tuned Receiver
EVRV Ð Electronic Vacuum Regulator Valve (EGR)
Exh Ð Exhaust
¡F Ð Degrees Fahrenheit
FF Ð Front Drive Front Engine
FL Ð Fusible Link
FLW Ð Fusible Link Wire
FRT ÐFront
FWD Ð Front Wheel Drive
4WD Ð Four Wheel Drive
4x4 Ð Four Wheel Drive
4 A/T Ð Four Speed Automatic Transmission/Transaxle
Gal Ð Gallon
Gen Ð Generator
Gov Ð Governor
g Ð Gram
Harn Ð Harness
HC Ð Hydrocarbons
HD ÐHeavy Duty
HEI Ð High Energy Ignition
Hg Ð Mercury
HiAlt Ð High Altitude
HVAC Ð Heater-Vent-Air Conditioning
IAC Ð Idle Air Control
IC Ð Integrated Circuit
ID Ð Identification
Ð Inside Diameter
IDI Ð Integrated Direct Ignition
IGN Ð Ignition
ILC Ð Idle Load Compensator
INJ ÐInjection
IP Ð Instrument Panel
IPC Ð Instrument Panel Cluster
INT Ð Intake
J/B Ð Junction Block
km Ð Kilometers
km/h Ð Kilometer per Hour
kPa Ð KiloPascals
KV Ð Kilovolts (thousands of volts)
KW Ð Kilowatts
0AÐ12 GENERAL INFORMATION

1B Ð 24 AIR CONDITIONING
3
4
2
7 86 1
5
4. Remove serpentine belt.
·Move serpentine belt tensioner to loose side using
wrench then remove serpentine belt.
5. Disconnect refrigerant line connector.
·When removing the line connector, the connecting
part should immediately be plugged or capped to
prevent foreign matter from being mixed into the
line
6. Remove compressor.
Installation
1) Install compressor.
·Tighten the compressor fixing bolts to the specified
torque.
Compressor Fixing Torque Nám (kgám / lbáft)
19 (1.9 / 14)
2) Connect refrigerant line connector.
·Tighten the refrigerant line connector fixing bolts
to the specified torque
Refrigerant Line Bolt Torque Nám (kgám / lbáft)
15 (1.5 / 11)
·O-rings cannot be reused. Always replace with new
ones.
·Be sure to apply new compressor oil to the O-rings
when connecting refrigerant lines.
3) Install serpentine belt.
·Move serpentine belt tensioner to loose side using
wrench, then install serpentine belt to normal
position.
850RY00001
Legend
(1) Tensioner
(2) Idle Pulley
(3) Cooling Fun Pulley
(4) Serpentine Belt
(5) Power Steering Oil Pump
(6) Air Conditioner Compressor
(7) Crankshaft Pulley
(8) Generator

1B Ð 26 AIR CONDITIONING
Removal
1. Disconnect the battery ground cable.
2. Discharge and recover refrigerant.
·Refer to Refrigerant Recovery in this section.
3. Disconnect magnetic clutch harness connector.
4. Remove radiator fan shroud.
5. Remove radiator fan.
·When the fan is removed, be sure to tighten
the fan fixing nuts temporarily to their original
positions.
6. Remove serpentine belt.
·Move serpentine belt tensioner to loose side
using wrench, then remove serpentine belt.
Legend
(1) Tensioner
(2) Idle Pulley
(3) Cooling Fan Pulley
(4) Serpentine Belt
(5) Power Steering Oil Pump
(6) Air Conditioner Compressor
(7) Crankshaft Pulley
(8) Generator
7. Disconnect refrigerant line connector.
·When removing the line connector, the
connecting part should immediately be
plugged or capped to prevent foreign matter
from being mixed into the line.
8. Remove compressor.
Installation
1. Install compressor.
·Tighten the compressor fixing bolts to the
specified torque.
Compressor Fixing Torque Nám (kgám / lbáft)
19 (1.9 / 14)
2. Connect refrigerant line connector.
·Tighten the refrigerant line connector fixing
bolts to the specified torque.
Refrigerant Line Bolt Torque Nám (kgám / lbáft)
15 (1.5 / 11)
·O-rings cannot be reused. Always replace with
new ones.
·Be sure to apply new compressor oil to the O-
rings when connecting refrigerant lines.
3. Install serpentine belt.
·Move serpentine belt tensioner to loose side
using wrench, then install serpentine belt to
normal position.
4. Install radiator fan.
5. Install radiator fan shroud.
6. Connect magnetic clutch harness connector.
3
4
2
7 86 1
5
850RX003

