Jeep XJ. Manual — part 327
CATALYTIC CONVERTERS
DESCRIPTION
California emissions vehicles incorporate two mini
catalytic converters into the exhaust system. These
catalytic converters are made of stainless steel
designed to operate at extremely high temperatures.
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.
Federal emission vehicles use only one catalytic
converter,
However,
California
emission
vehicles
incorporate two mini catalytic converters located
after the exhaust manifolds and before the inline cat-
alytic converter (Fig. 7).
MUFFLER
DESCRIPTION
Both the 2.5L and 4.0L engines use a galvanized
steel muffler to control exhaust noise levels and
exhaust back pressure.
Fig. 7 4.0L Catalytic Converter and O2 Sensor Configuration—California and Federal Emissions
1 – O2 SENSOR
2 – O2 SENSOR
3 – O2 SENSOR
4 – O2 SENSOR
5 – O2 SENSOR
6 – O2 SENSOR
11 - 4
EXHAUST SYSTEM
XJ
DESCRIPTION AND OPERATION (Continued)
2000 XJ Service Manual
Publication No. 81-370-0046
TSB 26-03-00
March, 2000
TAILPIPE
DESCRIPTION
The tail pipe is also made of galvanized steel
OPERATION
The tailpipe channels the exhaust out of the muf-
fler and out from under the vehicle to control noise
and prevent exhaust gas fumes from entering the
passenger compartment.
DIAGNOSIS AND TESTING
EXHAUST SYSTEM
EXHAUST SYSTEM DIAGNOSIS CHART
CONDITION
POSSIBLE CAUSE
CORRECTION
EXCESSIVE EXHAUST NOISE
OR LEAKING EXHAUST GASES
1. Leaks at pipe joints.
1. Tighten clamps/bolts to specified
torque at leaking joints.
2. Rusted or blown out muffler.
2. Replace muffler. Inspect exhaust
system.
3. Broken or rusted out exhaust pipe.
3. Replace exhaust pipe.
4. Exhaust pipe leaking at manifold
flange.
4. Tighten/replace flange attaching
nuts/bolts.
5. Exhaust manifold cracked or
broken.
5. Replace exhaust manifold.
6. Leak between exhaust manifold
and cylinder head.
6. Tighten exhaust manifold to
cylinder head bolts.
7. Catalytic converter rusted or
blown out.
7. Replace catalytic converter assy.
8. Restriction in exhaust system.
8. Remove restriction, if possible.
Replace restricted part if necessary.
When servicing and replacing exhaust system components, disconnect the oxygen sensor connector(s). Allowing
the exhaust to hang by the oxygen sensor wires will damage the harness and/or sensor.
Fig. 8 Muffler—Typical
1 – MUFFLER
Fig. 9 Tailpipe—Typical
1 – TAILPIPE
XJ
EXHAUST SYSTEM
11 - 5
DESCRIPTION AND OPERATION (Continued)
2000 XJ Service Manual
Publication No. 81-370-0046
TSB 26-03-00
March, 2000
REMOVAL AND INSTALLATION
EXHAUST PIPE—EARLY BUILD
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
CAUTION: When servicing exhaust system compo-
nents, disconnect the oxygen sensor connector.
Allowing the exhaust system to hang by the oxygen
sensor harness will damage the wiring and/or sen-
sor.
REMOVAL
(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with Mopar
t Rust
Penetrant (Fig. 10) (Fig. 11). Allow 5 minutes for
penetration.
(3) Disconnect the oxygen sensor connector(s).
(4) Disconnect the exhaust pipe from the engine
exhaust manifold. Discard the seal (4.0L engine,
only).
(5) Support the transmission and remove the rear
crossmember.
(6) Remove the clamp nuts and clamp. To remove
the exhaust pipe from the catalytic converter, apply
heat until the metal becomes cherry red. Disconnect
the
exhaust
pipe
from
the
catalytic
converter.
Remove the exhaust pipe.
INSTALLATION
(1) Assemble exhaust pipe to manifold and cata-
lytic converter loosely to permit proper alignment of
all parts.
