The AWD gas engine exhaust system components consist of a maniverter, under floorcatalytic converter, interme-
diate pipe, muffler, clamps and support isolators

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EXHAUST SYSTEM

DIAGNOSIS AND TESTING

EXHAUST SYSTEM DIAGNOSIS

CONDITION

POSSIBLE CAUSES

CORRECTION

EXCESSIVE EXHAUST
NOISE (UNDER HOOD)

1. Exhaust manifold cracked or
broken.

1. Replace manifold.

2. Manifold to cylinder head leak.

2. Tighten manifold and/or replace gasket.

3. Exhaust flex joint to manifold leak.

3.Tighten fasteners or replace gasket.

4. Exhaust flex joint.

4. Replace catalytic converter assembly.

5. Pipe and shell noise from front
exhaust pipe.

5. Characteristic of single wall pipes.

EXCESSIVE EXHAUST
NOISE

1. Leaks at pipe joints.

1. Tighten or replace clamps at leaking
joints.

2. Burned, blown, or rusted out
exhaust pipe or muffler.

2. Replace muffler or exhaust pipes.

3. Restriction in muffler or tailpipe.

3. Remove restriction, if possible or replace
as necessary.

4. Catalytic converter material in
muffler.

4. Replace muffler and converter assembly.
Check fuel injection and ignition systems for
proper operation.

DIAGNOSIS AND TESTING - EXHAUST SYSTEM RESTRICTION CHECK

Exhaust system restriction can be checked by measuring back pressure using the DRB III

and PEP module pres-

sure tester.

WARNING: The normal operating temperature 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 converter rises to a high level after a
short period of engine operation time.

NOTE: For Special Tool identification, (Refer to 11 - EXHAUST SYSTEM - SPECIAL TOOLS).

1. Disconnect and remove the upstream (before catalytic converter) oxygen sensor. (Refer to 14 - FUEL SYSTEM/

FUEL INJECTION/O2 SENSOR - REMOVAL)

2. Install the Back Pressure Test Adaptor CH8519.

3. Connect the Pressure Transducer CH7063 to the back pressure fitting.

4. Following the PEP module instruction manual, connect all required cables to the DRB III

and PEP module.

Select the available menu options on the DRBIII

display screen for using the digital pressure gauge function.

5. Apply the park brake and start the engine.

6. With transmission in Park or Neutral, raise engine speed to 2000 RPM. Monitor the pressure readings on the

DRBIII

. Back pressure should not exceed specified limit. Refer to specification in table below EXHAUST BACK

PRESSURE LIMITS .

7. If pressure exceeds maximum limits, inspect exhaust system for restricted component. For further catalytic con-

verter inspection procedures, (Refer to 11 - EXHAUST SYSTEM/CATALYTIC CONVERTER - INSPECTION).
Replace component(s) as necessary.

EXHAUST SYSTEM

11 - 3

EXHAUST BACK PRESSURE LIMITS

Exhaust Back Pressure Limit (Max)

Vehicle in Park/Neutral (no load) @2000 RPM

3.45 Kpa (0.5 psi)

INSPECTION

Inspect the exhaust pipes, catalytic converters, muffler, and resonators for cracked joints, broken welds and corro-
sion damage that would result in a leaking exhaust system. Inspect the clamps, support brackets, and insulators for
cracks and corrosion damage.

NOTE: Slip joint band clamps are spot welded to exhaust system. If a band clamp must be replaced, the
spot weld must be ground off.

ADJUSTMENTS

EXHAUST SYSTEM ADJUSTMENTS

A misaligned exhaust system is usually indicated by a vibration, rattling noise, or binding of exhaust system com-
ponents. These noises are sometimes hard to distinguish from other chassis noises. Inspect exhaust system for
broken or loose clamps, heat shields, insulators, and brackets. Replace or tighten as necessary. It is important that
exhaust system clearances and alignment be maintained.

Perform the following procedures to align the exhaust system:

1. Loosen clamps and support brackets.

2. Align the exhaust system starting at the front, working rearward.

3. Tighten all clamps and brackets once alignment and clearances are achieved.

SPECIFICATIONS

TORQUE

DESCRIPTION

N·m

Ft. Lbs.

In. Lbs.

Fastener, Band Clamps

Fasteners, Catalytic Converter to Exhaust Manifold Flange

250

Fastener, under floor catalytic converter to maniverter - AWD

Fasteners, Intermediate Pipe Heat Shield

3.7

Fasteners, Support Brackets (Frame Rail Mounted)

8.5

Fasteners, Support Bracket (Rear Panel Mounted)

3.7

Fasteners, Charge Air Cooler

Hose Clamps, Charge Air Cooler

1.7

Banjo Fitting, Coolant Line

Brass Fitting, Coolant/Oil Line

Flared Fitting, Coolant/Oil Line

Elbow

250

Elbow Support Bracket

M8 Fasteners

250

M10 Fasteners

Fasteners, Exhaust Manifold/Turbocharger Assembly to Cylinder
Head

250

Fasteners, Heat Shield

250

Fasteners, Oil Return Tube

105

Turbocharger Support Bracket

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EXHAUST SYSTEM

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