catalytic converter JEEP GRAND CHEROKEE 2003 WJ / 2.G Workshop Manual

Carefully remove radiator pressure cap from filler
neck and check coolant level. Push down on cap to
disengage it from stop tabs. Wipe inside of filler neck
and examine lower inside sealing seat for nicks,
cracks, paint, dirt and solder residue. Inspect radia-
tor-to- reserve/overflow tank hose for internal
obstructions. Insert a wire through the hose to be
sure it is not obstructed.
Inspect cams on outside of filler neck. If cams are
damaged, seating of pressure cap valve and tester
seal will be affected.
Attach pressure tester (7700 or an equivalent) to
radiator filler neck (Fig. 6).
Operate tester pump to apply 103.4 kPa (15 psi)
pressure to system. If hoses enlarge excessively or
bulges while testing, replace as necessary. Observe
gauge pointer and determine condition of cooling sys-
tem according to following criteria:
Holds Steady:If pointer remains steady for two
minutes, serious coolant leaks are not present in sys-
tem. However, there could be an internal leak that
does not appear with normal system test pressure. If
it is certain that coolant is being lost and leaks can-
not be detected, inspect for interior leakage or per-
form Internal Leakage Test.
Drops Slowly:Indicates a small leak or seepage
is occurring. Examine all connections for seepage or
slight leakage with a flashlight. Inspect radiator,
hoses, gasket edges and heater. Seal small leak holes
with a Sealer Lubricant (or equivalent). Repair leak
holes and inspect system again with pressure
applied.
Drops Quickly:Indicates that serious leakage is
occurring. Examine system for external leakage. If
leaks are not visible, inspect for internal leakage.
Large radiator leak holes should be repaired by a
reputable radiator repair shop.INTERNAL LEAKAGE INSPECTION
Remove engine oil pan drain plug and drain a
small amount of engine oil. If coolant is present in
the pan, it will drain first because it is heavier than
oil. An alternative method is to operate engine for a
short period to churn the oil. After this is done,
remove engine dipstick and inspect for water glob-
ules. Also inspect transmission dipstick for water
globules and transmission fluid cooler for leakage.
WARNING: WITH RADIATOR PRESSURE TESTER
TOOL INSTALLED ON RADIATOR, DO NOT ALLOW
PRESSURE TO EXCEED 110 KPA (20 PSI). PRES-
SURE WILL BUILD UP QUICKLY IF A COMBUSTION
LEAK IS PRESENT. TO RELEASE PRESSURE,
ROCK TESTER FROM SIDE TO SIDE. WHEN
REMOVING TESTER, DO NOT TURN TESTER MORE
THAN 1/2 TURN IF SYSTEM IS UNDER PRESSURE.
Operate engine without pressure cap on radiator
until thermostat opens. Attach a Pressure Tester to
filler neck. If pressure builds up quickly it indicates a
combustion leak exists. This is usually the result of a
cylinder head gasket leak or crack in engine. Repair
as necessary.
If there is not an immediate pressure increase,
pump the Pressure Tester. Do this until indicated
pressure is within system range of 110 kPa (16 psi).
Fluctuation of gauge pointer indicates compression or
combustion leakage into cooling system.
Because the vehicle is equipped with a catalytic
converter,do notremove spark plug cables or short
out cylinders to isolate compression leak.
If the needle on dial of pressure tester does not
fluctuate, race engine a few times to check for an
abnormal amount of coolant or steam. This would be
emitting from exhaust pipe. Coolant or steam from
exhaust pipe may indicate a faulty cylinder head gas-
ket, cracked engine cylinder block or cylinder head.
A convenient check for exhaust gas leakage into
cooling system is provided by a commercially avail-
able Block Leak Check tool. Follow manufacturers
instructions when using this product.
COMBUSTION LEAKAGE TEST - WITHOUT
PRESSURE TESTER
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
Drain sufficient coolant to allow thermostat
removal. (Refer to 7 - COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT - REMOVAL). Remove
Fig. 6 Pressure Testing Cooling SystemÐTypical
1 - TYPICAL COOLING SYSTEM PRESSURE TESTER
WJCOOLING 7 - 11
COOLING (Continued)