(2) Use a new clamp and tighten the nuts to 61
N·m (45 ft. lbs.) torque.
(3) Connect the exhaust pipe to the engine exhaust
manifold (Fig. 10) (Fig. 11). Install a new seal
between the exhaust manifold and the exhaust pipe
(4.0L engine only). Tighten the nuts to 31 N·m (23 ft.
lbs.) torque.
(4) Install
the
rear
crossmember.
Install
and
tighten the four (4) crossmember to rear mount nuts
to 22 N·m (16 ft. lbs.) Install and tighten the cross-
member to sill bolts to 42 N·m (31 ft. lbs.) torque.
Remove the support from the transmission.
(5) Carefully coat the threads on the oxygen sen-
sor(s) with anti-seize compound. Install the sensor
and tighten the nut to 27 N·m (20 ft. lbs.) torque.
(6) Lower the vehicle.
(7) Start the engine and inspect for exhaust leaks
and exhaust system contact with the body panels.
Adjust the alignment, if needed.
Fig. 10 Exhaust Pipe Removal—2.5L Early Build
1 – NUT
2 – TRANSMISSION SUPPORT
3 – MINI CATALYTIC CONVERTER
4 – EXHAUST PIPE
5 – EXHAUST MANIFOLD
Fig. 11 Exhaust Pipe Removal—4.0L Early Build
1 – NUT
2 – EXHAUST MANIFOLD
3 – TRANSMISSION SUPPORT
4 – EXHAUST PIPE
5 – MINI CATALYTIC CONVERTER
6 – BOLT
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EXHAUST SYSTEM
XJ
2000 XJ Service Manual
Publication No. 81-370-0046
TSB 26-03-00
March, 2000
EXHAUST PIPE—LATE BUILD
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
CAUTION: When servicing exhaust system compo-
nents, disconnect the oxygen sensor connector.
Allowing the exhaust system to hang by the oxygen
sensor harness will damage the wiring and/or sen-
sor.
REMOVAL
(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with Mopar
t Rust
Penetrant. Allow 5 minutes for penetration.
(3) Disconnect the oxygen sensor connector(s).
(4) Disconnect the exhaust pipe from the engine
exhaust manifold (Fig. 12) (Fig. 13).
(5) Disconnect the exhaust flange at the exhaust
pipe to catalytic converter
(6) Slide the exhaust pipe toward rear of vehicle to
disengage exhaust hanger from transmission support.
Remove exhaust pipe.
INSTALLATION
(1) Position exhaust pipe into vehicle.
(2) Position exhaust hanger into transmission sup-
port.
(3) Position exhaust pipe onto exhaust manifold
(Fig. 12) (Fig. 13). Install mounting nuts and bolts.
DO NOT tighten nuts and bolts at this time.
(4) Position catalytic converter flange onto exhaust
pipe flange. Install three nuts and tighten to 28.5
N·m (21 ft. lbs.).
(5) Tighten exhaust pipe to exhaust manifold
mounting bolts and nuts to 31 N·m (23 ft. lbs.).
(6) Connect the oxygen sensor connector(s).
(7) Lower vehicle.
(8) Start engine check for leaks.
CATALYTIC CONVERTER—EARLY BUILD
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
Fig. 12 Exhaust Pipe Removal—2.5L Late Build
1 – EXHAUST MANIFOLD
2 – TRANSMISSION SUPPORT
3 – EXHAUST FLANGE JOINT
4 – EXHAUST PIPE
5 – MINI CATALYTIC CONVERTER
6 – NUT
Fig. 13 Exhaust Pipe Removal—4.0L Late Build
1 – NUT
2 – EXHAUST MANIFOLD
3 – EXHAUST FLANGE JOINT
4 – TRANSMISSION SUPPORT
5 – EXHAUST FLANGE JOINT
6 – EXHAUST PIPE
7 – MINI CATALYTIC CONVERTER
XJ
EXHAUST SYSTEM
11 - 7
REMOVAL AND INSTALLATION (Continued)
2000 XJ Service Manual
Publication No. 81-370-0046
TSB 26-03-00
March, 2000
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