exj 11, JEEP Manuals, Electronic Service Manual (jeep cherokee xj do 2000)
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EXHAUST SYSTEM
11 - 1
EXHAUST SYSTEM
TABLE OF CONTENTS
page
page
DESCRIPTION AND OPERATION
DIAGNOSIS AND TESTING
REMOVAL AND INSTALLATION
SPECIFICATIONS
DESCRIPTION AND OPERATION
EXHAUST SYSTEM
DESCRIPTION
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) (Fig. 2) (Fig. 3)
Fig. 2 Exhaust Pipe—4.0L
1 – NUT
2 – EXHAUST MANIFOLD
3 – TRANSMISSION SUPPORT
4 – EXHAUST PIPE
5 – MINI CATALYTIC CONVERTER
6 – BOLT
Fig. 1 Exhaust Pipe—2.5L
1 – NUT
2 – TRANSMISSION SUPPORT
3 – MINI CATALYTIC CONVERTER
4 – EXHAUST PIPE
5 – EXHAUST MANIFOLD
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EXHAUST SYSTEM
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DESCRIPTION AND OPERATION (Continued)
Fig. 3 Exhaust System—Typical
1 – STUD
2 – TAIL PIPE HANGER
3 – CLAMP
4 – ISOLATOR
5 – BOLT
6 – TAIL PIPE HANGER
7 – NUT
8 – MUFFLER
9 – CLAMP
10 – CATALYTIC CONVERTER
11 – HEAT SHIELD
CATALYTIC CONVERTERS
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.
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-
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EXHAUST SYSTEM
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DESCRIPTION AND OPERATION (Continued)
Fig. 4 4.0L Catalytic Converter and O2 Sensor Configuration—(California Emissions only)
1 – O2 SENSOR
2 – O2 SENSOR
3 – O2 SENSOR
4 – O2 SENSOR
5 – O2 SENSOR
6 – O2 SENSOR
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. 4).
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. 5 Muffler—Typical
1 – MUFFLER
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EXHAUST SYSTEM
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DESCRIPTION AND OPERATION (Continued)
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.
Fig. 6 Tailpipe—Typical
1 – TAILPIPE
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 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.
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EXHAUST SYSTEM
11 - 5
REMOVAL AND INSTALLATION
EXHAUST PIPE
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
Rust
Penetrant (Fig. 7) (Fig. 8). Allow 5 minutes for pene-
tration.
t
Fig. 8 Exhaust Pipe Removal—4.0L
1 – NUT
2 – EXHAUST MANIFOLD
3 – TRANSMISSION SUPPORT
4 – EXHAUST PIPE
5 – MINI CATALYTIC CONVERTER
6 – BOLT
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. 7) (Fig. 8). 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. 7 Exhaust Pipe Removal—2.5L
1 – NUT
2 – TRANSMISSION SUPPORT
3 – MINI CATALYTIC CONVERTER
4 – EXHAUST PIPE
5 – EXHAUST MANIFOLD
(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
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