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Volvo 850 troubleshoot guide

Volvo 850 service & repair manual

TROUBLE SHOOTING – BASIC PROCEDURES

1995 Volvo 850

GENERAL TROUBLE SHOOTING

* PLEASE READ THIS FIRST *

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.

ACCESSORIES & ELECTRICAL

CHARGING SYSTEM TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC CHARGING SYSTEM TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Vehicle Will Not Dead battery Check battery cells, Start alternator belt tension and alternator output
Loose or corroded battery Check all charging connections system connections
Ignition circuit or switch Check and replace as malfunction necessary

condition, See Belt

Alternator Light

Loose

or worn alternator

Check alternator drive

Stays On With

drive

belt

tension and

Engine Running

Adjustment in TUNE-UP

article in the

Loose

alternator wiring

TUNE-UP section

Check all charging

connections system connections
Short in alternator light See Indicator Warning wiring Lights in STANDARD
INSTRUMENTS in the ACCESSORIES & EQUIPMENT section
Defective alternator stator See Bench Tests in or diodes ALTERNATOR article
Defective regulator See Regulator Check in
ALTERNATOR article
Alternator Blown fuse See WIRING DIAGRAMS Light Stays Off
With Ignition
Switch ON
Defective alternator See Testing in
ALTERNATOR article
Defective indicator light See Indicator Warning bulb or socket Lights in STANDARD
INSTRUMENTS in the ACCESSORIES & EQUIPMENT section
Alternator Short in alternator wiring See On-Vehicle Tests Light Stays OFF in ALTERNATOR article With Ignition
Switch ON
Defective rectifier bridge See Bench Tests in
ALTERNATOR article
Lights or Fuses Defective alternator wiring See On-Vehicle Tests Burn Out in ALTERNATOR article Frequently
Defective regulator See Regulator Check in
ALTERNATOR article
Defective battery Check and replace as necessary

Ammeter Gauge

Shows Discharge

Loose or worn drive

belt

Check alternator drive belt tension and condition. See Belt Adjustment in TUNE-UP article in the

TUNE-UP section

Defective wiring

Check all wires and wire connections

Defective alternator or regulator

See Bench Tests and On-Vehicle Tests in ALTERNATOR article

Defective ammeter, or improper ammeter wiring connection

See Testing in STANDARD INSTRUMENTS in the ACCESSORIES & EQUIPMENT section

Noisy

Alternator

Loose drive pulley

Tighten drive pulley attaching nut

Loose mounting bolts

Tighten all alternator mounting bolts

Worn or dirty bearings

See Bearing

Replacement

ALTERNATOR article

Defective diodes or stator See Bench Test in
ALTERNATOR article

belt tension and

Battery Does

Loose

or

worn drive

belt

Check alternator drive

Stay Charged

condition. See

Belt Adjustment in

appropriate TUNE-UP

article in the

TUNE-UP section

Loose or corroded battery Check all charging connections system connections
Loose alternator connections Check all charging system connections
Defective alternator or See On-Vehicle Tests battery and Bench Tests in
ALTERNATOR article
Add-on electrical accessories Install larger exceeding alternator capacity alternator
Battery Defective battery Check alternator Overcharged- output and repair as Uses Too Much necessary
Water
Defective alternator See On-Vehicle Test and Bench Tests in ALTERNATOR article
Excessive alternator voltage Check alternator output and repair as necessary

IGNITION SYSTEM TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
Ignition Secondary Trouble Shooting Chart
START: Visually inspect Spark Plug Wires, Coil Wires, Plug Wire Boots, Rotor, and Distributor Cap for signs of damage.
OK NOT OK

damaged components

as necessary

* To test secondary ignition

*

Repair or replace

system, modify a Spark Plug

by attaching a ground wire

to the body of the plug and

widening the gap to 1/4-3/8″. Disconnect spark plug wire
and insert test plug. Ground plug, crank engine, and
check for spark.
GOOD SPARK NO SPARK
* If plug sparks, driveability * Remove coil wire from the problem is most likely NOT distributor and attach the in the ignition system. modified spark plug. Ground
the plug and crank engine while checking for spark.

PRIMARY TROUBLE SHOOTING

CHECK CHART below in this

article.

*

GOOD SPARK

If plug has a good spark,

*

NO SPARK

Proceed to the IGNITION

the problem is in the plug

wires, distributor cap, or

rotor. Replace components

as necessary.

Ignition Primary Trouble Shooting Chart
START: Visually inspect primary ignition wires for broken, frayed, split, or cut wires. Also check for loose, corroded, or disconnected connectors.
OK NOT OK

components as necessary.

*

Check

that battery voltage

*

Repair or replace damaged

is at

least 11.5 volts.

NOT OK OK
* Replace or recharge the * Check for battery voltage battery. at the positive terminal of
the coil.
OK NOT OK
* Check air Gap of the Pick-Up * Check resistance of ballast coil in the distributor. resistor (if used) for the
correct resistance value.
OK NOT OK

necessary.

*

Check Pick-Up coil

for

*

Adjust or replace as

correct resistance

value.

NOT OK OK
* Replace Pick-Up coil if * Check control module for not to specification. good ground connections.
OK
* If vehicle fails to run at this point, go to the appropriate article in the ENGINE PERFORMANCE section.
OK NOT OK

if the measured resistance

value is not within

specification.

*

Check wires from the battery/

*

Replace ballast resistor

ignition switch to the coil.

Also check the coil primary

and secondary resistance.

STARTER TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC STARTER TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Starter Fails Dead battery or bad Check battery charge to Operate connections between and all wires and
starter and battery connections to starter
Ignition switch faulty Adjust or replace or misadjusted ignition switch
Open circuit between Check and repair wires starter switch ignition and connections as terminal on starter relay necessary
Starter relay or starter See Testing in STARTER
defective article

Open solenoid pull-in wire

See Testing in STARTER

article

Starter Does Not Operate and Headlights Dim

Weak battery or dead cell

Loose or corroded battery connections

Charge or replace battery as necessary

Check that battery connections are clean and tight

Internal ground in starter windings

See Testing in STARTER

article

Grounded starter fields

See Testing in STARTERS

Armature rubbing on pole shoes

See STARTER article

Starter Turns

Starter clutch slipping

See STARTER article

but Engine

Does Not Rotate

Broken clutch housing

See STARTER article

Pinion shaft rusted or See STARTER article dry
Engine basic timing See Ignition Timing in incorrect TUNE-UP article
Broken teeth on engine Replace flywheel and flywheel check for starter pinion
gear damage
Starter Will Not Faulty overrunning See STARTER article
Crank Engine clutch
Broken clutch housing See STARTER article
Broken flywheel teeth Replace flywheel and check for starter pinion gear damage
Armature shaft sheared See STARTER article or reduction gear teeth
stripped
Weak battery Charge or replace battery as necessary

See On-Vehicle Tests inSTARTER article

Check all ground connections for tight and clean connections

Charge or replace

battery as necessary

Faulty solenoid

Poor grounds

Ignition switch or misadjusted

faulty

Adjust or replace ignition switch as necessary

Starter Cranks

Battery weak or

Engine Slowly

defective

Engine overheated See ENGINE COOLING SYSTEM article
Engine oil too heavy Check that proper viscosity oil
is used
Poor battery-to-starter Check that all connections between
battery and starter are clean and tight
Current draw too low or See Bench Tests in too high STARTER article
Bent armature, loose pole See STARTER article shoes screws or worn
bearings
Burned solenoid contacts Replace solenoid
Faulty starter Replace starter
Starter Engages Engine timing too far See Ignition Timing in Engine Only advanced TUNE-UP article Momentarily
Overrunning clutch not Replace overrunning engaging properly clutch. See STARTER
article
Broken starter clutch See STARTER article
Broken teeth on engine Replace flywheel and flywheel check starter pinion
gear for damage
Weak drive assembly See STARTER article thrust spring
Weak hold-in coil See Bench Tests in
STARTER article
Starter Drive Defective point assembly See Testing in STARTER Will Not Engage article
Poor point assembly ground See Testing in STARTER
article
Defective pull-in coil Replace starter solenoid

Charge or replace battery as necessary

Check all wiring and connections leading to relay

switch

Starter Relay

Does Not Close

Dead battery

Faulty wiring

Neutral safety

switch

Replace neutral safety

faulty

Starter relay faulty Replace starter relay

Starter Drive

Starter motor loose on

Tighten starter

Will Not

mountings

attach bolts

Disengage

Worn drive end bushing

See STARTER article

Damaged engine flywheel Replace flywheel and teeth starter pinion gear for
damage
Drive yolk return spring Replace return spring broken or missing
Faulty ignition switch Replace ignition switch
Insufficient clearance Replace starter between winding leads to solenoid solenoid terminal and main
contact in solenoid
Starter clutch not Replace starter clutch disengaging
Ignition starter switch Replace ignition switch contacts sticking
Starter Relay Faulty solenoid switch, Check all wiring Operates but switch connections or between relay and Solenoid Does Not solenoid or replace
relay or solenoid as necessary
Broken lead or loose Repair wire or wire soldered connections connections as
necessary
Solenoid Plunger Weak battery Charge or replace Vibrates When battery as necessary Switch is Engaged
Solenoid contacts Clean contacts or corroded replace solenoid
Faulty wiring Check all wiring leading to solenoid
Broken connections inside Repair connections or switch cover replace solenoid
Open hold-in wire Replace solenoid
Low Current Draw Worn brushes or weak Replace brushes or brush springs as necessary
High Pitched Whine Distance too great Align starter or check During Cranking between starter that correct starter Before Engine pinion and flywheel and flywheel are being Fires but Engine used
Fires and Cranks
Normally
High Pitched Distance too small between
Whine After Engine starter pinion and flywheel
Fires With Key Flywheel runout contributes released. Engine to the intermittent nature Fires and Cranks
Normally

AIR CONDITIONING & HEAT

AIR CONDITIONING TROUBLE SHOOTING

WARNING: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC AIR CONDITIONING TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE
Compressor Not Working Compressor clutch circuit open.
Compressor clutch coil inoperative. Poor clutch ground connection.
Fan belts loose.
Thermostatic switch inoperative. Thermostatic switch not adjusted. Ambient temperature switch open. Superheat fuse blown.
Excessive Noise or Vibration Missing or loose mounting bolts.
Bad idler pulley bearings.
Fan belts not tightened correctly. Compressor clutch contacting body. Excessive system pressure. Compressor oil level low.
Damaged clutch bearings. Damaged reed valves. Damaged compressor.
Insufficient or No Cooling;
Compressor Working Expansion valve inoperative.
Heater control valve stuck open. Low system pressure.
Blocked condenser fins. Blocked evaporator fins. Vacuum system leak.
Vacuum motors inoperative.
Control cables improperly adjusted. Restricted air inlet.
Mode doors binding.
Blower motor inoperative. Temperature above system capacity.

