Muffler: Service and Repair

Muffler Replacement (6.0L, 6.6L, and 8.1L Engines)

Removal Procedure





1. Raise and suitably support the vehicle.
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, remove the exhaust muffler nuts.
11. Loosen the exhaust pipe clamp.
12. With the aid of an assistant, support the exhaust muffler.





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





15. If equipped with a 6.0L or 8.1L engine, remove the insulators from the frame hangers.
16. With the aid of an assistant, slide the muffler rearward in order to remove the muffler from the catalytic converter.
17. Remove the insulators from the muffler hangers.
18. Remove the exhaust manifold pipe gasket, if necessary.





19. If equipped with a 6.6L engine, remove the insulators from the frame hangers.
20. With the aid of an assistant, slide the muffler rearward in order to remove the muffler from the exhaust muffler pipe.
21. Remove the exhaust muffler gasket, if necessary.
22. Remove the insulators from the muffler hangers.





23. If equipped with a 6.0L or 8.1L engine, remove the oxygen sensor if the muffler is being replaced.
24. If the muffler is NOT being replaced as an assembly, the band clamp MUST be replaced. Perform the following:
1. Mark the position of the band clamp on the intermediate exhaust pipe.
2. Remove the band clamp from the exhaust pipe by grinding the weld.
3. Install a NEW band clamp onto the exhaust pipe.

Installation Procedure





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: Refer to Fastener Notice in Service Precautions.

3. Install the oxygen sensor.
Tighten the sensor to 42 Nm (31 ft. lbs.).





4. If equipped with a 6.6L engine, install the insulators to the muffler hangers.

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

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 insulators to the frame hangers.





8. If equipped with a 6.0L or 8.1L engine, install the insulators to the muffler hangers.

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

9. Install a new exhaust manifold pipe gasket.
10. With the aid of an assistant, slide the muffler forward in order to install the muffler to the catalytic converter.
11. Install the insulators to the frame hangers.





12. If equipped with a 6.6L engine, install the exhaust muffler nuts.
Tighten the nuts to 40 Nm (30 ft. lbs.).





13. If equipped with a 6.0L or 8.1L engine, position the NEW band clamp on the intermediate exhaust pipe, using the alignment mark created previously. The band clamp bolt must NOT be positioned below the exhaust pipe.
14. Install the exhaust muffler nuts.
15. Tighten the exhaust pipe clamp bolt.
^ Tighten the nuts to 40 Nm (30 ft. lbs.).
^ Tighten the clamp to 44 Nm (33 ft. lbs.).





16. Raise the rear axle using the adjustable jack stands, if necessary.
17. Install the rear shock absorbers lower bolts and nuts, if necessary.
Tighten the bolts to 95 Nm (70 ft. lbs.).





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





20. If equipped with a 8.6 or 9.5 inch ring gear, install the rear axle vent hose to the rear axle, if necessary.
21. Connect the vent hose swivel clip to the rear brake crossover pipe, if necessary.
22. Remove the adjustable jack stands from under the rear axle, if necessary.
23. Install the spare tire, if necessary.
24. Lower the vehicle.