2002 JEEP LIBERTY Engine repair

FOREWORD
This manual is designed as a supplement to be used along with the 2002 Liberty service manual,
81-370-02060. It includes information related to the 2.4L gas engine installed in this vehicle by
DaimlerChrysler Corporation. For diagnosis or service procedures relating to other components or systems,
refer to the 2002 Liberty Service Manual.
The information contained in this service manual has been prepared for the professional automotive tech-
nician involved in daily repair operations. Information describing the operation and use of standard and
optional equipment is included in the Owner's Manual provided with the vehicle.
Information in this manual is divided into groups. These groups contain description, operation, diagnosis,
testing, adjustments, removal, installation, disassembly, and assembly procedures for the systems and compo-
nents. To assist in locating a group title page, use the Group Tab Locator on the following page. The solid bar
after the group title is aligned to a solid tab on the first page of each group. The first page of the group has
a contents section that lists major topics within the group. If you are not sure which Group contains the infor-
mation you need, look up the Component/System in the alphabetical index located in the rear of this manual.
A Service Manual Comment form is included at the rear of this manual. Use the form to provide
DaimlerChrysler Corporation with your comments and suggestions.
Tightening torques are provided as a specific value throughout this manual. This value represents the
midpoint of the acceptable engineering torque range for a given fastener application. These torque values are
intended for use in service assembly and installation procedures using the correct OEM fasteners. When
replacing fasteners, always use the same type (part number) fastener as removed.
DaimlerChrysler Corporation reserves the right to change testing procedures, specifications, diagnosis,
repair methods, or vehicle wiring at any time without prior notice or incurring obligation.

FASTENER USAGE
DESCRIPTION
DESCRIPTION
WARNING: USE OF AN INCORRECT FASTENER
MAY RESULT IN COMPONENT DAMAGE OR PER-
SONAL INJURY.
Figure art, specifications and torque references in
this Service Manual are identified in metric and SAE
format.
During any maintenance or repair procedures, it is
important to salvage all fasteners (nuts, bolts, etc.)
for reassembly. If the fastener is not salvageable, a
fastener of equivalent specification must be used.
DESCRIPTION
Most stripped threaded holes can be repaired using
a Helicoilt. Follow the vehicle or Helicoiltrecommen-
dations for application and repair procedures.
THREADED HOLE REPAIR
DESCRIPTION
Most stripped threaded holes can be repaired using
a Helicoilt. Follow the vehicle or Helicoiltrecommen-
dations for application and repair procedures.
INTERNATIONAL SYMBOLS
DESCRIPTION
The graphic symbols illustrated in the following
International Control and Display Symbols Chart
(Fig. 3) are used to identify various instrument con-
trols. The symbols correspond to the controls and dis-
plays that are located on the instrument panel.
Fig. 3 INTERNATIONAL CONTROL AND DISPLAY SYMBOLS
1 High Beam 13 Rear Window Washer
2 Fog Lamps 14 Fuel
3 Headlamp, Parking Lamps, Panel Lamps 15 Engine Coolant Temperature
4 Turn Warning 16 Battery Charging Condition
5 Hazard Warning 17 Engine Oil
6 Windshield Washer 18 Seat Belt
7 Windshield Wiper 19 Brake Failure
8 Windshield Wiper and Washer 20 Parking Brake
9 Windscreen Demisting and Defrosting 21 Front Hood
10 Ventilating Fan 22 Rear hood (Decklid)
11 Rear Window Defogger 23 Horn
12 Rear Window Wiper 24 Lighter
4 INTRODUCTIONKJ

