Exhaust Manifold Pipe Replacement 6.6L and 8.1L

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. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. If equipped with the 8.1L engine, remove the exhaust muffler. Refer to Muffler Replacement .



3. If equipped with a 8.1L engine, perform the following:

3.1.	Remove the clip around the engine harness and the oxygen sensors pigtail.

3.2.	Disconnect the connector position assurance (CPA) retainers.

3.3.	Disconnect the oxygen sensors electrical connector.

3.4.	If replacing the exhaust manifold pipe, remove the oxygen sensors.




4. if equipped with a 8.1L engine, remove the exhaust manifold pipe nuts.



5. If equipped with the 6.6L engine, remove the exhaust.



6. If equipped with a 6.6L engine, loosen the exhaust pipe clamp.
7. Slide the exhaust pipe clamp up onto the exhaust pipe adapter.



8. If equipped with a 8.1L engine, remove the exhaust manifold pipe.
9. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.
10. Discard the exhaust manifold pipe seal.



11. If equipped with a 6.6L engine, remove the exhaust manifold pipe.
12. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket, discard gasket.

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. If equipped with a 6.6L engine, install the exhaust manifold pipe.
2. Apply water based lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
3. Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.



4. If equipped with a 8.1L engine, install a new exhaust manifold pipe seal to the exhaust manifold pipe.
5. Install the exhaust manifold pipe.
6. Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
7. Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.



8. If equipped with the 6.6L engine, install the exhaust .




Important: Ensure that the manifold pipe is square to the exhaust pipe adapter.

9. If equipped with a 6.6L engine, slide the exhaust pipe clamp down and around the pipe connection.

Notice: Refer to Fastener Notice in the Preface section.

10. Tighten the exhaust pipe clamp and muffler nuts.

Tighten

•	Tighten the exhaust pipe clamp to 40 N·m (30 lb ft).

•	Tighten the exhaust muffler nuts to 40 N·m (30 lb ft).




11. If equipped with a 8.1L engine, install the exhaust manifold pipe nuts.

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




12. If equipped with a 8.1L engine, and the exhaust manifold pipe was replaced perform the following:

12.1.

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

12.2.

Install the old oxygen sensor.

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

13. If equipped with a 8.1L engine, and the exhaust manifold pipe was not replaced perform the following:

13.1.

Connect the oxygen sensor electrical connector.

13.2.

Connect the CPA retainer.

13.3.

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

14. If equipped with the 8.1L engines, install the exhaust muffler. Refer to Muffler Replacement .
15. Lower the vehicle.

Exhaust Manifold Pipe Replacement 7.8L and 7.2L CAT

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.

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).