2002 JEEP GRAND CHEROKEE Fuel

CATALYTIC CONVERTER - 4.7L
DESCRIPTION - CATALYTIC CONVERTER
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER WORK AROUND OR ATTEMPT
TO SERVICE ANY PART OF THE EXHAUST SYSTEM
UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE
TAKEN WHEN WORKING NEAR THE CATALYTIC
CONVERTER. THE TEMPERATURE OF THE CON-
VERTER RISES TO A HIGH LEVEL AFTER A SHORT
PERIOD OF ENGINE OPERATION TIME.
CAUTION: DO NOT remove spark plug wires from
plugs or by any other means short out cylinders.
Failure of the catalytic converter can occur due to a
temperature increase caused by unburned fuel
passing through the converter.The stainless steel catalytic converter body is
designed to last the life of the vehicle. Excessive heat
can result in bulging or other distortion, but exces-
sive heat will not be the fault of the converter. If
unburned fuel enters the converter, overheating may
occur. If a converter is heat-damaged, correct the
cause of the damage at the same time the converter
is replaced. Also, inspect all other components of the
exhaust system for heat damage.
Unleaded gasoline must be used to avoid con-
taminating the catalyst core.
50 State emission vehicles incorporate two mini
catalytic converters located after the exhaust mani-
folds and before the inline catalytic converter (Fig. 6).
REMOVAL
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
Fig. 6 4.7L Catalytic Converter and O2 Sensor Configuration - 50 State Emissions
11 - 6 EXHAUST SYSTEMWJ

EXHAUST PIPE - 4.0L
REMOVAL
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER WORK AROUND OR ATTEMPT
TO SERVICE ANY PART OF THE EXHAUST SYSTEM
UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE
TAKEN WHEN WORKING NEAR THE CATALYTIC
CONVERTER. THE TEMPERATURE OF THE CON-
VERTER RISES TO A HIGH LEVEL AFTER A SHORT
PERIOD OF ENGINE OPERATION TIME.
(1) Raise and support the vehicle.(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.
(3) Remove the oxygen sensor from the exhaust
pipe (Fig. 9).
(4) Remove the nuts from the exhaust pipe to cat-
alytic converter flange connection (Fig. 10).
(5) Disconnect the exhaust pipe from the exhaust
manifold (Fig. 11).
INSPECTION
Discard rusted clamps, broken or worn supports
and attaching parts. Replace a component with orig-
inal equipment parts, or equivalent. This will assure
proper alignment with other parts in the system and
provide acceptable exhaust noise levels.
INSTALLATION
(1) Connect the exhaust pipe to the engine exhaust
manifold. Tighten the nuts to 31 N´m (23 ft. lbs.)
(Fig. 11).
Fig. 9 O2 Sensor Location 4.0L
11 - 8 EXHAUST SYSTEMWJ

EXHAUST PIPE - 4.7L
REMOVAL
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER WORK AROUND OR ATTEMPT
TO SERVICE ANY PART OF THE EXHAUST SYSTEM
UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE
TAKEN WHEN WORKING NEAR THE CATALYTIC
CONVERTER. THE TEMPERATURE OF THE CON-
VERTER RISES TO A HIGH LEVEL AFTER A SHORT
PERIOD OF ENGINE OPERATION TIME.
(1) Raise and support the vehicle.(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.
(3) Remove the oxygen sensor from the exhaust
pipe (Fig. 13).
(4) Remove the retaining nuts holding catalytic
converter to exhaust pipe (Fig. 14).
(5) Disconnect the exhaust pipe from the exhaust
manifold. (Fig. 15)
INSPECTION
Discard rusted clamps, broken or worn supports
and attaching parts. Replace a component with orig-
inal equipment parts, or equivalent. This will assure
proper alignment with other parts in the system and
provide acceptable exhaust noise levels.
INSTALLATION
(1) Connect the exhaust pipe to the engine exhaust
manifold. Tighten the nuts (A) to 31 N´m (23 ft. lbs.)
(Fig. 15).
Fig. 13 4.7L Catalytic Converter and O2 Sensor Configuration - 50 State Emissions
11 - 10 EXHAUST SYSTEMWJ

