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EXHAUST SYSTEM AND INTAKE MANIFOLD
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EXHAUST SYSTEM AND INTAKE MANIFOLD
CONTENTS
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page
EXHAUST SYSTEM .......................
EXHAUST SYSTEM DIAGNOSIS .............
SERVICE PROCEDURES ...................
TORQUE SPECIFICATIONS ................
EXHAUST SYSTEM
GENERAL INFORMATION
The basic exhaust system consists of exhaust mani-
fold(s), exhaust pipe with oxygen sensor, catalytic con-
verter, heat shield(s), muffler and tailpipe (Fig. 1 or
2).
Fig. 2 Exhaust System (5.2L Engine)
Fig. 1 Exhaust System (4.0L Engine)
When inspecting an exhaust system, critically in-
spect for cracked or loose joints, stripped screw or bolt
threads, corrosion damage and worn, cracked or bro-
ken 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 exhaust system uses a single muffler with a
single monolithic-type catalytic converter.
The 4.0L engines use a seal between the exhaust
manifold and exhaust pipe to assure a tight seal and
strain free connections.
The 5.2L 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.
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.
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CATALYTIC CONVERTER
The stainless steel catalytic converter body is de-
signed 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 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 contami-
nating the catalyst core.
HEAT SHIELDS
Heat shields are needed to protect both the vehicle
and the environment from the high temperatures de-
veloped by the catalytic converter (Fig. 3 or 4). The
catalytic converter releases additional heat into the
exhaust system. Under severe operating conditions,
the temperature increases in the area of the con-
verter. Such conditions can exist when the engine
misfires or otherwise does not operate at peak effi-
ciency.
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.
DO NOT allow the engine to operate at fast idle for
extended periods (over 5 minutes). This condition
may result in excessive temperatures in the exhaust
system and on the floor pan.
Fig. 3 Front Floor Pan Heat Shield
EXHAUST GAS RECIRCULATION (EGR)
To assist in the control of oxides of nitrogen (NOx)
in engine exhaust, all engines are equipped with an
exhaust gas recirculation system. The use of exhaust
gas to dilute incoming air/fuel mixtures lowers peak
flame temperatures during combustion, thus limiting
the formation of NOx.
Exhaust gases are piped from the exhaust manifold
to the intake manifold through an EGR tube. Refer to
Group 25, Emission Control Systems for complete
description, diagnosis and service procedures of the
exhaust gas recirculation system and components.
Fig. 4 Rear Floor Pan Heat Shield
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EXHAUST SYSTEM AND INTAKE MANIFOLD
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EXHAUST SYSTEM DIAGNOSIS
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SERVICE PROCEDURES
INDEX
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Catalytic Converter .......................
Exhaust Manifold—4.0L Engine ...............
Exhaust Manifold—5.2L Engine ...............
Exhaust Pipe ............................
Intake Manifold—4.0L Engine .................
Intake Manifold—5.2L Engine .................
Muffler and Tailpipe .......................
EXHAUST PIPE
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
REMOVAL
(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. 1 or 2).
Fig. 2 Exhaust Pipe (5.2L Engine)
(b) While the metal is still cherry red, twist the
exhaust pipe back and forth to separate it from the
catalytic converter.
(6) Disconnect the exhaust pipe hanger from the
rear mount bracket insulator (Fig. 3).
(7) Remove the exhaust pipe.
Fig. 1 Exhaust Pipe (4.0L Engine)
INSTALLATION
(1) Position the exhaust pipe onto the catalytic con-
verter.
(2) Connect the exhaust pipe hanger to the rear
mount bracket insulator.
(3) On 4.0L engines, install a new seal between the
exhaust pipe and the engine exhaust manifold (Fig.
1). Connect the exhaust pipe to the engine exhaust
manifold. Tighten the nuts to 31 N
(4) Disconnect the exhaust pipe from the engine
exhaust manifold. On 4.0L engines, discard the ex-
haust manifold seal (Fig. 1).
(5) Remove the exhaust clamp and nuts from the
exhaust pipe and catalytic converter connection (Fig.
1 or 2). Disconnect the exhaust pipe from the catalytic
converter. If needed:
(a) Heat the exhaust pipe and catalytic converter
connection with an torch until the metal becomes
cherry red.
I
m (23 ft. lbs.)
torque.
(4) Position the exhaust clamp assembly over the
exhaust pipe/catalytic converter connection (Fig. 1 or
2). Tighten the nuts to 34 N
I
I
m (35 ft. lbs.) torque.
m (25 ft. lbs.) torque.
(5) Coat the oxygen sensor with anti-seize com-
pound. Install the sensor and tighten the nut to 48
N
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EXHAUST SYSTEM AND INTAKE MANIFOLD
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Fig. 3 Rear Mount Bracket Insulator
(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.
(8) After initial start-up, check the engine exhaust
manifold to exhaust pipe nuts for proper torque.
Fig. 4 Exhaust Pipe-to-Catalytic Converter-to-Muffler
Connection
(3) Install the exhaust clamp assembly at the muf-
fler and catalytic converter connection (Fig. 4).
Tighten the clamp nuts to 34 N
CATALYTIC CONVERTER
(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.
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
MUFFLER AND TAILPIPE
All original equipment exhaust systems are manu-
factured with the tailpipe welded to a stamped muf-
fler. Service replacement mufflers and tailpipes are
either clamped together or welded together.
REMOVAL
(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.
(3) Remove the clamp and nuts from the catalytic
converter and exhaust pipe connection (Fig. 4).
(4) Remove the clamp and nuts from the catalytic
converter and muffler connection (Fig. 4).
(5) Heat the exhaust pipe, catalytic converter and
muffler connections with an torch until the metal
becomes cherry red.
(6) While the metal is still cherry red, twist the
catalytic converter back and forth to separate it from
the exhaust pipe and the muffler.
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
REMOVAL
(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.
(3) Remove the exhaust clamp and nuts from the
catalytic converter and muffler connection (Fig. 4).
(4) Heat the catalytic converter-to-muffler connec-
tion with an torch until the metal becomes cherry red.
(5) While the metal is still cherry red, remove the
tail pipe/muffler assembly from the catalytic con-
verter.
(6) Remove the tailpipe from the tailpipe hanger
(Fig. 5).
(7) Remove the tailpipe/muffler assembly.
INSTALLATION
(1) Position the exhaust clamp assembly over the
exhaust pipe/catalytic converter connection (Fig. 4).
Tighten the nuts to 34 N
I
I
m (25 ft. lbs.) torque.
m (25 ft. lbs.) torque.
(2) Install the muffler onto the catalytic converter
until the alignment tab is inserted into the alignment
slot.
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