API QUALITY CLASSIFICATION
This symbol (Fig. 2) on the front of an oil container
means that the oil has been certified by the Ameri-
can Petroleum Institute (API) to meet all the lubri-
cation requirements specified by DaimlerChrysler
Corporation.
GEAR LUBRICANTS
SAE ratings also apply to multigrade gear lubri-
cants. In addition, API classification defines the
lubricants usage. Such as API GL-5 and SAE 75W-
90.
LUBRICANTS AND GREASES
Lubricating grease is rated for quality and usage
by the NLGI. All approved products have the NLGI
symbol (Fig. 3) on the label. At the bottom NLGI
symbol is the usage and quality identification letters.
Wheel bearing lubricant is identified by the letter
ªGº. Chassis lubricant is identified by the latter ªLº.
The letter following the usage letter indicates the
quality of the lubricant. The following symbols indi-
cate the highest quality.
SPECIALIZED LUBRICANTS AND OILS
Some maintenance or repair procedures may
require the use of specialized lubricants or oils. Con-
sult the appropriate sections in this manual for the
correct application of these lubricants.
DESCRIPTION - AXLE
A multi-purpose, hypoid gear lubricant which con-
forms to MIL-L-2105C and API GL 5 quality specifi-
cations should be used. Mopar Hypoid Gear
Lubricants conforms to these specifications.
FRONT AXLE
²Lubricant for 186FIA (Model 30) axle is SAE
75W-140 SYNTHETIC.
REAR AXLE
²Lubricant for 198RBI (Model 35) axle is SAE
75W-140 SYNTHETIC.
²Lubricant for 8 1/4 axle is a thermally stable
SAE 75W-90. For trailer tow or heavy duty applica-
tions the lubricant should be replaced with SAE
75W-140 SYNTHETIC.
NOTE: Trac-lokTequipped axles require a friction
modifier be added to the lubricant.
CAUTION: If axle is submerged in water, lubricant
must be replaced immediately to avoid possible
premature axle failure.
DESCRIPTION - MANUAL TRANSMISSION
Mopartmanual transmission fluid is the lubricant
recommended for the NV1500 and the NV3550 trans-
missions.
DESCRIPTION - AUTOMATIC TRANSMISSION
FLUID
NOTE: Refer to the maintenance schedules in this
group for the recommended maintenance (fluid/filter
change) intervals for this transmission.
NOTE: Refer to Service Procedures in this group for
fluid level checking procedures.
MopartATF +4, type 9602, Automatic Transmis-
sion Fluid is the recommended fluid for
DaimlerChrysler automatic transmissions.
Dexron II fluid IS NOT recommended. Clutch
chatter can result from the use of improper
fluid.
MopartATF +4, type 9602, Automatic Transmis-
sion Fluid when new is red in color. The ATF is dyed
red so it can be identified from other fluids used in
the vehicle such as engine oil or antifreeze. The red
color is not permanent and is not an indicator of fluid
condition. As the vehicle is driven, the ATF will begin
to look darker in color and may eventually become
brown.This is normal.ATF+4 also has a unique
Fig. 2 API Symbol
Fig. 3 NLGI Symbol
1 - WHEEL BEARINGS
2 - CHASSIS LUBRICATION
3 - CHASSIS AND WHEEL BEARINGS
0 - 2 LUBRICATION & MAINTENANCEKJ
FLUID TYPES (Continued)

DRIVELINE VIBRATION
Drive Condition Possible Cause Correction
Propeller Shaft Noise 1. Undercoating or other foreign
material on shaft.1. Clean exterior of shaft and wash
with solvent.
2. Loose U-joint clamp screws. 2. Install new clamps and screws
and tighten to proper torque.
3. Loose or bent U-joint yoke or
excessive runout.3. Install new yoke.
4. Incorrect driveline angularity. 4. Measure and correct driveline
angles.
5. Worn joint. 5. Install new joint.
6. Propeller shaft damaged or out
of balance.6. Installl new propeller shaft.
7. Broken rear spring. 7. Install new rear spring.
8. Excessive runout or unbalanced
condition.8. Re-index propeller shaft, test, and
evaluate.
9. Excessive drive pinion gear shaft
runout.9. Re-index propeller shaft and
evaluate.
10. Excessive axle yoke deflection. 10. Inspect and replace yoke if
necessary.
11. Excessive transfer case runout. 11. Inspect and repair as necessary.
Joint Noise 1. Loose U-joint clamp screws. 1. Install new clamps and screws
and tighten to proper torque.
2. Lack of lubrication. 2. Replace joints as necessary.
BALANCE
NOTE: Removing and re-indexing the propeller
shaft 180É relative to the yoke may eliminate some
vibrations.
If propeller shaft is suspected of being unbalanced,
it can be verified with the following procedure:
(1) Raise the vehicle.
(2) Clean all the foreign material from the propel-
ler shaft and the universal joints.
(3) Inspect the propeller shaft for missing balance
weights, broken welds, and bent areas.If the pro-
peller shaft is bent, it must be replaced.
(4) Inspect the universal joints to ensure that they
are not worn, are properly installed, and are cor-
rectly aligned with the shaft.
(5) Check the universal joint clamp screws torque.
(6) Remove the wheels and tires. Install the wheel
lug nuts to retain the brake drums or rotors.
(7) Mark and number the shaft six inches from the
yoke end at four positions 90É apart.
(8) Run and accelerate the vehicle until vibration
occurs. Note the intensity and speed the vibration
occurred. Stop the engine.(9) Install a screw clamp at position 1 (Fig. 1).
Fig. 1 CLAMP AT POSITION 1
1 - CLAMP
2 - SCREWDRIVER
3 - 2 PROPELLER SHAFTKJ
PROPELLER SHAFT (Continued)