HEATER SYSTEM TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC HEATER SYSTEM TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE Insufficient, Erratic,
or No Heat Low Coolant Level
Incorrect thermostat.
Restricted coolant flow through heater core.
Heater hoses plugged. Misadjusted control cable. Sticking heater control valve. Vacuum hose leaking.
Vacuum hose blocked.
Vacuum motors inoperative. Blocked air inlet.
Inoperative heater blower motor. Oil residue on heater core fins. Dirt on heater core fins.
Too Much Heat Improperly adjusted cables.
Sticking heater control valve.
No vacuum to heater control valve. Temperature door stuck open.
Air Flow Changes During
Acceleration Vacuum system leak.
Bad check valve or reservoir.
Air From Defroster At All
Times Vacuum system leak.
Improperly adjusted control cables. Inoperative vacuum motor.
Blower Does Not Operate
Correctly Blown fuse.
Blower motor windings open. Resistors burned out.
Motor ground connection loose. Wiring harness connections loose. Blower motor switch inoperative. Blower relay inoperative.
Fan binding or foreign object in housing.
Fan blades broken or bent.

BRAKES

BRAKE SYSTEM TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BRAKE SYSTEM TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION Brakes Pull Left
or Right Incorrect tire pressure Inflate tires to proper
pressure
Front end out of alignment See WHEEL ALIGNMENT Mismatched tires Check tires sizes Restricted brake lines
or hoses Check hose routing
Loose or malfunctioning
caliper See DISC BRAKES or
BRAKE SYSTEM
Bent shoe or oily linings See DRUM BRAKES or
BRAKE SYSTEM
Malfunctioning rear brakes See DRUM, DISC BRAKES
or BRAKE SYSTEM
Noises Without
Loose suspension parts See SUSPENSION
Brakes Applied Front linings worn out Replace linings
Noises With
Dust or oil on drums See DRUM, DISC BRAKES
or rotors or BRAKE SYSTEM
Brakes Applied Insulator on outboard See DISC BRAKES or shoe damaged BRAKE SYSTEM
Incorrect pads or linings Replace pads or linings
Brake Rough, Chatters
or Pulsates Excessive lateral runout Check rotor runout
Parallelism not to
specifications Reface or replace rotor
Wheel bearings not adjusted See SUSPENSION
Rear drums out-of-round Reface or replace drums
Excessive Pedal
Disc pad reversed, steel
against rotor Remove and reinstall pad
Effort Malfunctioning power unit See POWER BRAKES or
BRAKE SYSTEM
Partial system failure Check fluid and pipes Worn disc pad or lining Replace pad or lining Caliper piston stuck or
sluggish See DISC BRAKES or
BRAKE SYSTEM
Master cylinder piston
stuck See MASTER CYLINDERS
or BRAKE SYSTEM
Brake fade due to incorrect
pads for linings Replace pads or linings
Linings or pads glazed Replace pads or linings
Excessive Pedal
Worn drums Reface or replace drums
Travel Partial brake system failure Check fluid and pipes
Insufficient fluid in
master cylinder See MASTER CYLINDERS or
BRAKE SYSTEM
Air trapped in system See BRAKE BLEEDING or
BRAKE SYSTEM
Rear brakes not adjusted See Adjustments in DRUM BRAKES or BRAKE SYSTEM
Bent shoe or lining See DRUM BRAKES or
BRAKE SYSTEM
Plugged master cylinder cap See MASTER CYLINDERS
or BRAKE SYSTEM
Pedal Travel
Improper brake fluid Replace brake fluid
Decreasing Compensating port plugged See MASTER CYLINDERS
or BRAKE SYSTEM
Swollen cup in master
cylinder See MASTER CYLINDERS
or BRAKE SYSTEM
Master cylinder piston
not returning See MASTER CYLINDERS
or BRAKE SYSTEM
Weak shoe retracting springs See DRUM BRAKES BRAKE SYSTEM
Dragging
Wheel cylinder piston
sticking See DRUM BRAKES or
BRAKE SYSTEM
Brakes Master cylinder pistons
not returning See MASTER CYLINDERS BRAKE SYSTEM
Restricted brake lines
or hoses Check line routing
Incorrect parking brake
adjustment See DRUM BRAKES BRAKE SYSTEM
Parking Brake cables frozen See DRUM BRAKES BRAKE SYSTEM
Incorrect installation of
inboard disc pad Remove and replace correctly
Power booster output
rod too long See POWER BRAKE UNITS BRAKE SYSTEM
Brakes Grab or
Uneven Braking
Brake pedal not returning See DISC, DRUM BRAKES
freely BRAKE SYSTEM
Action Malfunction of combination See CONTROL VALVE or valve BRAKE SYSTEM
Malfunction of power brake See POWER BRAKE UNITS
unit or BRAKE SYSTEM
Pulsation or
Binding brake pedal See DISC, DRUM BRAKES
or BRAKE SYSTEM
Roughness Uneven pad wear caused by See DISC BRAKES or caliper BRAKE SYSTEM
Uneven rotor wear See DISC BRAKES or
BRAKE SYSTEM
Drums out-of-round Reface or replace drums

ENGINE MECHANICAL

COOLING SYSTEM TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
COOLING SYSTEM TROUBLE SHOOTING
CONDITION POSSIBLE CAUSE CORRECTION Overheating Coolant Leak Fill/Pressure Test
System
A/C Condenser Fins Clogged Remove/Clean Condenser
Radiator Fins Clogged Remove/Clean Radiator Thermostat Stuck Closed Replace Thermostat Clogged Cooling System
Passages Clean/Flush Cooling
System
Water Pump Malfunction Replace Water Pump Fan Clutch Malfunction Replace Fan Clutch Retarded Ignition Timing Reset Ignition Timing
Cooling Fan Malfunction Test Cooling Fan/ Circuit
Cooling Fan Motor
Malfunction Test Fan Motor
Cooling Fan Relay
Malfunction Test Fan Relay
Faulty Radiator Cap Replace Radiator Cap Broken/Slipping Fan Belt Replace Fan Belt Restricted Exhaust Repair Exhaust System
Corrosion Impurities In Coolant Clean/Flush System
Coolant Leakage Damaged hose Replace Hose
Leaky Water Pump Replace Water Pump Damaged Radiator Seam Replace/Repair Radiator Leaky Thermostat Cover Replace Thermostat
Cover
Cylinder Head Problem Check Head/Head Gasket
Leaky Freeze Plugs Replace Freeze Plugs
Recovery System Inoperative
Loose and/or Defective
Radiator Cap Replace Radiator Cap
Overflow Tube Clogged
and/or Leaking Repair Tube
Recovery Bottle Vent
Restricted Clean Vent
No Heater Core Flow
Collapsed Heater Hose Replace Heater Hose
Plugged Heater Core Clean/Replace Heater
Core
Faulty Heater Valve Replace Heater Valve

GASOLINE ENGINE – MECHANICAL TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC GASOLINE ENGINE – MECHANICAL TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE CORRECTION