COMPRESSOR OVERHAUL 1D Ð 25
1. Perform oil return operation.
2. Discharge and recover the refrigerant and remove
the compressor.
3. Drain the compressor oil and measure the extracted
oil.
4. Check the compressor oil for contamination.
5. Adjust the oil level as required.
6. Evacuate, charge and perform the oil return
operation.
7. Check the system operation.
Contamination of Compressor Oil
Unlike engine oil, no cleaning agent is added to the
compressor oil. Even if the compressor runs for a long
period of time (approximately one season), the oil never
becomes contaminated as long as there is nothing
wrong with the compressor or its method of use.
Inspect the extracted oil for any of the following
conditions:
·The capacity of the oil has increased.
·The oil has changed to red.
·Foreign substances, metal powder, etc., are present
in the oil.
If any of these conditions exists, the compressor
oil is contaminated. Whenever contaminated
compressor oil is discovered, the receiver/drier
must be replaced.
Oil Return Operation
There is close affinity between the oil and the
refrigerant. During normal operation, part of the oil
recirculates with the refrigerant in the system. When
checking the amount of oil in the system, or replacing
any component of the system, the compressor must be
run in advance for oil return operation. The procedure
is as follows:
1. Open all the doors and the engine hood.
2. Start the engine and air conditioning switch to "ON"
and set the fan control knob at its highest position.
3. Run the compressor for more than 20 minutes
between 800 and 1,000 rpm in order to operate the
system.
4. Stop the engine.
Replacement of Component Parts
When replacing the system component parts, supply
the following amount of oil to the component parts to be
installed.
Compressor Leak Testing (External and
Internal)
Bench-Check Procedure
1. Install test plate J-39893 on rear head of compressor.
2. Using Refrigerant Recovery System, attach center
hose of manifold gage set on charging station to a
refrigerant drum standing in an upright drum.
3. Connect charging station high and low pressure
lines to corresponding fittings on test plate J-39893.
Suction port (low-side) of compressor has large
internal opening. Discharge port (high-side) has
smaller internal opening into compressor and
deeper recess.
4. Open low pressure control, high pressure control
and refrigerant control on charging station to allow
refrigerant vapor to flow into compressor.
5. Using a leak detector, check for leaks at pressure
relief valve, rear head switch location, compressor
front and rear head seals, center cylinder seal,
through bolt head gaskets and compressor shaft
seal. After checking, shut off low pressure control
and high-pressure control on charging station.
6. If an external leak is present, perform the necessary
corrective measures and recheck for leaks to make
certain the leak has been connected.
7. Recover the refrigerant.
8. Disconnect both hoses from the test plate J-39893.
9. Add 90 ml (3 oz.) new PAG lubricant to the
compressor assembly. Rotate the complete
compressor assembly (not the crankshaft or drive
plate hub) slowly several turns to distribute oil to all
cylinder and piston areas.
10. Install a M9 ´1.25 threaded nut on the compressor
crankshaft if the drive plate and clutch assembly are
not installed.
11. Using a box-end wrench or socket and handle,
rotate the compressor crankshaft or clutch drive
plate on the crankshaft several turns to insure
piston assembly to cylinder wall lubrication.
12. Using Refrigerant Recovery System, connect the
charging station high-pressure line to the test plate
J-39893 high-side connector.
13. Using Refrigerant Recovery System, connect the
charging station low-pressure line to the low
pressure port of the test plate J-39893. Oil will drain
out of the compressor suction port if the compressor
is positioned with the suction port downward. (Component parts to be (Amount of Oil)
installed)
Evaporator 50 cc (1.7 fl. oz.)
Condenser 30 cc (1.0 fl. oz.)
Receiver/dryer 30 cc (1.0 fl. oz.)
Refrigerant line (one 10 cc (0.3 fl. oz.)
piece)
(Amount of oil drained (Charging amount of oil
from used compressor) to new compressor)
more than 90 cc same as drained amount
(3.0 fl.oz)
less than 90 cc (3.0 fl.oz) 90 cc (3.0 fl.oz)