All Jeep engines are equipped with a high quality
full-flow, throw-away type oil filter. DaimlerChrysler
Corporation recommends a Mopartor equivalent oil
filter be used.
(1) Position a drain pan under the oil filter.
(2) Using a suitable oil filter wrench loosen filter.
(3) Rotate the oil filter counterclockwise to remove
it from the cylinder block oil filter boss or filter
adapter housing (Fig. 75).
(4) When filter separates from adapter nipple, tip
gasket end upward to minimize oil spill. Remove fil-
ter from vehicle.
(5) Make sure old gasket comes off with oil filter.
With a wiping cloth, clean the gasket sealing surface
(Fig. 76) of oil and grime.
INSTALLATION
(1) Lightly lubricate oil filter gasket with engine
oil or chassis grease.
(2) Thread filter onto adapter nipple. When gasket
makes contact with sealing surface, (Fig. 76) hand
tighten filter one full turn, do not over tighten.
(3) Add oil, verify crankcase oil level and start
engine. Inspect for oil leaks.
OIL PAN
DESCRIPTION
The oil pan is made of stamped steel. The oil pan
gasket is a one piece steel backbone silicone coated
gasket (Fig. 77).
REMOVAL
(1) Disconnect negative cable from battery.
(2) Raise the vehicle.
(3) Remove the oil pan drain plug and drain the
engine oil.
(4) Disconnect the exhaust pipe at the exhaust
manifold.
(5) Disconnect the exhaust hanger at the catalytic
converter and lower the pipe.
(6) Remove the starter motor. (Refer to 8 - ELEC-
TRICAL/STARTING/STARTER MOTOR - REMOV-
AL).
(7) Remove the engine flywheel and transmission
torque converter housing access cover.
(8) If equipped with an oil level sensor, disconnect
the sensor.
(9) Position a jack stand directly under the engine
vibration damper.
Fig. 75 Oil FilterÐ4.0L Engine
1 - CYLINDER BLOCK
2 - ADAPTER
3 - OIL FILTER
Fig. 76 Oil Filter Sealing SurfaceÐTypical
1 - SEALING SURFACE
2 - RUBBER GASKET
3 - OIL FILTER
Fig. 77 Oil Pan
1 - OIL PAN
2 - OIL PAN DRAIN PLUG
9 - 54 ENGINE - 4.0LWJ
OIL FILTER (Continued)

EXHAUST SYSTEM
TABLE OF CONTENTS
page page
EXHAUST SYSTEM
DESCRIPTION - EXHAUST SYSTEM.........1
DIAGNOSIS AND TESTING - EXHAUST
SYSTEM.............................3
SPECIFICATIONS
TORQUE.............................3
CATALYTIC CONVERTER - 4.0L
DESCRIPTION - CATALYTIC CONVERTER
4.0L ENGINE..........................4
REMOVAL.............................4
INSPECTION...........................5
INSTALLATION..........................5
CATALYTIC CONVERTER - 4.7L
DESCRIPTION - CATALYTIC CONVERTER.....6
REMOVAL.............................6
INSPECTION...........................7
INSTALLATION..........................7EXHAUST PIPE - 4.0L
REMOVAL.............................8
INSPECTION...........................8
INSTALLATION..........................8
EXHAUST PIPE - 4.7L
REMOVAL.............................10
INSPECTION..........................10
INSTALLATION.........................10
HEAT SHIELDS
DESCRIPTION.........................12
MUFFLER
DESCRIPTION.........................12
REMOVAL.............................12
INSTALLATION.........................12
TAILPIPE
DESCRIPTION.........................13
OPERATION...........................13
EXHAUST SYSTEM
DESCRIPTION - EXHAUST SYSTEM
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: Avoid application of rust prevention com-
pounds or undercoating materials to exhaust sys-
tem floor pan heat shields. Light overspray near the
edges is permitted. Application of coating will result
in excessive floor pan temperatures and objection-
able fumes.
The exhaust system uses a single muffler with a
welded tailpipe.The 50 State Emissions vehicles use two mini cat-
alytic converters inline with the exhaust pipe below
the exhaust manifolds.
The exhaust manifolds are equipped with ball
flange outlets to assure a tight seal and strain free
connections.
The exhaust system must be properly aligned to
prevent stress, leakage and body contact. If the sys-
tem contacts any body panel, it may amplify objec-
tionable noises originating from the engine or body.
When inspecting an exhaust system, critically
inspect for cracked or loose joints, stripped screw or
bolt threads, corrosion damage and worn, cracked or
broken hangers. Replace all components that are
badly corroded or damaged. DO NOT attempt to
repair.
When replacement is required, use original equip-
ment parts (or their equivalent). This will assure
proper alignment and provide acceptable exhaust
noise levels.
The basic exhaust system consists of exhaust man-
ifold(s), exhaust pipe with oxygen sensors, catalytic
converter(s), heat shield(s), muffler and tailpipe (Fig.
1) and (Fig. 2).
WJEXHAUST SYSTEM 11 - 1