Incorrect ignition timing

Leaking valves

Worn fuel pump diaphragm or piston

Reset ignition timing, See TUNE-UP

Replace valves, See

ENGINES

Replace diaphragm or piston

Intake Backfire

Improper ignition timing

Faulty accelerator pump

Reset ignition timing, See TUNE-UP

Replace accelerator

discharge

Improper choke operation

Defective EGR valve

Fuel mixture too lean

Choke valve initial clearance too large

pump

Check choke and adjust as required

Replace EGR valve

Reset air/fuel mixture, See TUNE-UP

Reset choke valve initial clearance

Exhaust Backfire

Vacuum leak

Faulty vacuum diverter

Inspect and repair vacuum system

Replace vacuum diverter

valve

Faulty choke operation

Exhaust system leak

valve

Check choke and adjust as required

repair exhaust system leak

Engine

Detonation

Ignition timing too far advanced

Faulty ignition system

Spark plugs loose or faulty

Fuel delivery system clogged

EGR valve inoperative

PCV system inoperative

Vacuum leaks

Excessive combustion chamber deposits

Leaking, sticking or broken valves

Reset ignition timing, See TUNE-UP

Check ignition timing, See TUNE-UP

Retighten or replace plugs

Inspect lines, pump and filter for clog

Replace EGR valve Inspect and/or replace hoses or valve

Check vacuum system and repair leaks

Remove built-up deposits

Inspect and/or replace valves

External Oil

Fuel pump improperly seated

Remove pump, replace

Leakage

or worn gasket

gasket and seat

properly

Oil pan gasket broken or

Straighten pan and

pan bent

replace gasket

Timing chain cover gasket

Replace timing chain

broken

cover gasket

Rear main oil seal worn

Replace rear main oil

seal

Oil pan drain plug not

Remove and reinstall

seated properly

drain plug

Camshaft bearing drain

Remove restriction

hole blocked

Oil pressure sending

Remove and reinstall

switch leaking

sending switch

Excessive Oil Worn valve stems or guides Replace stems or
Consumption guides, See ENGINES Valve “O” ring seals Replace “O” ring seals, damaged See ENGINES
Plugged oil drain back holes Remove restrictions Improper PCV valve Replace PCV valve operation
Engine oil level too high Remove excess oil Engine oil too thin Replace thicker oil Valve stem oil deflectors Replace oil deflectors damaged
Incorrect piston rings Replace piston rings, See ENGINES
Piston ring gaps not Reinstall piston rings, staggered See ENGINES
Insufficient piston ring Replace rings, See tension ENGINES
Piston ring grooves or oil Replace piston rings, return slots clogged See ENGINES
Piston rings sticking in Replace piston rings, grooves See ENGINES
Piston ring grooves Replace piston and excessively worn rings, See ENGINES Compression rings installed Replace compression upside down rings correctly, See
ENGINES
Worn or scored cylinder Rebore cylinders or walls replace block Mismatched oil ring Replace oil ring expander and rail expander and rail, See
ENGINES
Intake gasket dowels too Replace intake gasket long dowels
Excessive main or connecting Replace main or rod bearing clearance connecting rod
bearings, See ENGINES
No Oil Pressure Low oil level Add oil to proper level Oil pressure sender or Replace sender or gauge gauge broken
Oil pump malfunction Remove and overhaul oil pump, See ENGINES
Oil pressure relief valve Remove and reinstall sticking valve
Oil pump passages blocked Overhaul oil pump, See
ENGINES
Oil pickup screen or tube remove restriction blocked
Loose oil inlet tube Tighten oil inlet tube
Loose camshaft bearings Replace camshaft bearings, See ENGINES
Internal leakage at oil Replace block or passages cylinder head
Low Oil Pressure Low engine oil level Add oil to proper level
Engine oil too thin Remove and replace with thicker oil
Excessive oil pump Reduce oil pump clearance clearance, See ENGINES Oil pickup tube or screen Remove restrictions blocked
Main, rod or cam bearing Replace bearing to clearance excessive reduce clearance, See
ENGINES
High Oil Improper grade of oil Replace with proper oil
Pressure Oil pressure relief valve Eliminate binding stuck closed
Oil pressure sender or Replace sender or gauge gauge faulty
Noisy Main Inadequate oil supply Check oil delivery to
Bearings main bearings
Excessive main bearing Replace main bearings, clearance See ENGINES
Excessive crankshaft end Replace crankshaft, See play ENGINES
Loose flywheel or torque Tighten attaching bolts converter
Loose or damaged vibration Tighten or replace damper vibration damper Crankshaft journals Re-grind crankshaft out-of-round journals
Excessive belt tension Loosen belt tension
Noisy Connecting Excessive bearing clearance Replace bearing, See
Rods or missing bearing ENGINES
Crankshaft rod journal Re-grind crankshaft out-of-round journal
Misaligned connecting rod Remove rod or cap and or cap realign
Incorrectly tightened rod Remove and re-tighten bolts rod bolts
Noisy Pistons Excessive piston-to-bore Install larger pistons, and Rings clearance See ENGINES
Bore tapered or out-of-round Rebore block
Piston ring broken Replace piston rings, See ENGINES
Piston pin loose or seized Replace piston pin, See
ENGINES
Connecting rods misaligned Realign connecting rods Ring side clearance too Replace with larger or loose or tight smaller rings
Carbon build-up on piston Remove carbon
Noisy Valve Worn or bent push rods Replace push rods, See
Train ENGINES
Worn rocker arms or bridged Replace push rods, See pivots ENGINES
Dirt or chips in valve Remove lifters and lifters remove dirt/chips Excessive valve lifter Replace valve lifters, leak-down See ENGINES
Valve lifter face worn Replace valve lifters, See ENGINES
Broken or cocked valve replace or reposition springs springs
Too much valve stem-to-guide Replace valve guides, clearance See ENGINES
Valve bent Replace valve, See
ENGINES
Loose rocker arms Retighten rocker arms, See ENGINES
Excessive valve seat Reface valve seats, See run-out ENGINES

Missing valve lock Excessively worn camshaft lobes

Plugged valve lifter oil holes

Faulty valve lifter check ball

Rocker arm nut installed upside down

Valve lifter incorrect for engine

Faulty push rod seat or lifter plunger

Install new valve lock Replace camshaft, See ENGINES

Eliminate restriction or replace lifter Replace lifter check ball, See ENGINES Remove and reinstall correctly

Remove and replace valve lifters

Replace plunger or push rod

Noisy Valves

Improper valve lash

Worn or dirty valve lifters

Worn valve guides

Excessive valve seat or

Re-adjust valve lash, See ENGINES

Clean and/or replace lifters

Replace valve guides, See ENGINES

Reface seats or valve

face run-out

Worn camshaft lobes

Loose rocker arm studs

Bent push rods

Broken valve springs

face

Replace camshaft, See

ENGINES

Re-tighten rocker arm studs, See ENGINES Replace push rods, See ENGINES

Replace valve springs, See ENGINES

Burned,Sticking or Broken Valves

Weak valve springs or warped valves

Improper lifter clearance

Worn guides or improper guide clearance

Out-of-round valve seats or improper seat width Gum deposits on valve stems, seats or guides Improper spark timing

Replace valves and/or springs, See ENGINES

Re-adjust clearance or replace lifters

Replace valve guides, See ENGINES

Re-grind valve seats

Remove deposits

Re-adjust spark timing

Broken

Pistons/Rings

Undersize pistons

Wrong piston rings

Out-of-round cylinder bore

Replace with larger pistons, See ENGINES Replace with correct rings, See ENGINES

Re-bore cylinder bore

Improper connecting rod alignment

Excessively worn ring grooves

Improperly assembled piston pins Insufficient ring gap clearance

Engine overheating

Incorrect ignition timing

Remove and realign connecting rods Replace pistons, See ENGINES

Re-assemble pin-to

-piston, See ENGINES Install new rings, See ENGINES

Check cooling system Re-adjust ignition timing, See TUNE-UP

Excessive

Leaks at manifold to

Replace manifold or

Exhaust Noise

head, or to pipe

pipe gasket

Exhaust manifold

Replace exhaust

cracked or broken manifold, See ENGINES

ENGINE PERFORMANCE

CARBURETOR TROUBLE SHOOTING:

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC COLD START SYMPTOMS TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

Check choke operation, see FUEL SYSTEMS

Check linkage, seeFUEL SYSTEM

Engine

Start

Won’t

Choke

not closing

Choke

linkage bent

Engine

Starts,

Choke

vacuum kick

setting

Check setting and

Then Dies too wide adjust see, FUEL SYSTEMS
Fast idle RPM too low Reset RPM to specif- ication, see TUNE-UP
Fast idle cam index Reset fast idle cam incorrect index, see FUEL
SYSTEMS
Vacuum leak Inspect vacuum system for leaks
Low fuel pump outlet Repair or replace pump, see FUEL SYSTEMS
Low carburetor fuel level Check float setting see FUEL SYSTEM

Engine Quits

Choke vacuum kick setting

Reset vacuum kick

Under Load

incorrect

setting,see FUEL

SYSTEMS

Fast idle cam index Reset fast idle cam incorrect index, see FUEL
SYSTEM
Incorrect hot fast idle Reset fast idle RPM, speed RPM see TUNE-UP

Engine Starts,

Choke vacuum kick set too

Reset vacuum kick,

Runs Up,Then

narrow

see FUEL SYSTEMS

Idles, Slowly

With Black Smoke

Fast idle cam index

Reset fast idle cam

incorrect index, see FUEL SYSTEMS
Hot fast idle RPM too low Reset fast idle RPM, see TUNE-UP
BASIC HOT START SYMPTOMS TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION Engine Won’t Engine flooded Allow fuel to
Start evaporate
BASIC COLD ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE CORRECTION

Defective choke control switchReplace choke control switch, see FUEL SYSTEMS

Plugged heat crossoverRemove restriction

system

Engine Stalls in

Gear

Choke vacuum kick incorrect

setting

Reset choke vacuum kick, see FUEL SYSTEMS

Fast idle

RPM incorrect

Reset fast idle RPM, see TUNE-UP

Fast idle incorrect

cam index

Reset fast idle cam see FUEL SYSTEMS

Acceleration or Stall

Sag

Defective switch

choke control

Replace choke control switch

Choke vacuum kick setting incorrect

Reset choke vacuum kick see, FUEL SYSTEMS

Float level incorrect

(too low)

Adjust float level, FUEL SYSTEMS

Accelerator pump defective

Repair or replace pump see FUEL SYSTEMS

Secondary throttles not closed

Inspect lockout adjustment,see FUEL SYSTEMS

Sag or Stall

After Warmup

Defective accelerator pump

Replace pump, see

FUEL SYSTEMS

Float level incorrect

(too low)

Adjust float level, see FUEL SYSTEMS

Backfiring &

Black Smoke

BASIC WARM ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Hesitation With Vacuum leak Inspect vacuum lines
Small Amount of
Gas Pedal Movement
Accelerator pump weak or Replace pump, see inoperable FUEL SYSTEMS
Float level setting too low Reset float level, see,FUEL SYSTEMS
Metering rods sticking or Inspect and/or binding replace rods, see
FUEL SYSTEMS
Carburetor idle or transfer Inspect system and system plugged remove restriction
Frozen or binding heated air Inspect heated air inlet door for binding
Hesitation With Defective accelerator pump Replace pump, see Heavy Gas Pedal FUEL SYSTEMS Movement
Metering rod carrier Remove restriction sticking or binding
Large vacuum leak Inspect vacuum system and repair leak
Float level setting too Reset float level, low see FUEL SYSTEMS
Defective fuel pump, lines Inspect pump, lines or filter and filter
Air door setting incorrect Adjust air door setting, see FUEL

DIESEL ENGINE TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
NOTE: Diesel engines mechanical diagnosis is the same as gasoline engines for items such as noisy valves, bearings, pistons, etc. The following trouble shooting covers only items pertaining to diesel engines.
BASIC DIESEL ENGINE TROUBLE SHOOTING CHART

CONDITION

POSSIBLE CAUSE

CORRECTION

Engine Won’t

Bad battery connections

Check connections

Crank

or dead batteries

and/or replace

batteries
Bad starter connections Check connections or bad starter and/or replace
batteries
Engine Cranks Bad battery connections Check connections Slowly, Won’t or dead batteries and/or replace Start batteries
Engine oil too heavy Replace engine oil
Engine Cranks Glow plugs not functioning Check glow plug system, Normally, But see FUEL SYSTEMS
Will Not Start Glow plug control not Check controller, see functioning FUEL SYSTEMS
Fuel not injected into Check fuel injectors, cylinders see FUEL SYSTEMS
No fuel to injection pump Check fuel delivery system
Fuel filter blocked Replace fuel filter
Fuel tank filter blocked Replace fuel tank filter
Fuel pump not operating Check pump operation and/or replace pump
Fuel return system blocked Inspect system and remove restriction
No voltage to fuel solenoid Check solenoid and connections
Incorrect or contaminated Replace fuel fuel
Incorrect injection pump Re-adjust pump timing, timing see FUEL SYSTEMS
Low compression Check valves, pistons, rings, see ENGINES
Injection pump malfunction Inspect and/or replace injection pump
Engine Starts, Incorrect slow idle Reset idle adjustment, Won’t Idle adjustment see TUNE-UP
Fast idle solenoid Check solenoid and malfunctioning connections
Fuel return system blocked Check system and remove restrictions
Glow plugs go off too soon See glow plug diagnosis in FUEL SYSTEMS
Injection pump timing Reset pump timing, see incorrect FUEL SYSTEMS
No fuel to injection pump Check fuel delivery system
Incorrect or contaminated Replace fuel fuel
Low compression Check valves, piston, rings, see ENGINES
Injection pump malfunction Replace injection pump, see FUEL SYSTEMS
Fuel solenoid closes in RUN Check solenoid and position connections
Engines Starts/ Incorrect slow idle Reset slow idle, see
Idles Rough W/out adjustment TUNE-UP
Smoke or Noise Injection line fuel leaks Check lines and connections
Fuel return system blocked Check lines and connections
Air in fuel system Bleed air from system
Incorrect or contaminated Replace fuel fuel
Injector nozzle malfunction Check nozzles, see
FUEL SYSTEMS
Engines Starts Injection pump timing Reset pump timing, see and Idles Rough incorrect FUEL SYSTEMS
W/out Smoke or Engine not fully broken in Put more miles on
Noise, But Clears engine
After Warm-Up Air in system Bleed air from system
Injector nozzle malfunction Check nozzles, see
FUEL SYSTEMS
Engine Idles Blocked fuel filter Replace fuel filter Correctly, Injection pump timing Reset pump timing, see Misfires Above incorrect FUEL SYSTEMS
Idle Incorrect or contaminated Replace fuel fuel
Engine Won’t Fast idle adjustment Reset fast idle, see
Return To Idle incorrect TUNE-UP
Internal injection pump Replace injection pump, malfunction see FUEL SYSTEMS External linkage binding Check linkage and
remove binding
Fuel Leaks On Loose or broken fuel line Check lines and
Ground connections
Internal injection pump Replace injection pump, seal leak see FUEL SYSTEMS
Cylinder Injector nozzles sticking Test injectors, see
Knocking Noise open FUEL SYSTEMS
Very low nozzle opening Test injectors and/or pressure replace
Loss of Engine Restricted air intake Remove restriction
Power EGR valve malfunction Replace EGR valve Blocked or damaged exhaust Remove restriction system and/or replace
components Blocked fuel tank filter Replace filter Restricted fuel filter Remove restriction
and/or replace filter
Block vent in gas cap Remove restriction and/or replace cap
Tank-to-injection pump fuel Check fuel lines and supply blocked connections
Blocked fuel return system Remove restriction
Incorrect or contaminated Replace fuel fuel
Blocked injector nozzles Check nozzle for blockage, see FUEL SYSTEMS
Low compression Check valves, rings, pistons, see ENGINES
Loud Engine Basic timing incorrect Reset timing, see
Noise With Black FUEL SYSTEMS
Smoke EGR valve malfunction Replace EGR valve Internal injection pump Replace injection pump, malfunction see FUEL SYSTEMS

