Exhaust Manifold Pipe Replacement 7.8L and 7.2L CAT

Removal Procedure

1. Remove the clamp from the turbocharger/exhaust brake.
2. Remove the clamp from the exhaust pipe bracket.



3. Remove the band clamp from the flex pipe.
4. Remove the front exhaust pipe.
5. Inspect all of the components for the following conditions:

•

Cracks

•

Bends

•	Stripped threads

•	Corrosion damage

•

Leaks

6. Replace the above components as necessary.

Installation Procedure

1. Install the front exhaust pipe.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

2. Install the band clamp to flex pipe.

Tighten
Tighten the clamp to 24 N·m (18 lb ft).




3. Install the clamps on the front exhaust pipe.

Tighten

1. Tighten the turbocharger/exhaust brake clamp assembly to 10 N·m (89 lb in).
2. Tighten the exhaust pipe bracket clamp nut to 24 N·m (18 lb ft).

Exhaust Manifold Pipe Replacement L18

Removal Procedure

Caution: In order to avoid being burned, do not service the exhaust system while it is still hot. Service the system when it is cool.

Caution: Always wear protective goggles and gloves when removing exhaust parts as falling rust and sharp edges from worn exhaust components could result in serious personal injury.

1. Remove the exhaust muffler. Refer to Muffler Replacement .
2. Remove the clip around the engine harness and the oxygen sensors pigtail.
3. Disconnect the connector position assurance (CPA) retainers.
4. Disconnect the oxygen sensors electrical connector.
5. If replacing the exhaust manifold pipe, remove the oxygen sensors.



6. Remove the exhaust manifold pipe nuts.



7. Remove the exhaust manifold pipe.
8. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.
9. Discard the exhaust manifold pipe seal.

Installation Procedure

Notice: When inspecting or replacing exhaust system components, make sure there is adequate clearance from all points on the underbody to prevent overheating of the floor pan and possible damage to the passenger compartment insulation and trim materials.

1. Install a new exhaust manifold pipe seal to the exhaust manifold pipe.
2. Install the exhaust manifold pipe.
3. Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
4. Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.

Notice: Refer to Fastener Notice in the Preface section.




5. Install the exhaust manifold pipe nuts.

Tighten
Tighten the nuts to 50 N·m (39 lb ft).




6. If the exhaust manifold pipe was replaced perform the following:

6.1.	Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensor.

6.2.	Install the old oxygen sensor.

Tighten
Tighten the sensor to 42 N·m (31 lb ft).

7. If the exhaust manifold pipe was not replaced perform the following:

7.1.	Connect the oxygen sensor electrical connector.

7.2.	Connect the CPA retainer.

7.3.	Install the clip around the engine harness and the oxygen sensor pigtail.

8. Install the exhaust muffler. Refer to Muffler Replacement .

Exhaust Manifold Pipe Replacement LLY

Removal Procedure

Caution: In order to avoid being burned, do not service the exhaust system while it is still hot. Service the system when it is cool.

Caution: Always wear protective goggles and gloves when removing exhaust parts as falling rust and sharp edges from worn exhaust components could result in serious personal injury.

1. Remove the engine cover. Refer to Engine Cover Replacement .
2. Loosen the exhaust manifold pipe clamp.
3. Slide the exhaust manifold pipe clamp down onto the exhaust manifold pipe.
4. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .



5. Remove the catalytic converter to exhaust manifold pipe nuts.



6. Remove the exhaust manifold pipe hanger bracket nuts (2).
7. Remove the exhaust manifold pipe and hanger bracket from the vehicle.
8. Remove the exhaust manifold pipe hanger bracket from the manifold pipe.
9. Remove and discard the exhaust manifold pipe to catalytic converter gasket.

Installation Procedure

Notice: When inspecting or replacing exhaust system components, make sure there is adequate clearance from all points on the underbody to prevent overheating of the floor pan and possible damage to the passenger compartment insulation and trim materials.

1. Install a NEW gasket onto the exhaust manifold pipe studs.
2. Install the exhaust manifold pipe hanger bracket to the manifold pipe.
3. Position and install the exhaust manifold pipe and hanger bracket to the vehicle.

Notice: Refer to Fastener Notice in the Preface section.

4. Install the exhaust manifold pipe hanger bracket nuts (2).

Tighten
Tighten the nuts to 85 N·m (63 lb ft).




5. Install the catalytic converter to exhaust manifold pipe nuts.

Tighten
Tighten the nuts to 45 N·m (33 lb ft).

6. Lower the vehicle.



7. Slide the exhaust manifold pipe clamp up into position.
8. Tighten the exhaust manifold pipe clamp.

Tighten
Tighten the clamp to 12.5 N·m (106 lb in).

9. Install the engine cover. Refer to Engine Cover Replacement .

Exhaust Manifold Pipe Replacement LMM

Removal Procedure

Caution: In order to avoid being burned, do not service the exhaust system while it is still hot. Service the system when it is cool.

Caution: Always wear protective goggles and gloves when removing exhaust parts as falling rust and sharp edges from worn exhaust components could result in serious personal injury.

1. Remove the engine cover. Refer to Engine Cover Replacement .
2. Loosen the exhaust manifold pipe clamp.
3. Slide the exhaust manifold pipe clamp down onto the pipe.
4. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .



5. Remove the catalytic converter to exhaust manifold pipe nuts.



6. Remove the exhaust manifold pipe hanger bracket nuts (2).
7. Remove the exhaust manifold pipe and hanger bracket from the vehicle.
8. Remove the exhaust manifold pipe hanger bracket from the manifold pipe.
9. Remove and discard the exhaust manifold pipe to catalytic converter gasket.

Installation Procedure

Notice: When inspecting or replacing exhaust system components, make sure there is adequate clearance from all points on the underbody to prevent overheating of the floor pan and possible damage to the passenger compartment insulation and trim materials.

1. Install a NEW gasket onto the exhaust manifold pipe studs.
2. Install the exhaust manifold pipe hanger bracket to the manifold pipe.
3. Position and install the exhaust manifold pipe and hanger bracket to the vehicle.

Notice: Refer to Fastener Notice in the Preface section.

4. Install the exhaust manifold pipe hanger bracket nuts (2).

Tighten
Tighten the nuts to 85 N·m (63 lb ft).




5. Install the catalytic converter to exhaust manifold pipe nuts.

Tighten
Tighten the nuts to 45 N·m (33 lb ft).

6. Lower the vehicle.



7. Slide the exhaust manifold pipe clamp up into position.
8. Tighten the exhaust manifold pipe clamp.

Tighten
Tighten the clamp to 12.5 N·m (106 lb in).

9. Install the engine cover. Refer to Engine Cover Replacement .