JEEP CHEROKEE 1988 Service Repair Manual
Manufacturer: JEEP, Model Year: 1988, Model line: CHEROKEE, Model: JEEP CHEROKEE 1988Pages: 1378, PDF Size: 19.9 MB
Page 1261 of 1378
Vacuum leak Repair vacuum leak
Improper float bowl fuel Reset float
level adjustment, see FUEL
Clogged air bleed or idle Clean carburetor
passages passages, see FUEL
Clogged or worn air cleaner Replace air filter
filter
Faulty choke vacuum Replace diaphragm,
diaphragm see ENGINE PERFORMANCE
Exhaust manifold heat valve Replace heat valve
inoperative
Improper distributor spark Check distributor
advance operation
Leaking valves or valve Check and repair
components valvetrain
Improper carburetor Remove and remount
mounting carburetor
Excessive play in Replace distributor
distributor shaft
Loose or corroded wiring Repair or replace as
connections required
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Engine Surges Improper PCV valve airflow Replace PCV valve
Vacuum leaks Repair vacuum leaks
Clogged air bleeds Remove restriction
EGR valve malfunction Replace EGR valve
Restricted air cleaner Replace air filter
filter
Cracked or broken vacuum Replace vacuum hoses
hoses
Cracked or broken ignition Replace ignition
wires wires
Vacuum advance malfunction Check unit and
replace as necessary
Defective or fouled spark Replace spark plugs
plugs
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Ping or Spark Incorrect ignition timing Reset ignition timing
Knock see ENGINE PERFORMANCE
Distributor centrifugal or Check operation and
vacuum advance malfunction replace as necessary
Carburetor setting too lean Readjust mixture
Page 1262 of 1378
setting, see ENGINE
PERFORMANCE
Vacuum leak Eliminate vacuum leak
EGR valve malfunction Replace EGR valve
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Poor Gasoline Cracked or broken vacuum Replace vacuum hoses
Mileage 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 Eliminate binding
piston
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
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Engine Stalls Improper float level Readjust float level
Leaking needle valve and Replace needle valve
seat and seat
Vacuum leaks Eliminate vacuum
leaks
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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
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CONDITION POSSIBLE CAUSE CORRECTION \
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Page 1263 of 1378
Excessive Noise Loose pump-to-drive Tighten screws
assembly screws
Loose tube on pump assembly Tighten tube
Valves not functioning Replace valves
properly
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Oil Leakage Loose end plug Tighten end plug
Bad seal crimp Remove and re-crimp
seal
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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
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Condition Possible Cause \
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Noisy In Forward Gears .Low gear oil level,
.Loose bell housing bolts,
.Worn bearings or gears
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Clunk On Deceleration
(FWD Only) .Loose engine mounts,
.Worn inboard CV joints,
.Worn differential pinion shaft,
.Side gear hub counterbore
in case worn oversize
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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
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Transmission Noisy When
Moving (RWD Only) Quiet In
Neutral With Clutch Engaged .Worn rear outputshaft bearing
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Gear Rattle .Worn bearings,
.Wrong gear oil,
.Low gear oil,
.Worn gears
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Steady Ticking At Idle
(Increases With RPM) .Broken tooth on gear
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Gear Clash When Shifting
Forward Gears .Worn or broken synchronizers
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Loud Whine In Reverse .Normal condition ( 1) \
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Page 1264 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual Noise When Stepping On Clutch .Bad release bearing,
.Worn pilot bearing
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.Worn pilot bearing
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Noise When Stepping On Clutch .Bad release bearing,
.Worn pilot bearing
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Ticking Or Screeching As
Clutch Is Engaged .Faulty release bearing,
.Uneven pressure plate fingers
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Click Or Snap When Clutch
Is Engaged .Worn clutch fork,
.Worn or broken front bearing
retainer
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Transmission Shifts Hard .Clutch not releasing,
.Shift mechanism binding,
.Clutch installed backwards
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Will Not Shift Into One
Gear, Shifts Into All
Others .Bent shift fork,
.Worn detent balls
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Locked Into Gear,
Cannot Shift .Clutch adjustment,
.Worn detent balls
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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
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Shift Lever Rattle .Worn shift lever or detents
.Worn shift forks
.Worn synchronizers sleeve
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Shift Lever Hops Under
Acceleration .Worn engine or transmission
mounts