Cooling system leaksBelt slipping or damagedThermostat stuck closedHead gasket leakingCheck cooling system and repair leaks Check tension and/or replace beltRemove and replace thermostat, see ENGINE COOLING Replace head gasket

Injector pump fuel solenoidRemove and check

does not return fuel valvesolenoid and replace

Incorrect injector pump housing pressure

Check pressure, see

FUEL SYSTEMS

Engine

Overheating

Oil Light on

Idle

at

Low oil pump pressure

Oil cooler or line

Check oil pump operation, see ENGINES Remove restriction

restricted

and/or replace cooler

Engine Won’t

Shut Off

to OFF position

if needed

VACUUM PUMP DIAGNOSIS
Excessive Noise Loose pump-to-drive Tighten screws assembly screws
Loose tube on pump assembly Tighten tube Valves not functioning Replace valves properly

Oil Leakage

Loose end plug

Tighten end plug

Bad seal crimp

Remove and re-crimp

seal

FUEL INJECTION TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC FUEL INJECTION TROUBLE SHOOTING CHART

circuit

CONDITION

POSSIBLE CAUSE

CORRECTION

Engine Won’t

Cold start valve inoperative

Test valve and

Start (Cranks

Normally)

Poor connection;vacuum or Check vacuum and wiring electrical
connections
Contaminated fuel Test fuel for water or alcohol
Defective fuel pump relay Test relay and or circuit wiring
Battery too low Charge and test battery

Low fuel pressure

Test pressure regul- ator and fuel pump, check for restricted lines and filters

No distributor reference pulses

Repair ignition system as necessary

Open coolant temperature sensor circuit

Test sensor and wiring

Shorted W.O.T. switch in

T.P.S.

Disconnect W.O.T. switch, engine should start

Defective ECM

Replace ECM

Fuel tank residual pressure valve leaks

Test for fuel pressure drop after shut down

Hard Starting

Disconnected hot air tube to air cleaner

Reconnect tube and test control valve

Defective Idle Air Control

(IAC) valve

Test valve operation and circuit

Shorted, open or misadjusted

T.P.S.

Test and adjust or replace T.P.S.

EGR valve open

Test EGR valve and control circuit

Poor Oxygen sensor signal

Test for shorted or circuit

Incorrect mixture from PCV

system

Test PCV for flow, check sealing of oil filter cap

Poor High Speed

Operation

Low fuel pump volume

Faulty pump or restricted fuel lines or filters

Poor MAP sensor signal

Test MAP sensor, vacuum hose and wiring

Poor Oxygen sensor signal

Test for shorted or open sensor or circuit

Open coolant temperature sensor circuit

Test sensor and wiring

Faulty ignition operation

Check wires for cracks or poor con- nections, test secondary voltage with oscilloscope

Contaminated fuel

Test fuel for water

or alcohol
Intermittent ECM ground Test ECM ground connection for resistance
Restricted air cleaner Replace air cleaner
Restricted exhaust system Test for exhaust manifold back pressure
Poor MAF sensor signal Check leakage between sensor and manifold

If tester for ALCL hook-up is available check that VSS reading matches speedometer

open sensor or

Poor

VSS signal

Ping or Knock on

Poor

Knock sensor

signal

Test for shorted or

Acceleration

circuit

Poor Baro sensor signal Test for shorted or open sensor or circuit
Improper ignition timing See VEHICLE EMISSION CONTROL LABEL (where applicable)
Check for engine Low coolant, loose overheating problems belts or electric
cooling fan inoperative
NOTE: For additional electronic fuel injection trouble shooting information, see the appropriate article in the ENGINE PERFORMANCE section (not all vehicles have Computer Engine Control articles). Information is provided there for diagnosing fuel system problems on vehicles with electronic fuel injection.

IGNITION SYSTEM TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
Ignition Secondary Trouble Shooting Chart
START: Visually inspect Spark Plug Wires, Coil Wires, Plug Wire Boots, Rotor, and Distributor Cap for signs of damage.
OK NOT OK

damaged components

as necessary

*

To test secondary ignition

*

Repair or replace

system, modify a Spark Plug

by attaching a ground wire

to the body of the plug and

widening the gap to 1/4-3/8″.

Disconnect spark plug wire

and insert test plug. Ground

plug, crank engine, and

check for spark.

GOOD SPARK NO SPARK
* If plug sparks, driveability * Remove coil wire from the problem is most likely NOT distributor and attach the in the ignition system. modified spark plug. Ground
the plug and crank engine while checking for spark.

PRIMARY TROUBLE SHOOTING

CHECK CHART below in this

article.

*

GOOD SPARK

If plug has a good spark,

*

NO SPARK

Proceed to the IGNITION

the problem is in the plug

wires, distributor cap, or

rotor. Replace components

as necessary.

Ignition Primary Trouble Shooting Chart
START: Visually inspect primary ignition wires for broken, frayed, split, or cut wires. Also check for loose, corroded, or disconnected connectors.
OK NOT OK

components as necessary.

*

Check

that battery voltage

*

Repair or replace damaged

is at

least 11.5 volts.

NOT OK OK
* Replace or recharge the * Check for battery voltage battery. at the positive terminal of
the coil.
OK NOT OK
* Check air Gap of the Pick-Up * Check resistance of ballast coil in the distributor. resistor (if used) for the
correct resistance value.
OK NOT OK

necessary.

*

Check Pick-Up coil

for

*

Adjust or replace as

correct resistance

value.

NOT OK OK

good ground connections.

*

Replace Pick-Up coil if

*

Check control module for

not to specification.

OK
* If vehicle fails to run at this point, go to the appropriate article in the ENGINE PERFORMANCE section.
OK NOT OK

if the measured resistance

value is not within

specification.

*

Check wires from the battery/

*

Replace ballast resistor

ignition switch to the coil.

Also check the coil primary

and secondary resistance.

STARTER TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC STARTER TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Starter Fails Dead battery or bad Check battery charge to Operate connections between and all wires and
starter and battery connections to starter

Ignition switch faulty or misadjusted

Adjust or replace ignition switch

Open circuit between starter switch ignition terminal on starter relay

Check and repair wires and connections as necessary

Starter relay or starter defective

See Testing in STARTER

article

Open solenoid pull-in wire

See Testing in STARTER

article

Starter Does Not Operate and Headlights Dim

Weak battery or dead cell

Loose or corroded battery connections

Charge or replace battery as necessary

Check that battery connections are clean and tight

Internal ground in starter windings

See Testing in STARTER

article

Grounded starter fields

See Testing in STARTERS

Armature rubbing on pole shoes

See STARTER article

Starter Turns

Starter clutch slipping

See STARTER article

but Engine

Does Not Rotate

Broken clutch housing

See STARTER article

Pinion shaft rusted or See STARTER article dry
Engine basic timing See Ignition Timing in incorrect TUNE-UP article
Broken teeth on engine Replace flywheel and flywheel check for starter pinion
gear damage

Starter Will Not

Crank Engine

Faulty overrunning clutch

See STARTER article

Broken clutch housing

See STARTER article

Broken flywheel teeth

Replace flywheel and check for starter pinion gear damage

Armature shaft sheared or reduction gear teeth stripped

See STARTER article

Weak battery

Charge or replace battery as necessary

Faulty solenoid

See On-Vehicle Tests in

STARTER article

Poor grounds

Check all ground

connections for tight and clean connections
Ignition switch faulty Adjust or replace or misadjusted ignition switch as
necessary
Starter Cranks Battery weak or Charge or replace
Engine Slowly defective battery as necessary
Engine overheated See ENGINE COOLING SYSTEM article
Engine oil too heavy Check that proper viscosity oil
is used
Poor battery-to-starter Check that all connections between
battery and starter are clean and tight
Current draw too low or See Bench Tests in too high STARTER article
Bent armature, loose pole See STARTER article shoes screws or worn
bearings
Burned solenoid contacts Replace solenoid
Faulty starter Replace starter
Starter Engages Engine timing too far See Ignition Timing in Engine Only advanced TUNE-UP article Momentarily
Overrunning clutch not Replace overrunning engaging properly clutch. See STARTER
article
Broken starter clutch See STARTER article
Broken teeth on engine Replace flywheel and flywheel check starter pinion
gear for damage
Weak drive assembly See STARTER article thrust spring
Weak hold-in coil See Bench Tests in
STARTER article
Starter Drive Defective point assembly See Testing in STARTER Will Not Engage article
Poor point assembly ground See Testing in STARTER
article
Defective pull-in coil Replace starter solenoid
Starter Relay Dead battery Charge or replace