Fig. 1 Exhaust SystemÐ4.0L
1 - MINI CONVERTERS (2)
2 - CATALYTIC CONVERTER TO EXHAUST PIPE FLANGE JOINT
3 - CATALYTIC CONVERTER
4 - MUFFLER5 - TAILPIPE
6 - TAILPIPE HANGER REAR MOUNT INSULATOR
7 - EXHAUST PIPE HANGER AND MOUNT INSULATOR
Fig. 2 Exhaust SystemÐ4.7L
1 - EXHAUST PIPE WITH CATALYTIC CONVERTERS
2 - EXHAUST PIPE TO CATALYTIC CONVERTER FLANGE JOINT
3 - CATALYTIC CONVERTER
4 - MUFFLER5 - TAILPIPE
6 - TAILPIPE HANGER REAR MOUNT INSULATOR
7 - EXHAUST PIPE HANGER AND MOUNT INSULATOR
11 - 2 EXHAUST SYSTEMWJ
EXHAUST SYSTEM (Continued)

DIAGNOSIS AND TESTING - EXHAUST SYSTEM
EXHAUST SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSE CORRECTION
EXCESSIVE EXHAUST NOISE1. Leaks at pipe joints. 1. Tighten clamps to specified
torque at leaking joints (Refer to 11
- EXHAUST SYSTEM -
SPECIFICATIONS).
2. Burned or blown out muffler. 2. Replace muffler assembly (Refer
to 11 - EXHAUST SYSTEM/
MUFFLER - REMOVAL). Check
exhaust system.
3. Burned or rusted-out exhaust
pipe.3. Replace exhaust pipe (Refer to
11 - EXHAUST SYSTEM/EXHAUST
PIPE - REMOVAL).
4. Exhaust pipe leaking at manifold
flange.4. Tighten connection attaching nuts
(Refer to 11 - EXHAUST SYSTEM -
SPECIFICATIONS).
5. Exhaust manifold cracked or
broken.5. Replace exhaust manifold (Refer
to 9 - ENGINE/MANIFOLDS/
EXHAUST MANIFOLD -
REMOVAL).
6. Leak between exhaust manifold
and cylinder head.6. Tighten exhaust manifold to
cylinder head stud nuts or bolts
(Refer to 9 - ENGINE -
SPECIFICATIONS).
7. Restriction in muffler or tailpipe. 7. Remove restriction, if possible.
Replace muffler or tailpipe, as
necessary.
8. Exhaust system contacting body
or chassis.8. Re-align exhaust system to clear
surrounding components.
LEAKING EXHAUST GASES1. Leaks at pipe joints. 1. Tighten/replace clamps at leaking
joints (Refer to 11 - EXHAUST
SYSTEM - SPECIFICATIONS).
SPECIFICATIONS
TORQUE
DESCRIPTION N´m Ft. In.
Lbs. Lbs.
Catalytic Converter-to-
Exhaust PipeÐNuts28 Ð 250
Exhaust Pipe-to-ManifoldÐ
Nuts31 23 Ð
Heat Shield RetainingÐ
Nuts2.0 Ð 20DESCRIPTION N´m Ft. In.
Lbs. Lbs.
Muffler-to-Catalytic
Converter
U-bolt clamp 47 35 Ð
Rear Tailpipe HangerÐ
Bolts22 Ð 192
WJEXHAUST SYSTEM 11 - 3
EXHAUST SYSTEM (Continued)

CATALYTIC CONVERTER - 4.0L
DESCRIPTION - CATALYTIC CONVERTER 4.0L
ENGINE
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. 3).
REMOVAL
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
Fig. 3 4.0L Catalytic Converter and O2 Sensor Configuration - 50 State Emissions
11 - 4 EXHAUST SYSTEMWJ