When turning corners, the outside wheel must
travel a greater distance than the inside wheel to
complete a turn. The difference must be compensated
for to prevent the tires from scuffing and skidding
through turns. To accomplish this, the differential
allows the axle shafts to turn at unequal speeds (Fig.
2). In this instance, the input torque applied to the
pinion gears is not divided equally. The pinion gears
now rotate around the pinion mate shaft in opposite
directions. This allows the side gear and axle shaft
attached to the outside wheel to rotate at a faster
speed.
DIAGNOSIS AND TESTING - AXLE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, tooth contact, worn/damaged
gears or the carrier housing not having the proper
offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
peak-noise range. If the noise stops or changes
greatly:
²Check for insufficient lubricant.
²Incorrect ring gear backlash.
²Gear damage.
Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehi-cle turns. A worn pinion mate shaft can also cause a
snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.
Pinion bearings have a constant-pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
heard during a coast, the front pinion bearing is the
source.
Worn or damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differen-
tial bearing noise is also constant and varies only
with vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U-joint or by worn side-gear thrust washers. A worn
pinion shaft bore will also cause low speed knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by:
²Damaged drive shaft.
²Missing drive shaft balance weight(s).
²Worn or out of balance wheels.
²Loose wheel lug nuts.
²Worn U-joint(s).
²Loose/broken springs.
²Damaged axle shaft bearing(s).
²Loose pinion gear nut.
²Excessive pinion yoke run out.
²Bent axle shaft(s).
Check for loose or damaged front end components
or engine/transmission mounts. These components
can contribute to what appears to be a rear end
vibration. Do not overlook engine accessories, brack-
ets and drive belts.
All driveline components should be examined
before starting any repair.
Fig. 2 DIFFERENTIAL-ON TURNS
1 - PINION GEARS ROTATE ON PINION SHAFT
3 - 20 FRONT AXLE - 186FIAKJ
FRONT AXLE - 186FIA (Continued)

DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged) can be caused by:
²High engine idle speed.
²Transmission shift operation.
²Loose engine/transmission/transfer case mounts.
²Worn U-joints.
²Loose spring mounts.
²Loose pinion gear nut and yoke.²Excessive ring gear backlash.
²Excessive side gear to case clearance.
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the vehi-
cle on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listen
for the noise, a mechanics stethoscope is helpful in
isolating the source of a noise.
DIAGNOSTIC CHART
Condition Possible Causes Correction
Wheel Noise 1. Wheel loose. 1. Tighten loose nuts.
2. Faulty, brinelled wheel bearing. 2. Replace bearing.
Axle Shaft Noise 1. Misaligned axle tube. 1. Inspect axle tube alignment.
Correct as necessary.
2. Bent or sprung axle shaft. 2. Inspect and correct as necessary.
3. End-play in pinion bearings. 3. Refer to pinion pre-load
information and correct as
necessary.
4. Excessive gear backlash
between the ring gear and pinion.4. Check adjustment of the ring
gear and pinion backlash. Correct
as necessary.
5. Improper adjustment of pinion
gear bearings.5. Adjust the pinion bearings
pre-load.
6. Loose pinion yoke nut. 6. Tighten the pinion yoke nut.
7. Scuffed gear tooth contact
surfaces.7. Inspect and replace as
necessary.
Axle Shaft Broke 1. Misaligned axle tube. 1. Replace the broken shaft after
correcting tube mis-alignment.
2 Vehicle overloaded. 2. Replace broken shaft and avoid
excessive weight on vehicle.
3. Erratic clutch operation. 3. Replace broken shaft and avoid
or correct erratic clutch operation.
4. Grabbing clutch. 4. Replace broken shaft and inspect
and repair clutch as necessary.
KJFRONT AXLE - 186FIA 3 - 21
FRONT AXLE - 186FIA (Continued)