Does Not Close

Faulty wiring

battery as necessary

Check all wiring and

connections leading to relay

Neutral safety switch faulty

Replace neutral safety switch

Starter relay faulty

Replace starter relay

Starter Drive Will Not Disengage

Starter motor loose on mountings

Worn drive end bushing

Tighten starter attach bolts

See STARTER article

Damaged engine flywheel teeth

Replace flywheel and starter pinion gear for damage

Drive yolk return spring broken or missing

Replace return spring

Faulty ignition switch

Replace ignition switch

Insufficient clearance between winding leads to solenoid terminal and main contact in solenoid

Replace starter solenoid

Starter clutch not disengaging

Replace starter clutch

Ignition starter switch contacts sticking

Replace ignition switch

Starter Relay Operates but Solenoid Does Not

Faulty solenoid switch, switch connections or

Check all wiring between relay and solenoid or replace relay or solenoid as necessary

Broken lead or loose

Repair wire or wire

soldered connections connections as necessary
Solenoid Plunger Weak battery Charge or replace Vibrates When battery as necessary Switch is Engaged
Solenoid contacts Clean contacts or corroded replace solenoid
Faulty wiring Check all wiring leading to solenoid
Broken connections inside Repair connections or switch cover replace solenoid
Open hold-in wire Replace solenoid
Low Current Draw Worn brushes or weak Replace brushes or brush springs as necessary
High Pitched Whine Distance too great Align starter or check During Cranking between starter that correct starter Before Engine pinion and flywheel and flywheel are being Fires but Engine used
Fires and Cranks
Normally
High Pitched Distance too small between Whine After Engine starter pinion and flywheel Fires With Key Flywheel runout contributes released. Engine to the intermittent nature Fires and Cranks
Normally

TUNE-UP TROUBLE SHOOTING – GAS ENGINE VEHICLES

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC SPARK PLUG TROUBLE SHOOTING CHARTS
CONDITION POSSIBLE CAUSE CORRECTION Normal Spark Light Tan or Gray deposits No Action
Plug Condition
Electrode not burned or No Action fouled

mixture, see ENGINE PERFORMANCE section

Replace choke

Cold Fouling or

Gap tolerance not

Overrich air/fuel

changed

mixture

No Action

Adjust air/fuel

Carbon Deposits

Faulty choke

assembly, see ENGINE

PERFORMANCE section

Clogged air filter Clean and/or replace air filter
Incorrect idle speed or Reset idle speed and/
dirty carburetor or clean carburetor
Faulty ignition wires Replace ignition wiring

pistons

Prolonged operation at idle

Shut engine during long

off idle

Sticking valves or worn valve guide seals

Check valve

train

Wet Fouling

Worn rings and pistons

Install new

rings and

or Oil Deposits

Deposits in combustion chamber becoming fused to electrodeClean combustion chamber of deposits

Engine overheatingWrong type of fuelCheck cooling systemReplace with correct

Excessive cylinder wear

Rebore or replace block

Excessive valve guide clearance

Worn or loose bearing

Gap Bridged

Blistered

Electrode

fuel

Loose spark plugs

Retighten spark plugs

Over-advanced ignition timing

Reset ignition timing see ENGINE PERFORMANCE

Pre-Ignition

or

Incorrect type of fuel

Replace with correct

Melted Electrodes fuel
Incorrect ignition timing Reset ignition timing see ENGINE PERFORMANCE

Burned valves

Engine Overheating

Wrong type of spark plug,

Replace valves

Check cooling system

Replace with correct

too hot

spark plug, see

ENGINE PERFORMANCE

Chipped

Insulators

Severe detonation

Check for over- advanced timing or combustion

Improper gapping procedure

Re-gap spark plugs

Rust Colored

Deposits

Additives in unleaded fuel

Try different fuel brand

Water In Combus-

Blown head gasket or

Repair or replace

tion Chamber

cracked head

head or head gasket

NOTE: Before diagnosing an electronic ignition system, ensure that all wiring is connected properly between distributor, wiring connector and spark plugs. Ignition problem will show up either as: Engine Will Not Start or Engine Runs Rough.
BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS
CONDITION POSSIBLE CAUSE CORRECTION Engine Won’t Open circuit between Repair circuit

ignition switch

Open circuit between

Repair circuit

ignition switch and starter solenoid

Engine Runs

Rough

Fuel lines leaking or clogged

Tighten fitting, remove restriction

Initial timing incorrect

Reset ignition timing see ENGINE PERFORMANCE

Centrifugal advance malfunction

Repair distributor advance

Defective spark plugs or wiring

Replace plugs or plug wiring

Component Failure

Spark arc-over on cap, rotor or coil

Replace cap, rotor or or coil

Defective pick-up coil

Replace pick-up coil

Defective ignition coil

Replace ignition coil

Defective vacuum unit

Replace vacuum unit

Defective control module

Replace control module

BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS – USING OSCILLOSCOPE PATTERNS
CONDITION POSSIBLE CAUSE CORRECTION Firing Voltage Retarded ignition timing Reset ignition
Lines are the Same, timing, see ENGINE
but Abnormally High PERFORMANCE section
Fuel mixture too lean Readjust carburetor, see ENGINE PERFORMANCE
High resistance in coil Replace coil wire wire
Corrosion in coil tower Clean and/or replace terminal coil
Corrosion in distributor Clean and/or replace coil terminal distributor cap
Firing Voltage Fuel mixture too rich Readjust carburetor, Lines are the Same see ENGINE PERFORMANCE but Abnormally Low
Breaks in coil wire causing Replace coil wire arcing
Cracked coil tower causing Replace coil arcing
Low coil output Replace coil
Low engine compression Determine cause and
repair
One or More, But Carburetor idle mixture Readjust carburetor, Not All Firing not balanced see ENGINE PERFORMANCE Voltage Lines are
Higher Than Others EGR valve stuck open Clean and/or replace valve
High resistance in spark Replace spark plug plug wires wires

Cracked or broken spark plug insulator

Replace spark plugs

Intake vacuum leak

Repair leak

Defective spark plugs

Replace spark plugs

Corroded spark plug terminals

Replace spark plugs

One or More, But Not All Firing Voltage Lines Are Lower Than Others

Curb idle mixture not balanced

Breaks in plug wires causing arcing

Readjust carburetor, see ENGINE PERFORMANCE

Replace plug wires

Cracked coil tower causing arcing

Replace coil

Low compression

Determine cause and repair

Defective spark plugs

Replace spark plugs

Corroded spark plugs

Replace spark plugs

Cylinders Not

Firing

Cracked distributor cap terminals

Replace distributor cap

Shorted spark plug wire

Determine cause and repair

Mechanical problem in engine

Determine cause and repair

Defective spark plugs

Replace spark plugs

Spark plugs fouled

Replace spark plugs

BASIC DRIVEABILITY PROBLEMS TROUBLE SHOOTING TABLE CONDITION POSSIBLE CAUSE CORRECTION
Hard Starting Binding carburetor linkage Eliminate binding Binding choke linkage Eliminate binding Binding choke piston Eliminate binding
Restricted choke vacuum Check vacuum lines for blockage

see ENGINE PERFORMANCE

Worn or dirty needle valve and seat

Clean carburetor, see

ENGINE PERFORMANCE

Float sticking

Readjust or replace float see the ENGINE PERFORMANCE section

Incorrect choke adjustment

Reset choke adjustment see ENGINE PERFORMANCE

Defective coil

Replace coil

Improper spark plug gap

Regap spark plugs

Incorrect ignition timing

Reset ignition timing see ENGINE PERFORMANCE

Detonation

Over-advanced ignition timing

Reset ignition timing see ENGINE PERFORMANCE

Defective spark plugs

Replace spark plugs

Fuel lines clogged

Clean fuel lines

EGR system malfunction

Check and repair EGR

system

PCV system malfunction

Repair PCV system

Vacuum leaks

Check and repair vacuum system

Loose fan belts

Tighten or replace

fan belts, see ENGINE PERFORMANCE

Restricted airflow

Remove restriction

Vacuum advance malfunction

Check distributor operation

Dieseling

Binding carburetor linkage

Eliminate binding

Binding throttle linkage

Eliminate blinding

Binding choke linkage or fast idle cam

Eliminate binding

Defective idle solenoid

Replace idle solenoid see ENGINE PERFORMANCE

Improper base idle speed

Reset idle speed, see see ENGINE PERFORMANCE

Incorrect ignition timing

Reset ignition timing see ENGINE PERFORMANCE

Incorrect idle mixture setting

Reset idle mixture,

see ENGINE PERFORMANCE

Faulty

Incorrect ignition timing

Reset ignition timing

Acceleration

Engine cold and choke too Adjust choke and
lean allow engine to warm- up
Defective spark plugs Replace spark plugs
Defective coil Replace coil

slots, see FUEL

Faulty Low Speed

Clogged idle transfer

slots

Clean idle transfer

Operation

Restricted idle air bleeds Disassemble and clean and passages carburetor, see FUEL
Clogged air cleaner Replace air filter Defective spark plugs Replace spark plugs Defective ignition wires Replace ignition wire
see ENGINE PERFORMANCE
Defective distributor cap Replace distributor cap
Faulty High Speed Incorrect ignition timing Reset ignition timing
Operation see ENGINE PERFORMANCE
Defective distributor Replace advance

centrifugal advance

Defective distributor

mechanism

Replace advance unit

vacuum advance

Incorrect spark plugs or plug gap

Check gap and/or replace spark plugs

Faulty choke operation

Check choke and repair as required

Clogged vacuum passages

Remove restrictions

Improper size or clogged main jet

Check jet size and clean, see FUEL

Restricted air cleaner

Check filter and replace as necessary

Defective distributor cap, rotor or coil

Replace cap, rotor or coil

Misfire at

Speeds

All

Defective spark plugs

Replace spark plugs

Defective spark plug wires

Replace spark plug wires

Defective distributor cap, rotor, or coil

Replace cap, rotor, or coil

Cracked or broken vacuum

Replace vacuum hoses

hoses

Vacuum leaks Repair vacuum leaks
Fuel lines clogged Remove restriction
Hesitation Cracked or broken vacuum Replace vacuum hoses hoses
Vacuum leaks Repair Vacuum leaks Binding carburetor linkage Eliminate binding Binding throttle linkage Eliminate binding Binding choke linkage or Eliminate binding
fast idle cam
Improper float setting Readjust float setting, see FUEL
Cracked or broken ignition Replace ignition wires wires
Rough idle, Incorrect curb idle or fast Reset idle speed, see Missing or idle speed see ENGINE PERFORMANCE Stalling
Incorrect basic timing Reset ignition timing see ENGINE PERFORMANCE
Improper idle mixture Reset idle mixture, adjustment see ENGINE PERFORMANCE
Improper feedback system Check feedback system operation see ENGINE PERFORMANCE
Incorrect spark plug gap Reset spark plug gap, see ENGINE PERFORMANCE
Moisture in ignition Dry components components
Loose or broken ignition Replace ignition wires wires
Damaged distributor cap or Replace distributor or rotor cap or rotor
Faulty ignition coil Replace ignition coil Fuel filter clogged or worn Replace fuel filter Damaged idle mixture screw Replace idle mixture
screw, see FUEL
Improper fast idle cam Reset fast idle cam adjustment adjustment, see TUNE-
see ENGINE PERFORMANCE
Improper EGR valve operation Replace EGR valve Faulty PCV valve air flow Replace PCV valve Choke binding or improper Reset choke or
choke setting eliminate binding

