engine JEEP CHEROKEE 1988 Service Repair Manual
[x] Cancel search | Manufacturer: JEEP, Model Year: 1988, Model line: CHEROKEE, Model: JEEP CHEROKEE 1988Pages: 1378, PDF Size: 19.9 MB
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 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 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 1273 of 1378
![JEEP CHEROKEE 1988 Service Repair Manual Brakes dragging See BRAKES article \
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Brakes dragging See BRAKES article \
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Instability Low or uneven tire Inflate to proper
pressure 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
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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
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CONDITION POSSIBLE CAUSE CORRECTION \
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Rattle or Pressure hoses touching Adjust to proper
Chucking Noise engine parts clearance
Loose Pitman shaft Adjust or replace if
necessary
Tie rods ends or Pitman Tighten and check system
arm loose
Rack and pinion mounts Tighten all mounting
loose bolts
Free play in worm and See POWER STEERING GEAR
article
Loose sector shaft or See POWER STEERING GEAR
thrust bearing adjustment
Free play in pot coupling See STEERING COLUMN
article
Page 1276 of 1378
Reaction ring sticking See POWER STEERING GEAR
in housing head article
Steering pump internal See POWER STEERING PUMP
leakage article
Steering gear-to-column See STEERING COLUMN
misalignment article
Lack of lubrication in Service front suspension
linkage
Lack of lubrication in Service front suspension
ball joints
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Increased Effort High internal pump leakage See POWER STEERING PUMP
When Turning article
Wheel Fast Power steering pump belt Adjust or replace if
Foaming, Milky slipping necessary
Power Steering
Fluid, Low Fluid Low fluid level Check and fill to
Level or Low proper level
Pressure
Engine idle speed to low Adjust to correct
setting
Air in pump fluid system See POWER STEERING PUMP
article
Pump output low See POWER STEERING PUMP
article
Steering gear See POWER STEERING GEAR
malfunctioning article
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Wheel Surges Low fluid level Check and fill to proper
or Jerks level
Loose fan belt Adjust or replace if
necessary
Insufficient pump See POWER STEERING PUMP
pressure article
Sticky flow control valve See POWER STEERING PUMP
article
Linkage hitting oil pan Replace bent components
at full turn
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Kick Back or Air in pump fluid system See POWER STEERING PUMP
Free Play article
Worn poppet valve in See POWER STEERING PUMP
steering gear article
Excessive over center See POWER STEERING GEAR
lash article
Thrust bearing out of See POWER STEERING GEAR
adjustment article
Page 1277 of 1378
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 STEERING GEAR
article
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No Power When Sticking flow control See POWER STEERING PUMP
Parking valve article
Insufficient pump See POWER STEERING PUMP
pressure output article
Excessive internal pump See POWER STEERING PUMP
leakage article
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
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No Power, Left turn reaction seal See POWER STEERING GEAR
Left Turn "O" ring worn article
Left turn reaction seal See POWER STEERING GEAR
damaged/missing article
Cylinder head "O" ring See POWER STEERING PUMP
damaged article
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\003
TU NE-U P - 4 -C YL
1988 J e ep C hero ke e
1988 Jeep 4 Tune-Up
TUNE-UP
All Models
IDENTIFICATION
ENGINE IDENTIFICATION
Engine can be identified by the 4th character of the Vehicle
Identification Number (VIN). The VIN is stamped on a plate attached to\
top left corner of instrument panel.
ENGINE CODES
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Engine Code
2.5L (150") TBI .................................................. H\
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TUNE-UP NOTES
NOTE: When performing tune-up procedures described in this
article, the following notes and precautions must be
followed.
Due to late changes and corrections, always refer to Emission
Control Label in engine compartment before attempting tune-up. If
manual and label differ, always use label specifications.
EPA High Altitude emission standards apply to vehicles sold
in certain areas outside California which have an elevation above 4000
feet.
When performing tune-up on vehicles equipped with catalytic
converter, do not allow or create an engine misfire in one or more
cylinders for an extended period of time. Damage to converter may
occur due to loading converter with unburned fuel.
TESTING
ENGINE COMPRESSION
Test compression with all spark plugs removed, throttle
plates and choke valve wide open and engine at normal operating
temperature. Crank engine through at least 5 compression strokes
before recording reading.
COMPRESSION SPECIFICATIONS
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Application Specification
Compression Ratio ............................................ 9.2:1
Compression Pressure ................ 155-185 psi (10.9-13.0 kg/cm
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Max. Variation Between Cylinders ............... 30 psi (2.1 kg/cm) \
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SPARK PLUGS
SPARK PLUG TYPE