HEAT SHIELDS
DESCRIPTION
Heat shields are needed to protect both the vehicle
and the environment from the high temperatures
developed by the catalytic converter. The catalytic
converter releases additional heat into the exhaust
system. Under severe operating conditions, the tem-
perature increases in the area of the converter. Such
conditions can exist when the engine misfires or oth-
erwise does not operate at peak efficiency (Fig. 17).
MUFFLER
DESCRIPTION
Both the 4.0L and 4.7L engines use a stainless
steel muffler to control exhaust noise levels and
exhaust back pressure. The muffler and tailpipe are
a one piece assembly (Fig. 18).
REMOVAL
All original equipment exhaust systems are manu-
factured with the tailpipe welded to the muffler. Ser-
vice replacement mufflers and tailpipes are either
clamped together or welded together.
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.(3) Loosen the exhaust clamp on the catalytic con-
verter to muffler connection (Fig. 19).
(4) Heat the catalytic converter-to-muffler connec-
tion with a torch until the metal becomes cherry red.
(5) While the metal is still cherry red, remove the
tailpipe/muffler assembly from the catalytic con-
verter.
(6) Remove the tailpipe from the tailpipe hanger
(Fig. 20).
(7) Remove the tailpipe/muffler assembly (Fig. 20).
INSTALLATION
(1) If the tailpipe hanger assembly was removed,
install the hanger to the frame. Tighten the bolts to
22 N´m (192 in. lbs.) torque.
(2) Position the tailpipe and muffler onto the
tailpipe hanger (Fig. 20) .
(3) Install the muffler onto the catalytic converter.
Make sure that the tailpipe has sufficient clearance
from the floor pan. Install exhaust clamp and tighten
the nuts to 47 N´m (35 ft. lbs.) torque (Fig. 19) .
(4) Lower the vehicle.
(5) Start the engine and inspect for exhaust leaks
and exhaust system contact with the body panels.
Adjust the alignment, if needed.
Fig. 17 Front and Rear Floor Pan Heat Shields
Typical
1 - REAR FLOOR PAN HEAT SHIELD
2 - HEAT SHIELD RETAINING NUTS (QTY 8)
3 - FRONT FLOOR PAN HEAT SHIELD
Fig. 18 Muffler and Tailpipe
1 - CATALYTIC CONVERTER
2 - TAILPIPE HANGER
3 - TAILPIPE
4 - MUFFLER
11 - 12 EXHAUST SYSTEMWJ

FRAME & BUMPERS
TABLE OF CONTENTS
page page
FRONT ABSORBER
REMOVAL.............................1
INSTALLATION..........................1
FRONT FASCIA
REMOVAL.............................1
INSTALLATION..........................1
REAR ABSORBER
REMOVAL.............................2
INSTALLATION..........................2
REAR FASCIA
REMOVAL.............................2
INSTALLATION..........................4
FRAME
SPECIFICATIONS
SPECIFICATIONS - TORQUE.............4
FRAME DIMENSIONS...................4
FRONT SKID PLATE
REMOVAL.............................7INSTALLATION..........................7
FRONT TOW HOOK
REMOVAL.............................7
INSTALLATION..........................7
FUEL TANK SKID PLATE
DESCRIPTION..........................7
REAR TOW HOOK
REMOVAL.............................7
INSTALLATION..........................7
TRAILER HITCH
REMOVAL.............................8
INSTALLATION..........................8
TRANSFER CASE SKID PLATE
REMOVAL.............................8
INSTALLATION..........................8
FRONT ABSORBER
REMOVAL
(1) Remove front fascia, refer to (Refer to 13 -
FRAMES & BUMPERS/BUMPERS/FRONT FASCIA
- REMOVAL).
(2) Remove the retainer attaching the absorber to
the fascia.
(3) Separate the absorber from the fascia.
INSTALLATION
(1) Position the absorber on the fascia.
(2) Install the retainer attaching the absorber to
the fascia.
(3) Install front fascia. Refer to (Refer to 13 -
FRAMES & BUMPERS/BUMPERS/FRONT FASCIA
- INSTALLATION).
FRONT FASCIA
REMOVAL
(1) Raise and support vehicle.
(2) Turn front wheels to access rivets and remove
plastic rivets attaching fascia to wheel liner.
(3) Remove bolts attaching fascia to fender (Fig. 1).(4) Remove plastic push pin fasteners attaching
front fascia to lower radiator crossmember splash
shield (Fig. 2).
(5) Disengage fog lamp connectors, if equipped.
(6) Remove screws attaching fascia/grille to upper
radiator crossmember (Fig. 3).
(7) Slide fascia forward to separate from vehicle.
INSTALLATION
(1) Slide fascia onto vehicle engaging fascia with
tabs on bottom of front fenders.
(2) Install screws attaching fascia/grille to upper
radiator crossmember (Fig. 3).
(3) Install bolts attaching fascia to fender (Fig. 1).
(4) Engage fog lamp connectors, if equipped.
(5) Install plastic rivets attaching fascia to wheel
liner.
(6) Install plastic push pin fasteners attaching
front fascia to lower radiator crossmember splash
shield (Fig. 2).
(7) Remove supports and lower vehicle.
WJFRAME & BUMPERS 13 - 1