Engine Surges

Vacuum leak

Improper float bowl fuel

Repair vacuum leak

Reset float

Engine Surges

level

adjustment, see FUEL

Engine Surges

Clogged air bleed or idle passages

Clean carburetor passages, see FUEL

Engine Surges

Clogged or worn air cleaner filter

Replace air filter

Engine Surges

Faulty choke vacuum diaphragm

Replace diaphragm,

see ENGINE PERFORMANCE

Engine Surges

Exhaust manifold heat valve inoperative

Replace heat valve

Engine Surges

Improper distributor spark advance

Check distributor operation

Engine Surges

Leaking valves or valve components

Check and repair valvetrain

Engine Surges

Improper carburetor mounting

Remove and remount carburetor

Engine Surges

Excessive play in distributor shaft

Replace distributor

Engine Surges

Loose or corroded wiring connections

Repair or replace as required

Engine Surges

Improper PCV valve airflow

Replace PCV valve

Engine Surges

Vacuum leaks

Repair vacuum leaks

Engine Surges

Clogged air bleeds

Remove restriction

Engine Surges

EGR valve malfunction

Replace EGR valve

Engine Surges

Restricted air cleaner filter

Replace air filter

Engine Surges

Cracked or broken vacuum hoses

Replace vacuum hoses

Engine Surges

Cracked or broken ignition wires

Replace ignition wires

Engine Surges

Vacuum advance malfunction

Check unit and replace as necessary

Engine Surges

Defective or fouled spark plugs

Replace spark plugs

Ping or Spark

Knock

Incorrect ignition timing

Reset ignition timing see ENGINE PERFORMANCE

Distributor centrifugal or vacuum advance malfunction

Check operation and replace as necessary

Carburetor setting too lean

Readjust mixture

setting, see ENGINE PERFORMANCE

Vacuum leak

Eliminate vacuum leak

EGR valve malfunction

Replace EGR valve

Poor Gasoline

Mileage

Cracked or broken vacuum hoses

Replace vacuum hoses

Vacuum leaks

Repair vacuum leaks

Defective ignition wires

Replace wires

Incorrect choke setting

Readjust setting, see

ENGINE PERFORMANCE

Defective vacuum advance

Replace vacuum advance

Defective spark plugs

Replace spark plugs

Binding carburetor power piston

Eliminate binding

Dirt in carburetor jets

Clean and/or replace jets

Incorrect float adjustment

Readjust float setting, see FUEL

Defective power valve

Replace power valve, see ENGINE PERFORMANCE

Incorrect idle speed

Readjust idle speed

Engine Stalls

Improper float level

Readjust float level

Leaking needle valve and seat

Replace needle valve and seat

Vacuum leaks

Eliminate vacuum

leaks

VACUUM PUMP – DIESEL TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
NOTE: Diesel engines mechanical diagnosis is the same as gasoline engines for items such as noisy valves, bearings, pistons, etc. The following trouble shooting covers only items pertaining to diesel engines.
VACUUM PUMP (DIESEL) TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

Excessive Noise

Loose pump-to-drive

Tighten

screws

assembly screws

Loose tube on pump assembly

Tighten

tube

Valves not functioning

Replace

valves

Oil Leakage

properly

Loose end plug

Tighten

end plug

Bad seal crimp Remove and re-crimp seal

MANUAL TRANSMISSION

MANUAL TRANSMISSION TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
MANUAL TRANSMISSION/TRANSAXLE TROUBLE SHOOTING Condition Possible Cause
Noisy In Forward Gears .Low gear oil level,
.Loose bell housing bolts,
.Worn bearings or gears
Clunk On Deceleration
(FWD Only) .Loose engine mounts,
.Worn inboard CV joints,
.Worn differential pinion shaft,
.Side gear hub counterbore in case worn oversize
Gear Clash When Shifting
Forward Gears .Clutch Out Of Adjustment,
.Shift linkage damaged or out of adjustment,
.Gears or synchronizers damaged,
.Low gear oil level
Transmission Noisy When
Moving (RWD Only) Quiet In
Neutral With Clutch Engaged .Worn rear outputshaft bearing
Gear Rattle .Worn bearings,
.Wrong gear oil,
.Low gear oil,
.Worn gears
Steady Ticking At Idle
(Increases With RPM) .Broken tooth on gear
Gear Clash When Shifting
Forward Gears .Worn or broken synchronizers
Loud Whine In Reverse .Normal condition (1)
Noise When Stepping On Clutch .Bad release bearing,
.Worn pilot bearing
Ticking Or Screeching As
Clutch Is Engaged .Faulty release bearing,
.Uneven pressure plate fingers
Click Or Snap When Clutch
Is Engaged .Worn clutch fork,
.Worn or broken front bearing retainer
Transmission Shifts Hard .Clutch not releasing,
.Shift mechanism binding,
.Clutch installed backwards
Will Not Shift Into One
Gear, Shifts Into All
Others .Bent shift fork,
.Worn detent balls
Locked Into Gear,
Cannot Shift .Clutch adjustment,
.Worn detent balls
Transmission Jumps Out
Of Gear .Pilot bearing worn,
.Bent shift fork,
.Worn gear teeth or face
.Excessive gear train end play
.Worn synchronizers
.Missing detent ball spring
.Shift mechanism worn or out of adjustment
.Engine or transmission mount bolts loose or out of adjustment
.Transmission not aligned
Shift Lever Rattle .Worn shift lever or detents
.Worn shift forks
.Worn synchronizers sleeve
Shift Lever Hops Under
Acceleration .Worn engine or transmission mounts
(1) – Most units use spur cut gears in reverse and are noisy

POWERTRAIN

CLUTCH TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC CLUTCH TROUBLE SHOOTING CHART

Oil, grease or glaze onDisassemble and clean

Oil or grease on clutchClean or replace clutch

facingsclutch disc

CONDITION

Chattering

or

POSSIBLE CAUSE

Incorrect clutch adjustment

CORRECTION

Adjust clutch

Grabbing

facings

or replace

Loose “U” joint flange

See DRIVE AXLES

article

Worn input shaft spline

Replace input shaft

Binding pressure plate

Replace pressure plate

Binding release lever

See CLUTCH article

Binding clutch disc hub

Replace clutch disc

Unequal pressure plate contact

Replace worn/misaligned components

Loose/bent clutch disc

Replace clutch disc

Incorrect transmission alignment

Realign transmission

Worn pressure plate, disc or flywheel

Replace damaged components

Broken or weak pressure springs

Replace pressure plate

Sticking clutch pedal

Lubricate clutch pedal

& linkage

Incorrect clutch disc facing

Replace clutch disc

Engine loose in chassis

Tighten all mounting bolts

Failure to

Release

Incorrect release lever or See CLUTCH article pedal adjustment
Worn or broken clutch Replace clutch disc facings
Bent clutch disc or Replace damaged pressure plate components
Clutch disc hub binding on Clean or replace clutch input shaft disc and/or input shaft
Binding pilot bearing Replace pilot bearing
Sticking release bearing Replace release bearing sleeve and/or sleeve
Binding clutch cable See CLUTCH article
Defective clutch master Replace master cylinder Defective clutch slave Replace slave cylinder Air in hydraulic system Bleed hydraulic system
Dry or binding clutch Lubricate and align pedal hub components
Floor mat interference Lay mat flat in proper with pedal area

switch

Dry or pivots

binding ball/fork

Lubricate and align components

Faulty

clutch cable

Replace clutch cable

Noisy Clutch

Faulty

interlock switch

Replace interlock

Pedal

Self-adjuster ratchet Lubricate or replace noise self-adjuster
Speed control interlock Lubricate or replace switch interlock switch
Clutch Pedal Binding clutch cable See CLUTCH article
Sticks Down
Springs weak in pressure Replace pressure plate plate
Binding in clutch linkage Lubricate and free linkage