The Trac-lokŸ design provides the differential
action needed for turning corners and for driving
straight ahead during periods of unequal traction.
When one wheel looses traction, the clutch packs
transfer additional torque to the wheel having the
most traction. Trac-lokŸ differentials resist wheel
spin on bumpy roads and provide more pulling power
when one wheel looses traction. Pulling power is pro-
vided continuously until both wheels loose traction. If
both wheels slip due to unequal traction, Trac-lokŸ
operation is normal. In extreme cases of differences
of traction, the wheel with the least traction may
spin.
DIAGNOSIS AND TESTING - AXLE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant, incorrect backlash, incorrect pinion depth, tooth
contact, worn/damaged gears, or the carrier housing
not having the proper offset and squareness.
Gear noise usually happens at a specific speed
range. The noise can also occur during a specific type
of driving condition. These conditions are accelera-
tion, deceleration, coast, or constant load.
When road testing, first warm-up the axle fluid by
driving the vehicle at least 5 miles and then acceler-
ate the vehicle to the speed range where the noise is
the greatest. Shift out-of-gear and coast through the
peak-noise range. If the noise stops or changes
greatly:
²Check for insufficient lubricant.
²Incorrect ring gear backlash.
²Gear damage.
Differential side gears and pinions can be checked
by turning the vehicle. They usually do not cause
noise during straight-ahead driving when the gears
are unloaded. The side gears are loaded during vehi-
cle turns. A worn pinion shaft can also cause a snap-
ping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion bearings can
all produce noise when worn or damaged. Bearing
noise can be either a whining, or a growling sound.
Pinion bearings have a constant-pitch noise. This
noise changes only with vehicle speed. Pinion bearing
noise will be higher pitched because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs, the rear pinion bearing
is the source of the noise. If the bearing noise is
heard during a coast, the front pinion bearing is the
source.
Worn or damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing noise. The pitch of differen-tial bearing noise is also constant and varies only
with vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
LOW SPEED KNOCK
Low speed knock is generally caused by a worn
U-joint or by worn side±gear thrust washers. A worn
pinion shaft bore will also cause low speed knock.
VIBRATION
Vibration at the rear of the vehicle is usually
caused by a:
²Damaged drive shaft.
²Missing drive shaft balance weight(s).
²Worn or out-of-balance wheels.
²Loose wheel lug nuts.
²Worn U-joint(s).
²Loose/broken springs.
²Damaged axle shaft bearing(s).
²Loose pinion gear nut.
²Excessive pinion yoke run out.
²Bent axle shaft(s).
Check for loose or damaged front-end components
or engine/transmission mounts. These components
can contribute to what appears to be a rearend vibra-
tion. Do not overlook engine accessories, brackets
and drive belts.
NOTE: All driveline components should be exam-
ined before starting any repair.
DRIVELINE SNAP
A snap or clunk noise when the vehicle is shifted
into gear (or the clutch engaged), can be caused by:
²High engine idle speed.
²Transmission shift operation.
²Loose engine/transmission/transfer case mounts.
²Worn U-joints.
²Loose spring mounts.
²Loose pinion gear nut and yoke.
²Excessive ring gear backlash.
²Excessive side gear to case clearance.
The source of a snap or a clunk noise can be deter-
mined with the assistance of a helper. Raise the vehi-
cle on a hoist with the wheels free to rotate. Instruct
the helper to shift the transmission into gear. Listen
for the noise, a mechanics stethoscope is helpful in
isolating the source of a noise.
KJREAR AXLE - 198RBI 3 - 51
REAR AXLE - 198RBI (Continued)

(6) Install the bearing caps in their original loca-
tions (Fig. 50).
(7) Loosely install differential bearing cap bolts.
(8) Remove axle housing spreader.
(9) Tighten the bearing cap bolts to 64-91 N´m
(47-67 ft. lbs.).
(10) Install the axle shafts.
(11) Apply a 6.35mm (1/4 in.) bead of red Mopar
Silicone Rubber Sealant or equivalent to the housing
cover (Fig. 51).
CAUTION: If cover is not installed within 3 to 5 min-
utes, the cover must be cleaned and new RTV
applied or adhesion quality will be compromised.
(12) Install the cover and tighten cover bolts in a
criss-cross pattern to 38-45 N´m (28-33 ft. lbs.).
(13) Refill the differential with lubricant and
install fill plug.
(14) Remove support and lower the vehicle.
DIFFERENTIAL - TRAC-LOK
DIAGNOSIS AND TESTING - TRAC-LOKT
The most common problem is a chatter noise when
turning corners. Before removing the unit for repair,
drain, flush and refill the axle with the specified
lubricant. A container of Mopar Trac-loktLubricant
(friction modifier) should be added after repair ser-
vice or during a lubricant change.
After changing the lubricant, drive the vehicle and
make 10 to 12 slow, figure-eight turns. This maneu-
ver will pump lubricant through the clutches. This
will correct the condition in most instances. If the
chatter persists, clutch damage could have occurred.
DIFFERENTIAL TEST
The differential can be tested without removing the
differential case by measuring rotating torque. Make
sure brakes are not dragging during this measure-
ment.
(1) Place blocks in front and rear of both front
wheels.
(2) Raise one rear wheel until it is completely off
the ground.
(3) Engine off, transmission in neutral, and park-
ing brake off.
(4) Remove wheel and bolt Special Tool 6790 or
equivalent tool to studs.
(5) Use torque wrench on special tool to rotate
wheel and read rotating torque (Fig. 52).
(6) If rotating torque is less than 41 N´m (56 ft.
lbs.) or more than 271 N´m (200 ft. lbs.) on either
wheel the unit should be serviced.
Fig. 50 BEARING CAP REFERENCE
1 - REFERENCE LETTERS
2 - REFERENCE LETTERS
Fig. 51 DIFFERENTIAL COVER - TYPICAL
1 - SEALING SURFACE
2 - SEALANT BEAD
3 - SEALANT THICKNESS
3 - 74 REAR AXLE - 198RBIKJ
DIFFERENTIAL (Continued)