Muffler: Service and Repair

Muffler Replacement (6.01- and 8.1. Engines)

- Tools Required
- J 38185 Hose Clamp Pliers

Removal Procedure





1. Remove the rear tires and wheels. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
2. Remove the oil pan skid plate bolts and plate, if necessary.
3. Remove the spare tire.





4. If servicing a vehicle with regular production option (RPO) Z55, disconnect the chassis harness from the following electrical connectors:
- Electronic suspension rear position sensor (1)
- Rear shock (2)

Important: Do not attempt to pry the rear suspension sensor link rods from the rear position sensor ball studs.

5. Remove the left and right sensor link rods from the sensors, perform the following:
5.1. Support the sensor lever with your hand
5.2. Twist the link rod in order to remove it from the ball stud
6. Install adjustable jack stands under the rear axle.





7. If equipped with a 8.6 or 9.5 inch ring gear, remove the rear axle vent hose from the rear axle, it necessary.
8. Remove the vent hose swivel clip from the rear brake crossover pipe.





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





11. Remove the rear shock absorbers lower bolts and nuts.
12. Lower the rear axle slightly, using the adjustable jack stands, in order to remove the muffler.





13. Unclip the oxygen sensor connector from the frame.
14. Disconnect the connector position assurance (CPA) retainer.
15. Disconnect the oxygen sensor electrical connector,





16. Unclip the oxygen sensor connector from the support.
17. Disconnect the CPA retainer.
18. Disconnect the oxygen sensor electrical connector.





19. Unclip the oxygen sensor connector from the support.
20. Disconnect the CPA retainer.
21. Disconnect the oxygen sensor electrical connector.





22. If equipped with a 6.01- engine, perform the following:
- Unclip the oxygen sensor connector from the frame.
- Disconnect the CPA retainer.
- Disconnect the oxygen sensor electrical connector.





23. Remove the exhaust muffler nuts.
24. Loosen the exhaust pipe clamp.
25. With the aid of an assistant, support the exhaust muffler.





26. Remove the insulators from the frame hangers.
27. With the aid of an assistant, slide the muffler rearward in order to remove the muffler from the catalytic converter.
28. Remove the insulators from the muffler hangers.
29. Remove the exhaust manifold pipe gasket.





30. Remove the oxygen sensor it the muffler is being replaced.

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 Cautions and Notices.

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





10. If equipped with a 6.01- engine, perform the following:
- Connect the oxygen sensor electrical connector.
- Connect the CPA retainer.
- Clip the oxygen sensor connector to the frame.





11. Connect the oxygen sensor electrical connector.
12. Connect the CPA retainer.
13. Clip the oxygen sensor connector to the support.





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





17. Connect the oxygen sensor electrical connector.
18. Connect the CPA retainer.
19. Clip the oxygen sensor connector to the frame.





20. Raise the rear axle using the adjustable jack stands.
21. Install the rear shock absorbers lower bolts and nuts.
- Tighten the lower bolts to 95 Nm (70 ft. lbs.).
22. Remove the adjustable jack stands from under the rear axle.





23. If equipped with a 10.5 inch ring gear, connect the vent hose swivel clip to the rear brake crossover pipe.
24. Install the rear axle vent hose to the rear axle, if necessary.





25. If equipped with a 8.6 or 9.5 inch ring gear, connect the vent hose swivel clip to the rear brake crossover pipe.
26. Install the rear axle vent hose to the rear axle, if necessary.





27. If servicing a vehicle equipped with RPO Z55, install the left and right sensor link rods to the sensors. Using J 38185 install the link rods to the ball studs on the sensor levers.
28. Connect the chassis harness to the following electrical connectors:
- Electronic suspension rear position sensor (1)
- Rear shock (2)
29. Install the spare tire.





30. Install the oil pan skid plate and bolts, if necessary.
- Tighten the bolts to 20 Nm (15 ft. lbs.).
31. Install the rear tires and wheels. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.