Noisy

Dry release bearing

Lubricate or replace release bearing

Noisy

Dry or worn pilot bearing

Lubricate or replace bearing

Noisy

Worn input shaft bearing

Replace bearing

Transmission

Click

Weak springs in pressure plate

Replace pressure plate

Release fork loose on ball stud

Replace release fork and/or ball stud

Oil on clutch disc damper

Replace clutch disc

Broken spring in slave

Replace slave cylinder

cylinder

DRIVE AXLE – NOISE DIAGNOSIS

Unrelated Noises
Some driveline trouble symptoms are also common to the engine, transmission, wheel bearings, tires, and other parts of the vehicle. Ensure cause of trouble actually is in the drive axle before adjusting, repairing, or replacing any of its parts.
Non-Drive Axle Noises
A few conditions can sound just like drive axle noise and have to be considered in pre-diagnosis. The 4 most common noises are exhaust, tires, CV/universal joints and wheel trim rings.
In certain conditions, the pitch of the exhaust gases may sound like gear whine. At other times, it may be mistaken for a wheel bearing rumble.
Tires, especially radial and snow, can have a high-pitched tread whine or roar, similar to gear noise. Also, some non-standard tires with an unusual tread construction may emit a roar or whine.
Defective CV/universal joints may cause clicking noises or excessive driveline play that can be improperly diagnosed as drive axle problems.
Trim and moldings also can cause a whistling or whining noise. Ensure none of these components are causing the noise before disassembling the drive axle.
Gear Noise
A “howling” or “whining” noise from the ring and pinion gear can be caused by an improper gear pattern, gear damage, or improper bearing preload. It can occur at various speeds and driving conditions, or it can be continuous.
Before disassembling axle to diagnose and correct gear noise, make sure that tires, exhaust, and vehicle trim have been checked as possible causes.
Chuckle
This is a particular rattling noise that sounds like a stick against the spokes of a spinning bicycle wheel. It occurs while decelerating from 40 MPH and usually can be heard until vehicle comes to a complete stop. The frequency varies with the speed of the vehicle.
A chuckle that occurs on the driving phase is usually caused by excessive clearance due to differential gear wear, or by a damaged tooth on the coast side of the pinion or ring gear. Even a very small tooth nick or a ridge on the edge of a gear tooth is enough the cause the noise.
This condition can be corrected simply by cleaning the gear tooth nick or ridge with a small grinding wheel. If either gear is damaged or scored badly, the gear set must be replaced. If metal has broken loose, the carrier and housing must be cleaned to remove particles that could cause damage.
Knock
This is very similar to a chuckle, though it may be louder, and occur on acceleration or deceleration. Knock can be caused by a gear tooth that is damaged on the drive side of the ring and pinion gears. Ring gear bolts that are hitting the carrier casting can cause knock. Knock can also be due to excessive end play in the axle shafts.
Clunk
Clunk is a metallic noise heard when an automatic transmission is engaged in Reverse or Drive, or when throttle is applied or released. It is caused by backlash somewhere in the driveline, but not necessarily in the axle. To determine whether driveline clunk is caused by the axle, check the total axle backlash as follows:
1) Raise vehicle on a frame or twinpost hoist so that drive wheels are free. Clamp a bar between axle companion flange and a part of the frame or body so that flange cannot move.
2) On conventional drive axles, lock the left wheel to keep it from turning. On all models, turn the right wheel slowly until it is felt to be in Drive condition. Hold a chalk marker on side of tire about 12″ from center of wheel. Turn wheel in the opposite direction until it is again felt to be in Drive condition.
3) Measure the length of the chalk mark, which is the total
axle backlash. If backlash is one inch or less, drive axle is not the source of clunk noise.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by malfunctioning pinion bearings. Pinion
bearings operate at drive shaft speed. Roller wheel bearings may whine in a similar manner if they run completely dry of lubricant. Bearing noise will occur at all driving speeds. This distinguishes it from
gear whine, which usually comes and goes as speed changes.
Bearing Rumble
Bearing rumble sounds like marbles being tumbled. It is usually caused by a malfunctioning wheel bearing. The lower pitch is because the wheel bearing turns at only about 1/3 of drive shaft speed.
Chatter On Turns
This is a condition where the entire front or rear of vehicle vibrates when vehicle is moving. The vibration is plainly felt as well as heard. Extra differential thrust washers installed during axle repair can cause a condition of partial lock-up that creates this chatter.
Axle Shaft Noise
Axle shaft noise is similar to gear noise and pinion bearing whine. Axle shaft bearing noise will normally distinguish itself from gear noise by occurring in all driving modes (Drive, cruise, coast and float), and will persist with transmission in Neutral while vehicle is moving at problem speed.
If vehicle displays this noise condition, remove suspect axle shafts, replace wheel seals and install a new set of bearings.
Re-evaluate vehicle for noise before removing any internal components.
Vibration
Vibration is a high-frequency trembling, shaking or grinding condition (felt or heard) that may be constant or variable in level and can occur during the total operating speed range of the vehicle.
The types of vibrations that can be felt in the vehicle can be divided into 3 main groups:
* Vibrations of various unbalanced rotating parts of the vehicle.
* Resonance vibrations of the body and frame structures caused by rotating of unbalanced parts.
* Tip-in moans of resonance vibrations from stressed engine or exhaust system mounts or driveline flexing modes.

DRIVE AXLE – RWD TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing. For definitions
of listed noises or sounds, see DRIVE AXLE – NOISE DIAGNOSIS
under POWERTRAIN.
DRIVE AXLE (RWD) TROUBLE SHOOTING
CONDITION POSSIBLE CAUSE CORRECTION
Knocking or Clunking
Differential Side Gear
Clearance Check Clearance
Worn Pinion Shaft Replace Pinion Shaft Axle Shaft End Play Check End Play Missing Gear Teeth Check Differential/
Replace Gear
Wrong Axle Backlash Check Backlash
Misaligned Driveline Realign Driveline
Clinking During Engagement
Side Gear Clearance Check Clearance
Ring and Pinion Backlash Check Backlash Worn/Loose Pinion Shaft Replace Shaft/Bearing Bad “U” Joint Replace “U” Joint Sticking Slip Yoke Lube Slip Yoke
Broken Rear Axle Mount Replace Mount
Loose Drive Shaft Flange Check Flange
Click/Chatter On Turns
Differential Side Gear
Clearance Check Clearance

Change Lubricant

Wrong Turn On Plates

(1)

Replace Clutch Plates

Wrong Differential

Lubricant (1)

Knock Or Click

Flat Spot on Rear

Wheel Bearing Replace Wheel Bearing
Low Vibration At All Speeds
Faulty Wheel Bearing Replace Wheel Bearing
Faulty “U” Joint Replace “U” Joint Faulty Drive Shaft Balance Drive Shaft Faulty Companion Flange Replace Flange Faulty Slip Yoke Flange Replace Flange
(1) – Limited slip differential only.

FWD AXLE SHAFTS & CV JOINTS TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC FWD AXLE SHAFTS & CV JOINTS TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE
Grease Leaks CV boot torn or cracked
Clicking Noise on Cornering Damaged outer CV Clunk Noise on Acceleration Damaged inner CV
Vibration or Shudder Sticking, damaged or worn CV
on Acceleration Misalignment or spring height

STEERING & SUSPENSION

MANUAL STEERING GEAR TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC MANUAL STEERING GEAR TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

Rattle or Chucking Noise in Rack and Pinion

Rack and pinion mounting bracket loose

Lack of/or incorrect lubricant

Tighten all mounting bolts

Correct as necessary

Rattle or Chucking Noise in Rack and Pinion

Steering gear mounting bolts loose

Tighten all mounting bolts

Excessive Play

Front wheel bearing improperly adjusted

See FRONT SUSPENSION

article

Loose or worn steering linkage

See STEERING LINKAGE

article

Loose or worn steering gear shift

See MANUAL STEERING GEAR article

Steering arm loose on gear shaft

See MANUAL STEERING GEAR article

Steering gear housing bolts loose

Tighten all mounting bolts

Steering gear adjustment too loose

See MANUAL STEERING GEAR article

Steering arms loose on

Tighten and check

knuckles

Rack and pinion mounting

steering linkage

Tighten all mounting

loose

bolts

Rack and pinion out of adjustment

See adjustment in

STEERING article

Tie rod end loose

Tighten and check steering linkage

Excessive Pitman shaft-to- ball nut lash

Repair as necessary

Poor

Returnability

Lack of lubricant in ball joint or linkage

Lubricate and service systems

Binding in linkage or ball joints

See STEERING LINKAGE

and SUSPENSION article

Improper front end alignment

See WHEEL ALIGNMENT

article

Improper tire pressure

Inflate to proper pressure

Tie rod binding

Inflate to proper pressure

Shaft seal rubbing shaft

See STEERING COLUMN

article

Excessive

Vertical Motion

Improper tire pressure

Inflate to proper pressure

Tires, wheels or rotors out of balance

Balance tires then check wheels and rotors

Worn or faulty shock absorbers

Check and replace if necessary

Loose tie rod ends or steering

Tighten or replace if necessary

Loose or worn wheel bearings

See SUSPENSION article

Steering Pulls to One Side

Improper tire pressure

Inflate to proper pressure

Front tires are different sizes

Rotate or replace if necessary

Wheel bearings not

adjusted properly

See FRONT SUSPENSION

article

Bent or broken suspension components

See FRONT SUSPENSION

article

Improper wheel alignment

See WHEEL ALIGNMENT

article

Brakes dragging See BRAKES article

pressure

Instability

Low or uneven

tire

Inflate to proper

pressure

Loose or worn wheel See FRONT SUSPENSION
bearings article
Loose or worn idler arm See FRONT SUSPENSION
bushing article
Loose or worn strut See FRONT SUSPENSION
bushings article
Incorrect front wheel See WHEEL ALIGNMENT
alignment article
Steering gear not See MANUAL STEERING
centered GEARS article
Springs or shock Check and replace if necessary
Improper cross shaft See MANUAL STEERING GEARS article

POWER STEERING TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC POWER STEERING TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION Rattle or Pressure hoses touching Adjust to proper

Tighten and check, replace if necessary

fluid

Worn shaft serrations

See STEERING COLUMN

article

Growl in

Steering Pump

Excessive pressure in hoses

Restricted hoses, see POWER STEERING GEAR article

Scored pressure plates

See POWER STEERING GEAR

article

Scored thrust plates or rotor

See POWER STEERING GEAR

article

Extreme wear of cam ring

See POWER

article

STEERING

GEAR

Rattle in

Steering Pump

Vanes not installed

See POWER

article

STEERING

PUMP

Vanes sticking in rotor

See POWER

article

STEERING

PUMP

Swish noise in

Pump

Defective flow control valve

See POWER

article

STEERING

PUMP

Groan in

Steering Pump

Air in fluid

See POWER

article

STEERING

PUMP

Poor pressure hose connection

Squawk When

Turning

Damper “O” ring on spool cut

valve

See POWER STEERING PUMP

article

Moan or Whine

Pump shaft bearing

scored

Replace bearing and

in Pump

Air in fluid or fluid See POWER STEERING PUMP
level low article
Hose or column grounded Check and replace if necessary
Cover “O” ring missing See POWER STEERING PUMP
or damaged article
Valve cover baffle See POWER STEERING PUMP
missing or damaged article
Interference of See POWER STEERING PUMP
components in pump article
Loose or poor bracket Correct or replace if alignment necessary

article

Hissing When

Parking

Internal steering

leakage in gear

Check valved assembly first

Chirp in

Steering Pump

Loose or steering

worn power belt

Adjust or replace if necessary

Buzzing When

Noisy pump

See POWER STEERING PUMP

Not Steering

Free play in steering See STEERING COLUMN
shaft bearing article
Bearing loose on shaft See STEERING COLUMN
serrations article