1D Ð 26 COMPRESSOR OVERHAUL
14. Attach the compressor to the J-34992 holding
fixture and mount the compressor in a vise so that
the compressor will be in a horizontal position and
the shaft can be turned with a wrench.
15. Using a wrench, rotate the compressor crankshaft
or drive plate hub ten complete revolutions at a
speed of approximately one-revolution per second
turning the compressor at less than one-revolution
per second can result in a lower pump-up pressure
and disqualify a good pumping compressor.
16. Observe the reading on high-pressure gauge at the
completion of the tenth revolution of the
compressor. The pressure reading for a good
pumping compressor should be 690 kPa (100 psi)
or above. A pressure reading of less than 620 kPa
(90 psi) would indicate one or more suction and/or
discharge valves leaking an internal leak, or an
inoperative valve, and the refrigerant must be
recovered and the compressor disassembled and
checked for cause of leak. Repair as needed,
reassemble and repeat the pump-up test. Externally
leak test.
17. When the pressure pump-up test is completed,
recover the refrigerant from the high-side and
remove the test plate J-39893.
18. Tilt the compressor so that the compressor suction
and discharge ports are down. Drain the PAG
lubricant from the compressor.
19. Allow the compressor to drain for 10 minutes, then
refill with the proper amount of PAG lubricant, per
oil balance procedure described previously. The
PAG lubricant may be poured into the suction port.
If further assembly or processing is required, a
shipping plate or test plate J-39893 should be
installed to keep out air, dirt and moisture until the
compressor is installed.

