Exhaust Muffler Replacement 4.3L, 4.8L, and 5.3L Engines

1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Remove the exhaust muffler nuts.



3. Apply lubricant to the exhaust insulators in order to aid in removal.
4. Remove the muffler brackets from the insulators.
5. Remove the exhaust muffler.

1. Apply lubricant to the exhaust insulators in order to aid in installation.
2. Install the muffler to the insulators.




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.

3. Install the exhaust muffler nuts.

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

Exhaust Muffler Replacement 6.0L, 6.6L, and 8.1L Engines

Important: Depending on vehicle configuration, the rear axle may need to be lowered in order to remove the exhaust muffler assembly.

1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Remove the spare tire, if necessary.
3. Install adjustable jack stands under the rear axle, if necessary.
4. If equipped with a 8.6 or 9.5 inch ring gear, remove the rear axle vent hose from the rear axle, if necessary.
5. Remove the vent hose swivel clip from the rear brake crossover pipe, if necessary.



6. If equipped with a 10.5 inch ring gear, remove the rear axle vent hose from the rear axle, if necessary.
7. Remove the vent hose swivel clip from the rear brake crossover pipe, if necessary.



8. Remove the rear shock absorbers lower bolts and nuts, if necessary.
9. Lower the rear axle using the adjustable jack stands, if necessary.



10. If equipped with a 6.0L or 8.1L engine, perform the following:

•	Unclip the oxygen sensor connector from the frame.

•	Disconnect the connector position assurance (CPA) retainer.

•	Disconnect the oxygen sensor electrical connector.




11. If equipped with a 6.0L or 8.1L engine, perform the following:

•	Unclip the oxygen sensor connector from the support.

•	Disconnect the CPA retainer.

•	Disconnect the oxygen sensor electrical connector.




12. If equipped with a 6.0L or 8.1L engine, perform the following:

•	Unclip the oxygen sensor connector from the support.

•	Disconnect the CPA retainer.

•	Disconnect the oxygen sensor electrical connector.




13. If equipped with a 6.0L engine, perform the following:

•	Unclip the oxygen sensor connector from the frame.

•	Disconnect the CPA retainer.

•	Disconnect the oxygen sensor electrical connector.




14. If equipped with a 6.0L or 8.1L engine, remove the exhaust muffler nuts.
15. Loosen the exhaust pipe clamp.
16. With the aid of an assistant, support the exhaust muffler.



17. If equipped with a 6.6L engine, remove the exhaust muffler nuts.
18. With the aid of an assistant, support the exhaust muffler.



19. If equipped with a 6.0L or 8.1L engine, remove the insulators from the muffler hangers.
20. With the aid of an assistant, slide the muffler rearward in order to separate the muffler from the catalytic converter.
21. Remove the insulators from the hangers, if necessary.
22. Remove the exhaust manifold pipe gasket, if necessary.



23. If equipped with a 6.0L engine, with regular production option (RPO) Y91, remove the insulator from the muffler hanger.



24. If equipped with a 6.0L engine, with RPO Y91, remove the insulators from the muffler hangers.
25. With the aid of an assistant, slide the muffler rearward in order to separate the muffler from the catalytic converter.
26. Remove the insulators from the hangers, if necessary.
27. Remove the exhaust manifold pipe gasket, if necessary.



28. If equipped with a 6.6L engine, remove the insulators from the muffler hangers.
29. With the aid of an assistant, slide the muffler rearward in order to separate the muffler from the exhaust muffler pipe.
30. Remove the insulators from the muffler hangers, if necessary.
31. Remove the exhaust muffler gasket, if necessary.



32. If equipped with a 6.0L or 8.1L engine, remove the oxygen sensor if the muffler is being replaced.

1. If equipped with a 6.0L or 8.1L engine, and the muffler was replaced re-install the old oxygen sensor.
2. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensor.

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.

3. Install the oxygen sensor.

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





Important: Apply lubricant to the insulators to aid in installation.

4. If equipped with a 6.6L engine, install the insulators to the hangers, if necessary.
5. Install a new exhaust muffler gasket.
6. With the aid of an assistant, slide the muffler forward in order to install the muffler to the exhaust muffler pipe.
7. Install the muffler hangers to the insulators.




Important: Apply lubricant to the insulators to aid in installation.

8. If equipped with a 6.0L engine, with RPO Y91, install the insulators to the muffler hangers.
9. Install a new exhaust muffler gasket.
10. With the aid of an assistant, slide the muffler forward in order to install the muffler to the exhaust muffler pipe.
11. Install the insulators to the frame hangers.



12. If equipped with a 6.0L engine, with RPO Y91, install the insulator to the hanger.




Important: Apply lubricant to the insulators to aid in installation.

13. If equipped with a 6.0L or 8.1L engine, install the insulators to the muffler hangers.
14. Install a new exhaust manifold pipe gasket.
15. With the aid of an assistant, slide the muffler forward in order to install the muffler to the catalytic converter.
16. Install the muffler hangers to the insulators.



17. If equipped with a 6.6L engine, install the exhaust muffler nuts.

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




18. If equipped with a 6.0L or 8.1L engine, install the exhaust muffler nuts.
19. Tighten the exhaust pipe clamp bolt.

Tighten

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

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




20. If equipped with a 6.0L engine, perform the following:

•	Connect the oxygen sensor electrical connector.

•	Connect the CPA retainer.

•	Clip the oxygen sensor connector to the frame.




21. If equipped with a 6.0 L or 8.1 L engine, perform the following:

•	Connect the oxygen sensor electrical connector.

•	Connect the CPA retainer.

•	Clip the oxygen sensor connector to the support.




22. If equipped with a 6.0L or 8.1L engine, perform the following:

•	Connect the oxygen sensor electrical connector.

•	Connect the CPA retainer.

•	Clip the oxygen sensor connector to the support.




23. If equipped with a 6.0L or 8.1L engine, perform the following:

•	Connect the oxygen sensor electrical connector.

•	Connect the CPA retainer.

•	Clip the oxygen sensor connector to the frame.




24. Raise the rear axle using the adjustable jack stands, if necessary.
25. Install the rear shock absorbers lower bolts and nuts, if necessary.

Tighten
Tighten the rear shock absorbers lower bolts to 95 N·m (70 lb ft).




26. If equipped with a 10.5 inch ring gear, install the rear axle vent hose to the rear axle, if necessary.
27. Connect the vent hose swivel clip to the rear brake crossover pipe, if necessary.



28. If equipped with a 8.6 or 9.5 inch ring gear, install the rear axle vent hose to the rear axle, if necessary.
29. Connect the vent hose swivel clip to the rear brake crossover pipe, if necessary.
30. Remove the adjustable jack stands from under the rear axle, if necessary.
31. Install the spare tire, if necessary.
32. Lower the vehicle.