Muffler: Service and Repair

Muffler Replacement (6.0L and 8.1L Engines)

Removal Procedure
1. Raise and suitably support the vehicle. Refer to Vehicle Lifting.
2. Unclip the oxygen sensor connector from the frame.





3. Disconnect the Connector Position Assurance (CPA) retainer.
4. Disconnect the oxygen sensor electrical connector.





5. Unclip the oxygen sensor connector from the support.
6. Disconnect the CPA retainer.
7. Disconnect the oxygen sensor electrical connector.





8. Unclip the oxygen sensor connector from the support.
9. Disconnect the CPA retainer.
10. Disconnect the oxygen sensor electrical connector.





11. 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.





12. Remove the exhaust muffler nuts.
13. Loosen the exhaust pipe clamp.
14. With the aid of an assistant, support the exhaust muffler.





15. 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.





19. Remove the oxygen sensor if the muffler is being replaced.
20. If the muffler is NOT being replaced as an assembly, the band clamp MUST be replaced. Perform the following:
20.1. Mark the position of the band clamp on the intermediate exhaust pipe.
20.2. Remove the band clamp from the exhaust pipe by grinding the weld.
20.3. Install a NEW band clamp onto the exhaust pipe.

Installation Procedure
1. If the muffler was replaced reinstall 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 oxygen sensor to 42 Nm (31 ft. lbs.).





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

4. Install the insulators to the muffler hangers.
5. Install a new exhaust manifold pipe gasket.
6. With the aid of an assistant, slide the muffler forward in order to install the muffler to the catalytic converter.
7. Install the insulators to the frame hangers.
8. Lower the vehicle.





9. 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.
10. Install the exhaust muffler nuts, until snug.
11. Tighten the exhaust pipe clamp bolt and muffler nuts.
- Tighten the nuts to 40 Nm (30 ft. lbs.).
- Tighten the clamp to 44 Nm (33 ft. lbs.).





12. 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.





13. Connect the oxygen sensor electrical connector.
14. Connect the CPA retainer.
15. Clip the oxygen sensor connector to the support.





16. Connect the oxygen sensor electrical connector.
17. Connect the CPA retainer.
18. Clip the oxygen sensor connector to the support.





19. Connect the oxygen sensor electrical connector.
20. Connect the CPA retainer.
21. Clip the oxygen sensor connector to the frame.