Jeep Grand Cherokee WK. Manual — part 1244
DIAGNOSIS AND TESTING
EXHAUST SYSTEM - GAS ENGINE
EXHAUST SYSTEM DIAGNOSIS CHART
CONDITION
POSSIBLE CAUSE
CORRECTION
EXCESSIVE EXHAUST NOISE
1. Leaks at pipe joints.
1. Tighten flanges to specified
torque at leaking joints (Refer to 11
- EXHAUST SYSTEM -
SPECIFICATIONS).
2. Burned or blown out muffler.
2. 3.7L/4.7L Replace muffler/tailpipe
assembly (Refer to 11 - EXHAUST
SYSTEM/MUFFLER - REMOVAL).
5.7L Replace muffler. Check
exhaust system.
3. Burned or rusted-out exhaust
pipe.
3. 3.7L/4.7L Replace muffler/tailpipe
assembly (Refer to 11 - EXHAUST
SYSTEM/MUFFLER - REMOVAL).
5.7L Replace tailpipe resonator
assembly (Refer to 11 - EXHAUST
SYSTEM/TAILPIPE - 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 GASES
1. Leaks at pipe joints.
1. Tighten flanges (Refer to 11 -
EXHAUST SYSTEM -
SPECIFICATIONS).
SPECIFICATIONS
TORQUE
DESCRIPTION
N·m
Ft.Lbs.
In.Lbs.
Front Exhaust to Manifold Nuts
25.7
19
-
Muffler-to-Catalytic Converter flange nuts
47
35
-
Steady rest bracket mounting bolts
47
35
-
11 - 4
EXHAUST SYSTEM
WK
CONVERTER-CATALYTIC
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 TEM-
PERATURE OF THE CONVERTER 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 front exhaust pipe/catalytic converter assembly
(3) is a hydra-form thin wall air gap design. This
design is used to reduce heat, noise and improve
emissions. When replacement is required, use original
equipment parts (or their equivalent).
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 excessive heat will not be the fault of the converter. If unburned fuel enters the con-
verter, 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 contaminating the catalyst core.
REMOVAL
3.7L ENGINE
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 lubri-
cant. Allow 5 minutes for penetration.
3. Remove transmission crossmember (Refer to 13 -
FRAME & BUMPERS/FRAME/REAR CROSSMEM-
BER - REMOVAL).
4. Disconnect and mark oxygen sensor electrical con-
nectors.
5. Remove steady rest bracket mounting bolt (5) from
transmission.
6. Remove the nuts from the front exhaust pipe/cata-
lytic converter assembly to muffler flange.
7. Remove bolts (2) and flanged nuts (1) at the
exhaust manifold.
WK
EXHAUST SYSTEM
11 - 5
8. Remove the front exhaust pipe/catalytic converter assembly (3) from the vehicle.
9. Remove steady rest bracket (4) from front exhaust pipe/catalytic converter assembly (3).
4.7L ENGINE
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 lubri-
cant. Allow 5 minutes for penetration.
3. Remove transmission crossmember (Refer to 13 -
FRAME & BUMPERS/FRAME/REAR CROSSMEM-
BER - REMOVAL).
4. Disconnect and mark oxygen sensor electrical con-
nectors.
5. Remove steady rest bracket mounting bolt (5) from
transmission.
6. Remove the nuts from the front exhaust pipe/cata-
lytic converter assembly to muffler flange.
7. Remove bolts (2) and flanged nuts (1) at the
exhaust manifold.
8. Remove the front exhaust pipe/catalytic converter assembly (3) from the vehicle.
9. Remove steady rest bracket (4) from front exhaust pipe/catalytic converter assembly (3).
5.7L ENGINE
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 lubri-
cant. Allow 5 minutes for penetration.
3. Remove transmission crossmember (Refer to 13 -
FRAME & BUMPERS/FRAME/REAR CROSSMEM-
BER - REMOVAL).
4. Disconnect and mark oxygen sensor electrical con-
nectors.
5. Remove steady rest bracket mounting bolt (5) from
transmission.
6. Remove the nuts from the front exhaust pipe/cata-
lytic converter assembly to muffler flange.
7. Remove bolts (2) and flanged nuts (1) at the
exhaust manifold.
8. Remove the front exhaust pipe/catalytic converter assembly (3) from the vehicle.
9. Remove steady rest bracket (4) from front exhaust pipe/catalytic converter assembly (3).
11 - 6
EXHAUST SYSTEM
WK
INSPECTION
Look at the stainless steel body of the converter, inspect for bulging or other distortion that could be a result of
overheating.
If you suspect internal damage to the catalyst, tapping the bottom of the catalyst with a rubber mallet may indicate
a damaged core.
INSTALLATION
3.7L ENGINE
1. Position steady rest bracket (4) onto the front
exhaust pipe/catalytic converter assembly (3).
2. Position the front exhaust pipe/catalytic converter
assembly (4) into vehicle.
3. Install the bolts (2) and nuts (1) at the front exhaust
pipe/catalytic converter assembly (3) to exhaust
manifold flange. Do not tighten.
4. Install the nuts at the front exhaust pipe/catalytic
converter assembly to muffler flange. Do not
tighten.
5. Position the exhaust pipe for proper clearance with
the frame and underbody parts. A minimum clear-
ance of 25.4 mm (1.0 in.) is required.
6. Tighten
front
exhaust
pipe/catalytic
converter
assembly to exhaust manifold bolts (2) to 25.7 N·m
(19 in. lbs.) torque.
7. Tighten the front exhaust pipe and catalytic con-
verter assembly to muffler flange nuts to 47 N·m
(35 ft. lbs.) torque.
8. Install steady rest bracket bolts. Tighten bolts to 47 N·m (35 ft. lbs.).
9. Connect oxygen sensor electrical connectors.
10. Install transmission crossmember (Refer to 13 - FRAME & BUMPERS/FRAME/REAR CROSSMEMBER -
INSTALLATION)
11. Lower vehicle.
12. Start the vehicle and inspect for exhaust leaks. Repair exhaust leaks as necessary.
WK
EXHAUST SYSTEM
11 - 7
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