6A±1
ENGINE MECHANICAL
ENGINE
CONTENTS
Engine Mechanical 6A. . . . . . . . . . . . . . . . . . . . . .
Engine Cooling 6B. . . . . . . . . . . . . . . . . . . . . . . . .
Engine Fuel 6C. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Electrical 6D1. . . . . . . . . . . . . . . . . . . . . . . .
Ignition System 6D2. . . . . . . . . . . . . . . . . . . . . . . . .
Starting and Charging System 6D3. . . . . . . . . . . . Driveability and Emissions 6E. . . . . . . . . . . . . . . .
Engine Exhaust 6F. . . . . . . . . . . . . . . . . . . . . . . . .
Engine Lubrication 6G. . . . . . . . . . . . . . . . . . . . . .
Engine Speed Control System 6H. . . . . . . . . . . .
Inducton 6J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENGINE MECHANICAL
CONTENTS
Service Precaution 6A±2. . . . . . . . . . . . . . . . . . . . . .
General Description 6A±3. . . . . . . . . . . . . . . . . . . . .
Engine Diagnosis 6A±4. . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head Cover LH 6A±18. . . . . . . . . . . . . . . . .
Removal 6A±18. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±19. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head Cover RH 6A±21. . . . . . . . . . . . . . . . .
Removal 6A±21. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±22. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common Chamber 6A±24. . . . . . . . . . . . . . . . . . . . . .
Removal 6A±24. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±24. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Manifold LH 6A±26. . . . . . . . . . . . . . . . . . . . .
Removal 6A±26. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±26. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Manifold RH 6A±27. . . . . . . . . . . . . . . . . . . .
Removal 6A±27. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±27. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft Pulley 6A±28. . . . . . . . . . . . . . . . . . . . . . .
Removal 6A±28. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±28. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timing Belt 6A±29. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A±29. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±30. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft 6A±33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A±33. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±33. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head 6A±37. . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A±37. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±37. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Stem Oil Controller , Valve Spring and
Valve Guide 6A±39. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A±39. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±39. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Piston, Piston Ring and Connecting Rod 6A±40. . . Removal 6A±40. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±41. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft and Main Bearings 6A±42. . . . . . . . . . . .
Removal 6A±42. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±43. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Oil Seal 6A±47. . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A±47. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±47. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Assembly 6A±48. . . . . . . . . . . . . . . . . . . . . . . .
Removal 6A±48. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 6A±48. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head 6A±52. . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Associated Parts 6A±52. . . . .
Disassembly 6A±52. . . . . . . . . . . . . . . . . . . . . . . . . .
Clean 6A±53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A±53. . . . . . . . . . . . . . . . . .
Reassembly 6A±53. . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Spring, Oil Controller, Valve,
Valve Guide 6A±56. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Spring, Oil Controller, Valve,
Valve Guide and Associated Parts 6A±56. . . . . . .
Disassembly 6A±56. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A±57. . . . . . . . . . . . . . . . . .
Reassembly 6A±60. . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Clearance Adjustments 6A±61. . . . . . . . . . . . .
Camshaft 6A±63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft and Associated Parts 6A±63. . . . . . . . .
Disassembly 6A±63. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A±64. . . . . . . . . . . . . . . . . .
Reassembly 6A±66. . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft 6A±69. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft and Associated Parts 6A±69. . . . . . . .
Disassembly 6A±69. . . . . . . . . . . . . . . . . . . . . . . . . .
Inspection and Repair 6A±70. . . . . . . . . . . . . . . . . .
Inspection and Repair 6A±71. . . . . . . . . . . . . . . . . .
Reassembly 6A±73. . . . . . . . . . . . . . . . . . . . . . . . . .

6A±3
ENGINE MECHANICAL
General Description
Engine Cleanliness And Care
An automobile engine is a combination of many
machined, honed, polished and lapped surfaces with
tolerances that are measured in the thousandths of a
millimeter (ten thousandths of an inch). Accordingly,
when any internal engine parts are serviced, care and
cleanliness are important. Throughout this section, it
should be understood that proper cleaning and protection
of machined surfaces and friction areas is part of the
repair procedure. This is considered standard shop
practice even if not specifically stated.

A liberal coating of engine oil should be applied to all
friction areas during assembly to protect and lubricate
the surfaces on initial operation.

Whenever valve train components, pistons, piston
rings, connecting rods, rod bearings, and crankshaft
journal bearings are removed for service, they should
be retained in order.

At the time of installation, they should be installed in
the same locations and with the same mating
surfaces as when removed.

Battery cables should be disconnected before any
major work is performed on the engine. Failure to
disconnect cables may result in damage to wire
harness or other electrical parts.

The six cylinders of this engine are identified by
numbers; Right side cylinders 1, 3 and 5, Left side
cylinders 2, 4 and 6, as counted from crankshaft
pulley side to flywheel side.
General Information on Engine Service
The following information on engine service should be
noted carefully, as it is important in preventing damage
and contributing to reliable engine performance:

When raising or supporting the engine for any reason,
do not use a jack under the oil pan. Due to the small
clearance between the oil pan and the oil pump
strainer, jacking against the oil pan may cause
damage to the oil pick±up unit.

The 12±volt electrical system is capable of damaging
circuits. When performing any work where electrical
terminals could possibly be grounded, the ground
cable of the battery should be disconnected at the
battery.