(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.
(3) Remove nuts from the catalytic converter and
exhaust pipe flange connection (Fig. 4).
(4) Loosen exhaust clamp from the catalytic con-
verter and muffler connection (Fig. 4).
(5) Disconnect oxygen sensor wiring (Fig. 4).
(6) Heat the catalytic converter to muffler connec-
tion with a torch until the metal becomes cherry red.
(7) While the metal is still cherry red, twist the
catalytic converter back and forth to separate it from
the exhaust pipe and the muffler (Fig. 5).
INSPECTION
Look at the stainless steel body of the converter,
inspect for bulging or other distortion that could be a
result of overheating. If the converter has a heat
shield attached make sure it is not bent or loose.If you suspect internal damage to the catalyst, tap-
ping the bottom of the catalyst with a rubber mallet
may indicate a damaged core.
INSTALLATION
(1) Position the catalytic converter onto the
exhaust pipe flange connection (Fig. 4). Tighten the
nuts to 28 N´m (250 in. lbs.) torque.
(2) Install the muffler onto the catalytic converter
until the alignment tab is inserted into the align-
ment slot.
(3) Install the exhaust clamp at the muffler and
catalytic converter connection (Fig. 4). Tighten the
clamp nuts to 47 N´m (35 ft. lbs.) torque.
(4) Connect oxygen sensor wiring (Fig. 4).
(5) Lower the vehicle.
(6) Start the engine and inspect for exhaust leaks
and exhaust system contact with the body panels.
Adjust the alignment, if needed.
Fig. 4 Exhaust Pipe-to-Catalytic Converter-to-Muffler
Connection
1 - EXHAUST CLAMP ASSEMBLY
2 - OXYGEN SENSOR
3 - MUFFLER
4 - CATALYTIC CONVERTER
5 - EXHAUST PIPE WITH FLANGE JOINT
6 - NUTS (3)
Fig. 5 Catalytic ConverterÐRemoval
1 - EXHAUST PIPE WITH FLANGE
2 - NUTS (3)
3 - CATALYTIC CONVERTER
WJEXHAUST SYSTEM 11 - 5
CATALYTIC CONVERTER - 4.0L (Continued)

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

(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.
(3) Remove nuts from the catalytic converter and
exhaust pipe flange connection (Fig. 7).
(4) Loosen exhaust clamp from the catalytic con-
verter and muffler connection (Fig. 7).
(5) Disconnect oxygen sensor wiring (Fig. 7).
(6) Heat the catalytic converter to muffler connec-
tion with a torch until the metal becomes cherry red.
(7) While the metal is still cherry red, twist the
catalytic converter back and forth to separate it from
the muffler (Fig. 8).
INSPECTION
Look at the stainless steel body of the converter,
inspect for bulging or other distortion that could be a
result of overheating. If the converter has a heat
shield attached make sure it is not bent or loose.
If you suspect internal damage to the catalyst, tap-
ping the bottom of the catalyst with a rubber mallet
may indicate a damaged core.
INSTALLATION
(1) Position the catalytic converter onto the
exhaust pipe flange connection (Fig. 7). Tighten the
nuts to 28 N´m (250 in. lbs.) torque.
(2) Install the muffler onto the catalytic converter
until the alignment tab is inserted into the align-
ment slot.
(3) Install the exhaust clamp at the muffler and
catalytic converter connection (Fig. 7). Tighten the
clamp nuts to 47 N´m (35 ft. lbs.) torque.
(4) Connect oxygen sensor wiring (Fig. 7).
(5) Lower the vehicle.
(6) Start the engine and inspect for exhaust leaks
and exhaust system contact with the body panels.
Adjust the alignment, if needed.
Fig. 7 Exhaust Pipe-to-Catalytic Converter-to-Muffler
Connection
1 - EXHAUST CLAMP ASSEMBLY
2 - OXYGEN SENSOR
3 - MUFFLER
4 - CATALYTIC CONVERTER
5 - EXHAUST PIPE WITH FLANGE JOINT
6 - NUTS (3)
Fig. 8 Catalytic ConverterÐRemoval
1 - EXHAUST PIPE WITH FLANGE
2 - NUTS (3)
3 - CATALYTIC CONVERTER
WJEXHAUST SYSTEM 11 - 7
CATALYTIC CONVERTER - 4.7L (Continued)

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