Clicking Noise in Pump

Pump slippers too long

See POWER

article

STEERING

PUMP

Broken slipper springs

See POWER

article

STEERING

PUMP

Excessive wear or nicked rotors

See POWER

article

STEERING

PUMP

Damaged cam contour

See POWER

article

STEERING

PUMP

Poor Return

Wheel

of

Wheel rubbing against turn signal

See STEERING COLUMN SWITCHES article

Flange rubbing steering gear adjuster

See STEERING COLUMN

article

Tight or frozen steering shaft bearing

See STEERING COLUMN

article

Steering gear out of adjustment

See POWER STEERING GEAR

article

Sticking or plugged spool valve

See POWER STEERING PUMP

article

Improper front end alignment

See WHEEL ALIGNMENT

article

Wheel bearings worn or loose

See FRONT SUSPENSION

article

Ties rods or ball joints binding

Check and replace if necessary

Intermediate shaft joints binding

See STEERING COLUMN

article

Kinked pressure hoses

Correct or replace if necessary

Loose housing head spanner nut

See POWER STEERING GEAR

article

Damaged valve lever

See POWER STEERING GEAR

article

Sector shaft adjusted too tight

See ADJUSTMENTS in POWER STEERING GEAR article

Worm thrust bearing adjusted too tight

See ADJUSTMENTS in POWER STEERING GEAR article

Reaction ring sticking

See POWER STEERING GEAR

in cylinder

article

Reaction ring sticking in housing head

See POWER STEERING GEAR

article

Steering pump internal leakage

See POWER STEERING PUMP

article

Steering gear-to-column misalignment

See STEERING COLUMN

article

Lack of lubrication in linkage

Service front suspension

Lack of lubrication in ball joints

Service front suspension

Increased Effort When Turning Wheel Fast

High internal pump leakage

Power steering pump belt

See POWER STEERING PUMP

article

Adjust or replace if

Foaming, Milky Power Steering Fluid, Low Fluid

slipping

Low fluid level

necessary

Check and fill to

Level or Low

Pressure

Engine idle speed to low

proper level

Adjust to correct

setting

Air in pump fluid system

See POWER STEERING PUMP

article

Pump output low

See POWER STEERING PUMP

article

Steering gear malfunctioning

See POWER STEERING GEAR

article

Wheel Surges or Jerks

Low fluid level

Check and fill to proper level

Loose fan belt

Adjust or replace if necessary

Insufficient pump pressure

See POWER STEERING PUMP

article

Sticky flow control valve

See POWER STEERING PUMP

article

Linkage hitting oil pan at full turn

Replace bent components

Kick Back or

Free Play

Air in pump fluid system

See POWER STEERING PUMP

article

Worn poppet valve in steering gear

See POWER STEERING PUMP

article

Excessive over center lash

See POWER STEERING GEAR

article

Thrust bearing out of

See POWER STEERING GEAR

adjustment

article

Free play in pot coupling See POWER STEERING PUMP
article
Steering gear coupling See POWER STEERING PUMP
loose on shaft article
Steering disc mounting Tighten or replace if bolts loose necessary
Coupling loose on worm Tighten or replace if shaft necessary
Improper sector shaft See POWER STEERING GEAR
adjustment article
Excessive worm piston See POWER STEERING GEAR
side play article
Damaged valve lever See POWER STEERING GEAR
article
Universal joint loose Tighten or replace if necessary

Defective rotary valve

See POWER

article

STEERING

GEAR

No Power

Parking

When

Sticking flow control valve

See POWER

article

STEERING

PUMP

Insufficient pump pressure output

See POWER

article

STEERING

PUMP

Excessive internal pump leakage

See POWER

article

STEERING

PUMP

Excessive internal gear

See POWER

STEERING

PUMP

leakage

article

Flange rubs against gear See STEERING COLUMN
adjust plug article
Loose pump belt Adjust or replace if necessary
Low fluid level Check and add proper amount of fluid
Engine idle too low Adjust to correct setting
Steering gear-to-column See STEERING COLUMN
misaligned article

No Power, Left Turn

Left turn reaction seal

“O” ring worn

See POWER

article

STEERING

GEAR

Left turn reaction seal damaged/missing

See POWER

article

STEERING

GEAR

Cylinder head “O” ring

See POWER

STEERING

PUMP

damaged

article

No Power,

Column pot coupling

See STEERING COLUMN

Right Turns

bottomed

article

Right turn reaction seal See POWER STEERING GEAR “O” ring worn article
Right turn reaction seal See POWER STEERING GEAR
damaged article
Internal leakage through See POWER STEERING GEAR
piston end plug article
Internal leakage through See POWER STEERING GEAR
side plugs article

incorrectarticle

Lack of Effort in Turning

Left and/or right reaction seal sticking in cylinder head

Replace, see POWER STEERING GEAR article

Wanders to

One

Front end alignment

See WHEEL

ALIGNMENT

Side

Unbalanced steering See POWER STEERING GEAR
gear valve article
Low Pressure Due Flow control valve stuck See POWER STEERING PUMP
to Steering Pump or inoperative article
Pressure plate not flat See POWER STEERING PUMP
against cam ring article
Extreme wear of cam ring Replace and check adjustments
Scored plate, thrust See POWER STEERING PUMP
plate or rotor article
Vanes not installed See POWER STEERING PUMP
properly article
Vanes sticking in rotor See POWER STEERING PUMP
slots article
Cracked/broken thrust or See POWER STEERING PUMP
pressure plate article

STEERING COLUMN TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC STEERING COLUMN TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION

article

Noise in

Coupling pulled apart

See STEERING COLUMNS

Steering

Shifting
Improper gate plate See STEERING COLUMN
adjustment article
Excess Play in Instrument panel bracket Tighten bolts and check
Column bolts loose bracket
Broken weld nut on jacket See STEERING COLUMN
article
Instrument bracket capsule See STEERING COLUMN
sheared article
Column bracket/jacket Tighten bolts and check bolts loose bracket
Steering Locks Release lever mechanism See STEERING COLUMN
in Gear article

SUSPENSION TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC SUSPENSION TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Front End Noise Loose or worn wheel See Wheel Bearing Adjustment in SUSPENSION
Worn shocks or shock Replace struts or strut mountings mountings
Worn struts or strut Replace struts or strut mountings mountings
Loose or worn lower control See SUSPENSION
arm
Loose steering gear-to- See STEERING
frame bolts
Worn control arm bushings See SUSPENSION
Ball joints not lubricated Lubricate ball joints & see Ball Joint Checking in SUSPENSION
Front Wheel Tires or wheels out of Check tire balance
Shake, Shimmy, balance or Vibration
Incorrect wheel alignment See WHEEL ALIGNMENT
Drive shaft unbalanced Check drive shaft balance
Loose or worn wheel See WHEEL ALIGNMENT
bearings
Loose or worn tie rod ends See SUSPENSION
Worn upper ball joints See Ball Joint Checking in SUSPENSION
Worn shock absorbers Replace shock absorbers
Worn strut bushings Replace strut bushings
Car Pulls to Mismatched or uneven tires Check tire condition
One Side
Broken or sagging springs See SUSPENSION
Loose or worn strut See SUSPENSION
bushings
Improper wheel alignment See WHEEL ALIGNMENT Improper rear axle Check rear axle
alignment alignment
Power steering gear See STEERING
unbalanced
Front brakes dragging See BRAKES
Abnormal Tire Unbalanced tires Check tire balance & Wear rotation
Sagging or broken springs See SUSPENSION Incorrect front end See WHEEL ALIGNMENT
alignment
Faulty shock absorbers Replace chock absorbers
Scuffed Tires Toe-In incorrect See WHEEL ALIGNMENT Suspension arm bent or See appropriate
twisted SUSPENSION article
Springs Bottom Bent or broken springs See SUSPENSION
or Sag
Leaking or worn shock Replace shock absorbers absorbers
Frame misalignment Check frame for damage

Spring Noises

Loose

“U” Bolts

See

SUSPENSION

Loose

or worn bushings

See

SUSPENSION

Worn or missing interliners

See SUSPENSION

Shock Absorber

Noise

Loose shock mountings

Check & tighten mountings

Worn bushings

Replace bushings

Car Leans or

Air in system

Undercoating on shocks

Loose stabilizer bar

Bleed air from system

Remove undercoating

See SUSPENSION

Sways on Corners

Faulty shocks or mountings

Replace shocks or mountings

Broken or sagging springs

See SUSPENSION

Shock Absorbers

Leaking

Worn seals or reservoir tube crimped

See SUSPENSION

Broken Springs

Loose “U” bolts

See SUSPENSION

Inoperative shock absorbers

Replace shock absorbers

WHEEL ALIGNMENT TROUBLE SHOOTING

NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC WHEEL ALIGNMENT TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE CORRECTION
Premature Tire Improper tire inflation Check tire pressure
Wear
Front alignment out of See ALIGNMENT SPECS in tolerance WHEEL ALIGNMENT section
Suspension components worn See SUSPENSION section
Steering system components See STEERING section worn
Improper standing height See WHEEL ALIGNMENT Uneven or sagging springs See SUSPENSION section Bent wheel See WHEEL ALIGNMENT Improper torsion bar See SUSPENSION section
adjustment
Loose or worn wheel See WHEEL BEARING ADJ. bearings in SUSPENSION section
Worn or defective shock Replace shock absorbers
Tires out of balance Check tire balance
Pulls to One Improper tire inflation Check tire pressure
Side
Brake dragging See BRAKE section
Mismatched tires See WHEEL ALIGNMENT Broken or sagging spring See SUSPENSION section Broken torsion bar See SUSPENSION section
Power steering valve not See STEERING section centered
Front alignment out of See WHEEL ALIGNMENT
tolerance section
Defective wheel bearing See WHEEL BEARINGS in
SUSPENSION section
Uneven sway bar links See SUSPENSION section Frame bent Check for frame damage Steering system bushing See STEERING section
worn
Hard Steering Idler arm bushing too tight See STEERING LINKAGE
in STEERING section
Ball joint tight or seized See SUSPENSION section
Steering linkage too tight See STEERING LINKAGE in
STEERING section
Power steering fluid low Add proper amount of fluid
Power steering drive belt See STEERING section loose
Power steering pump See STEERING section defective
Steering gear out of See STEERING section adjustment

Incorrect wheel alignment

See

WHEEL ALIGNMENT

Damaged steering gear

See

STEERING section

Damaged suspension

See

SUSPENSION section

Bent steering knuckle or supports

See

SUSPENSION section

Vehicle

“Wanders”

Strut rod or control arm bushing worn

See

SUSPENSION section

Loose or worn wheel

See

WHEEL BEARINGS in

bearings SUSPENSION section
Improper tire inflation Check tire pressure
Stabilizer bar missing or See SUSPENSION section defective
Wheel alignment out of See Adjustment in tolerance WHEEL ALIGNMENT section
Broken spring See SUSPENSION section Defective shock absorbers Replace shock absorbers Worn steering & suspension See SUSPENSION section
components
Front End Shimmy Tire out of balance/round Check tire balance Excessive wheel runout See WHEEL ALIGNMENT Insufficient or improper See WHEEL ALIGNMENT
caster section
Worn suspension or steering See SUSPENSION section components
Defective shock absorbers Replace shock absorber
Wheel bearings worn or See WHEEL BEARING ADJ. loose in SUSPENSION section
Power steering reaction See STEERING section
Bracket loose
Steering gear box (rack) See STEERING section mounting loose
Steering gear adjustment See STEERING section loose
Worn spherical joints See SUSPENSION section
Toe-In Not Lower control arm bent See SUSPENSION section
Adjustable
Frame bent Check frame for damage
Camber Not Control arm bent See SUSPENSION section
Adjustable
Frame bent Check frame for damage
Hub & bearing not seated See SUSPENSION section properly

 

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