Any time the intake air duct or air cleaner is removed,
the intake opening should be covered. This will
protect against accidental entrance of foreign
material into the cylinder which could cause extensive
damage when the engine is started.
Cylinder Block
The cylinder block is made of aluminum die±cast casting
for 75
V±type six cylinders. It has a rear plate integrated
structure and employs a deep skint. The cylinder liner is
cast and the liner inner diameter and crankshaft journal
diameter are classified into grades. The crankshaft is
supported by four bearings of which width of No.3 bearing
on the body side is different in order to support the thrust
bearing. The bearing cap is made of nodular cast iron and
each bearing cap uses four bolts and two side bolts.
Cylinder Head
The cylinder head, made of aluminum alloy casting
employs a pent±roof type combustion chamber with a
spark plug in the center. The intake and exhaust valves
are placed in V±type design. The ports are cross±flow
type.
Valve Train
Intake and exhaust camshaft on the both side of banks
are driven through an camshaft drive gear by timing belt.
The valves are operated by the camshaft and the valve
clearance is adjusted to select suitable thickness shim.
Intake Manifold
The intake manifold system is composed of the aluminum
cast common chamber and intake manifold attached with
six fuel injectors.
Exhaust Manifold
The exhaust manifold is made of nodular cast iron.
Pistons and Connecting Rods
Aluminum pistons are used after selecting the grade that
meets the cylinder bore diameter. Each piston has two
compression rings and one oil ring. The piston pin is made
of chromium steel is offset 1mm toward the thrust side,
and the thrust pressure of piston to the cylinder wall varies
gradually as the piston travels. The connecting rods are
made of forged steel. The connecting rod bearings are
graded for correct seze selection.
Crankshaft and Bearings
The crankshaft is made of Ductile cast±iron. Pins and
journals are graded for correct size selection for their
bearing.
Engine Lubrication
The oil discharged by a trochoid±type oil pump driven by
the crankshaft is fed through full±flow oil filter and to the oil
gallery provided under the crankshaft bearing cap. The oil
is then led to the crankshaft journals and cylinder head.
The crank pins are lubricated with oil from crankshaft
journals through oil holes. Also, an oil jet is fed to each
cylinder from crankshaft juornals on the connecting rod
for piston cleaning. The oil pan flange is dealed with liquid
packing only; do not deform or damage the flange surface
during removal or installation.

6A±11
ENGINE MECHANICAL
Condition CorrectionPossible cause
Engine overheatingLevel of Engine Coolant too lowReplenish
Fan clutch defectiveReplace
Incorrect fan installedReplace
Thermostat defectiveReplace
Engine Coolant pump defectiveCorrect or replace
Radiator cloggedClean or replace
Radiator filler cap defectiveReplace
Level of oil in engine crankcase too
low or wrong engine oilChange or replenish
Resistance in exhaust system
increasedClean exhaust system or replace
defective parts
Throttle Position Sensor adjustment
incorrectReplace with Throttle Valve ASM
Throttle Position Sensor circuit open
or shortedCorrect or replace
Cylinder head gasket damagedReplace
Engine overcoolingThermostat defectiveReplace (Use a thermostat set to
open at 82
C (180
F))
Engine lacks compressionÐÐÐÐRefer to Hard Start
OthersTire inflation pressure abnormalAdjust to recommended pressures
Brake dragAdjust
Clutch slippingAdjust or replace
Level of oil in engine crankcase too
highCorrect level of engine oil
Exhaust Gas Recirculation Valve
defectiveReplace
Engine Noisy
Abnormal engine noise often consists of various noises
originating in rotating parts, sliding parts and othermoving parts of the engine. It is, therefore, advisable to
locate the source of noise systematically.
Condition
Possible causeCorrection
Noise from crank journals or from
crank bearings
(Faulty crank journals and crankOil clearance increased due to worn
crank journals or crank bearingsReplace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
yj
bearings usually make dull noise that
becomes more evident when
accelerating)Crankshaft out of roundReplace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
Crank bearing seizedCrank bearing seized. Replace crank
bearings and crankshaft or regrind
crankshaft and install the undersize
bearing
Troubleshooting Procedure
Short out each spark plug in sequence using insulated
spark plug wire removers. Locate cylinder with defectivebearing by listening for abnormal noise that stops when
spark plug is shorted out.