( 1) - Most units use spur cut gears in reverse and are noisy
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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
Page 1265 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual \
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CONDITION POSSIBLE CAUSE](/img/16/57037/w960_57037-1264.png "JEEP CHEROKEE 1988 Service Repair Manual \
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CONDITION POSSIBLE CAUSE")
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CONDITION POSSIBLE CAUSE CORRECTION \
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Chattering or Incorrect clutch adjustment Adjust clutch
Grabbing
Oil, grease or glaze on Disassemble and clean
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 Replace worn/misaligned
contact components
Loose/bent clutch disc Replace clutch disc
Incorrect transmission Realign transmission
alignment
Worn pressure plate, disc Replace damaged
or flywheel components
Broken or weak pressure Replace pressure
springs plate
Sticking clutch pedal Lubricate clutch pedal
& linkage
Incorrect clutch disc Replace clutch disc
facing
Engine loose in chassis Tighten all mounting
bolts
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Failure to Oil or grease on clutch Clean or replace clutch
Release facings clutch disc
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
Page 1266 of 1378
Defective clutch master Replace master cylinder
Defective clutch slave Replace slave cylinder
Air in hydraulic system Bleed hydraulic system
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Rattling Weak or broken release Replace spring and
lever spring check alignment
Damaged pressure plate Replace pressure plate
Broken clutch return spring Replace return spring
Worn splines on clutch disc Replace clutch disc
or input shaft and/or input shaft
Worn clutch release bearing Replace release bearing
Dry or worn pilot bearing Lubricate or replace
pilot bearing
Unequal release lever Align or replace
contact release lever
Incorrect pedal free play Adjust free play
Warped or damaged clutch Replace damaged
disc components
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Slipping Pressure springs worn or Release pressure plate
Oily, greasy or worn Clean or replace clutch
facings disc
Incorrect clutch alignment Realign clutch assembly
Warped clutch disc or Replace damaged
pressure plate components
Binding release levers or Lubricate and/or
clutch pedal replace release
components
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Squeaking Worn or damaged release Replace release bearing
Dry or worn pilot or Lubricate or replace
release bearing assembly
Pilot bearing turning in Replace pilot bearing
crankshaft and/or crankshaft
Worn input shaft bearing Replace bearing and
seal
Incorrect transmission Realign transmission
alignment
Dry release fork between Lubricate release fork
pivot and pivot
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Heavy and/or Sticking release bearing Replace release bearing
Stiff Pedal sleeve and/or sleeve
Page 1267 of 1378
Dry or binding clutch Lubricate and align
pedal hub components
Floor mat interference Lay mat flat in proper
with pedal area
Dry or binding ball/fork Lubricate and align
pivots components
Faulty clutch cable Replace clutch cable
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Noisy Clutch Faulty interlock switch Replace interlock
Pedal switch
Self-adjuster ratchet Lubricate or replace
noise self-adjuster
Speed control interlock Lubricate or replace
switch interlock switch
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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
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Noisy Dry release bearing Lubricate or replace
release bearing
Dry or worn pilot bearing Lubricate or replace
bearing
Worn input shaft bearing Replace bearing
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Transmission Weak springs in pressure Replace pressure plate
Click plate
Release fork loose on ball Replace release fork
stud and/or ball stud
Oil on clutch disc damper Replace clutch disc
Broken spring in slave Replace slave cylinder
cylinder
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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.
Page 1268 of 1378
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
Page 1269 of 1378
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
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CONDITION POSSIBLE CAUSE CORRECTION
Page 1270 of 1378
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Knocking or Clunking
Differe](/img/16/57037/w960_57037-1269.png "JEEP CHEROKEE 1988 Service Repair Manual \
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Knocking or Clunking
Differe")
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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
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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
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Click/Chatter On Turns
Differential Side Gear
Clearance Check Clearance
Wrong Turn On Plates (1) Replace Clutch Plates
Wrong Differential
Lubricant ( 1) Change Lubricant
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Knock Or Click Flat Spot on Rear
Wheel Bearing Replace Wheel Bearing
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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.
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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