Muffler: Service and Repair

Muffler Replacement

Removal Procedure

Caution: Refer to Protective Goggles and Gloves Caution in Service Precautions.

Caution: Refer to Exhaust Service Caution in Service Precautions.

Important: The muffler is serviced as one complete unit with an exhaust pipe and tail pipe. Some variations of vehicles may have an aftermarket tail pipe added.
When the vehicle is raised on the hoist it must be raised by the frame to allow the rear axle to be lowered.





1. Raise the vehicle. Refer to Vehicle Lifting.
2. If equipped with 4.3L, 5.0L, or 5.7L engine with a single catalytic converter pipe, remove the nuts retaining the catalytic converter pipe from the muffler flange.





3. If equipped with 5.0L or 5.7L engine with dual catalytic converter pipes or an 8.1L engine, loosen the clamp for the right catalytic converter.
4. Remove the nuts retaining the left catalytic converter to the muffler flange.





5. If equipped with 6.5L engine, remove the nuts retaining the exhaust pipe to the muffler flange.





Important: Depending on the wheel base of the vehicle and the length of the exhaust system the following procedures are required in order to remove the muffler assembly from the vehicle.

6. If equipped with 4.3L, 5.0L, and 5.7L engine with 135 inch wheel base and full body style, remove the muffler assembly hanger pins from the exhaust hanger insulators. Due to the weight of the exhaust system it may take 2 persons.
7. Remove the muffler assembly by lifting over the rear axle and remove towards the front of the vehicle.





8. If equipped with 4.3L, 5.0L, 5.7L, 6.5L, and 8.1L engine with 155 inch wheel base and full body style, support the right side of the rear axle with a suitable jack stand. Relieve the tension from the shock absorber.
9. Remove the right lower shock absorber bolt and nut.
10. Lower the axle.





11. Remove the muffler assembly hanger pins from the exhaust hanger insulators. Due to the weight of the exhaust system it may take 2 persons.
12. Remove the muffler assembly by lifting over the rear axle and remove towards the front of the vehicle.





13. If equipped with 5.7L, 6.5L, or 8.1L engine and a 139 inch, 159 inch, or 177 inch wheel base with a cutaway body style, support the rear axle in order to relieve the tension from the rear springs, using a suitable jack stand.
14. Remove the tire and wheel assembly.
15. Remove the following parts for the right rear spring from the axle:
^ The rear spring U-bolts and nuts (1)
^ The anchor plate





16. Remove the right lower shock absorber bolt and nut.
17. Lower the axle.





18. Remove the muffler assembly hanger pins from the exhaust hanger insulators. Due to the weight of the exhaust system it may take 2 persons.
19. Remove the muffler assembly by lifting over the rear axle and remove towards the rear of the vehicle.

Installation Procedure





1. If equipped with 4.3L, 5.0L, and 5.7L engine with 135 inch wheel base and full body style, install the muffler assembly from the front of the vehicle by lifting over the rear axle. Due to the weight of the exhaust system it may take 2 persons.
2. Install the muffler assembly hanger pins to the exhaust hanger insulators.





3. If equipped with 4.3L, 5.0L, 5.7L, 6.5L, and 8.1 L engine with 155 inch wheel base and full body style, install the muffler assembly from the front of the vehicle by lifting over the rear axle. Due to the weight of the exhaust system it may take 2 persons.
4. Install the muffler assembly hanger pins to the exhaust hanger insulators.





5. Raise the rear axle with a suitable jack.

Notice: Refer to Fastener Notice in Service Precautions.





6. Install the lower shock absorber bolt and the lower shock absorber nut to the axle.
^ Tighten the lower shock absorber nut and the lower shock absorber bolt to 80 Nm (59 ft. lbs.).
7. Remove the jackstand from the rear axle.
8. If equipped with 5.7L, 6.5L, or 8.1L engine and a 139 inch, 159 inch, or 177 inch wheel base with a cutaway body style, install the muffler assembly from the rear of the vehicle by lifting over the rear axle. Due to the weight of the exhaust system it may take 2 persons.
9. Install the muffler assembly hanger pins to the exhaust hanger insulators.





10. Raise the right side of the rear axle with a suitable jack.
11. Install the lower shock absorber bolt and the lower shock absorber nut to the axle.
^ Tighten the lower shock absorber nut and the lower shock absorber bolt to 80 Nm (59 ft. lbs.).





12. Install the right rear spring anchor plate.
13. Install the spring U-bolts.

Important: Tighten the outer U-Bolt nuts and then tighten the inner U-Bolt nuts (1) to 25 Nm (18 ft. lbs.). Then tighten the U-Bolt nuts (1) in a cross pattern sequence as shown.

14. Install the U-bolt nuts.
^ For vehicles below 7300 GVW, tighten the U-bolt nuts to 95 Nm (70 ft. lbs.).
- For vehicles above 7300 GVW, tighten the U-bolt nuts to 150 Nm (111 ft. lbs.).





15. Install the tire and wheel.
16. If equipped with 4.3L, 5.0L, or 5.7L engine with a single catalytic converter pipe, install the retaining nuts and new gasket to the front of the muffler.
^ Tighten the catalytic converter to muffler retaining nuts to 48 Nm (35 ft. lbs.).





17. If equipped with 5.0L or 5.7L engine with dual catalytic converter pipes or an 8.1L engine, install the right catalytic converter in the muffler.
18. Install a new gasket and the nuts retaining the left catalytic converter to the muffler flange.
^ Verify that the exhaust system is properly aligned and tighten the right catalytic converter clamp to 54 Nm (40 ft. lbs.).
^ Tighten the catalytic converter to the muffler flange nuts to 48 Nm (35 ft. lbs.).





19. If equipped with 6.5L engine, install a new gasket and the nuts retaining the exhaust pipe to the muffler flange.
^ Tighten the flange nuts to 48 Nm (35 ft. lbs.).

Notice: Refer to Exhaust System Inspection Notice in Service Precautions.

20. Verify the exhaust system for proper clearance and the alignment of all components.
21. Lower the vehicle.