REAR ABSORBER
REMOVAL
(1) Remove rear fascia, refer to (Refer to 13 -
FRAMES & BUMPERS/BUMPERS/REAR FASCIA -
REMOVAL).
(2) Remove rivets attaching absorber to rear cross-
member (Fig. 5).
(3) Separate absorber from vehicle.
INSTALLATION
(1) Position absorber on vehicle.
(2) Install rivets attaching absorber to rear cross-
member (Fig. 2).
(3) Install rear fascia, refer to (Refer to 13 -
FRAMES & BUMPERS/BUMPERS/REAR FASCIA -
INSTALLATION).
REAR FASCIA
REMOVAL
(1) Raise and support vehicle.
(2) Remove wheels.
(3) Remove plastic push pins attaching fascia to
fuel tank skid plate.
(4) Remove plastic rivets attaching fascia to wheel
liner.
Fig. 1 Front Fascia
1 - BODY
2 - FASCIA
Fig. 2 Front Fascia
1 - WHEEL LINER
2 - FASCIA
3 - FOG LAMP CONNECTOR
4 - PLASTIC PUSH PIN
5 - PLASTIC RIVET
Fig. 3 Front Fascia
1 - SCREW
2 - FASCIA
13 - 2 FRAME & BUMPERSWJ
FRONT FASCIA (Continued)

INSTALLATION
(1) Position fascia on vehicle aligning retainers
with slots in quarter panel (Fig. 7).
(2) Press forward edges of fascia inward to engage
retainers.
(3) Install screws attaching fascia to liftgate open-
ing.
(4) Install plastic push pins attaching fascia to lift-
gate opening.
(5) Install nuts attaching upper edge of fascia to
quarter panel and wheel liner.
(6) Install plastic rivets attaching fascia to wheel
liner.
(7) Install support lower vehicle.
(8) Install plastic push pins attaching fascia to fuel
tank skid plate.
(9) Install the interior trim panels removed to
access fascia retainers.
(10) Install tie down loop screws.
(11) Install the wheels, refer to section 22 for
tightening sequence and torque specifications.
FRAME
SPECIFICATIONS
SPECIFICATIONS - TORQUE
TORQUE SPECIFICATIONS
DESCRIPTION N´mFt.
Lbs.In.
Lbs.
Front Tow Hook Bolt 54 40 Ð
Front Skid Plate Bolt 54 40 Ð
Rear Tow Hook Bolt 68 50 Ð
Trailer Hitch Bolts 68 50 Ð
Transfer Case Skid Plate
Bolts34 25 Ð
FRAME DIMENSIONS
INDEX
DESCRIPTION FIGURE
SIDE VIEW 8
BOTTOM VIEW 9
Fig. 6 Rear Fascia Retainers
1 - RETAINER
2 - FASCIA
Fig. 7 Fascia Attachment
1 - SLOT
2 - QUARTER PANEL
13 - 4 FRAME & BUMPERSWJ
REAR FASCIA (Continued)

FRONT SKID PLATE
REMOVAL
(1) Position a support under skid plate.
(2) Remove bolts attaching skid plate to frame
(Fig. 10).
(3) Separate skid plate from frame.
INSTALLATION
(1) Position skid plate on a support.
(2) Raise it into position
(3) Install bolts attaching skid plate to frame.
Tighten bolts to 54 N´m (40 ft. lbs.) torque.
FRONT TOW HOOK
REMOVAL
(1) Remove bolts that attach tow hook bracket to
the lower crossmember (Fig. 11).
(2) Separate tow hook bracket from lower cross-
member.
INSTALLATION
(1) Position tow hook bracket at the lower cross-
member.
(2) Install bolts attaching tow hook bracket to
crossmember. Tighten bolts to 54 N´m (40 ft. lbs.)
torque.
FUEL TANK SKID PLATE
DESCRIPTION
The fuel tank skid plate is integrated with the fuel
tank. Refer to Fuel Tank for service procedures
REAR TOW HOOK
REMOVAL
(1) Remove rear tow hook to frame brace.
(2) Remove bolts attaching the tow hook bracket to
frame (Fig. 12).
(3) Separate tow hook bracket from frame.
INSTALLATION
(1) position tow hook bracket on frame.
(2) Install bolts attaching tow hook bracket to
frame. Tighten bolts to 68 N´m (50 ft. lbs.) torque.
(3) Install rear tow hook to frame brace.
Fig. 10 Front Skid Plate
1 - SKID PLATE
Fig. 11 Front Tow Hook
1 - TAPPING PLATE
2 - CROSSMEMBER
3 - BRACKET
4 - TOW HOOK
Fig. 12 Rear Tow Hook
1 - TOW HOOK BRACE
2 - TOW HOOK
3 - BRACKET
4 - FUEL TANK
WJFRAME & BUMPERS 13 - 7