| Subject: | Exhaust Moan/Vibration (Replace Converter Assembly and Exhaust Muffler Assembly) | 
| Models: | 2004-2005 Chevrolet Silverado 2500HD/3500HD Series Crew Cab Short Box Pickups | 
 | 2004-2005 GMC Sierra 2500HD/3500HD Series Crew Cab Short Box Pickups | 
 | with 6.6L Diesel Engine (VIN 2 -- RPO LLY) | 
 
Condition
Some customers may comment on a moan or vibration at vehicle speeds approximately 87-97 km/h (55-60 mph) and at approximately 1700-1800 RPM.
Correction
Replace the catalytic converter assembly and exhaust muffler assembly using the procedure listed below.
- Raise and suitably support the vehicle.
 
- Remove the spare tire. 
 
- Install adjustable jack stands under the rear axle.
 
- Remove the rear axle vent  hose from the rear axle.
 
- Remove the vent hose swivel clip from the rear brake crossover pipe.
 
- Remove the rear shock absorbers lower bolts and nuts. 
 
- Lower the rear axle using the adjustable jack stands. 
 
- Loosen the catalytic converter coupling nuts.
 
- With the aid of an assistant, support the exhaust muffler.
 
- Gently pry up the catalytic converter coupling clip (1) (on the muffler end) in order to disengage the locator button (3) from the coupling clip.
 
- With the aid of an assistant, slide the muffler rearward until the locator button is fully disengaged.
 
- Remove the insulators from the frame hangers.
 
- With the aid of an assistant, remove the muffler assembly from the vehicle.
 
- Support the transmission with a suitable transmission jack.
 
- Remove the transmission mount to transmission support nuts.
 
- Raise the transmission off of the transmission support.
 
- Remove the transmission support crossmember bolts.
 
- Remove the transmission support crossmember.
 
- Loosen the exhaust pipe clamp.
 
- Slide the exhaust pipe clamp up onto the exhaust pipe.
 
- Slide the catalytic converter hanger out of the insulator.
 
- Remove the catalytic converter.
 
- Apply water based lubricant to the exhaust pipe hanger bracket, in order  to aid in installation.
 
- Slide the catalytic converter hanger into the insulator.
 
Important: Ensure that the manifold pipe is square to the exhaust pipe adapter.
- Slide the exhaust pipe clamp down and around the pipe connection.
 
- Tighten the exhaust pipe clamp.
 
Tighten
Tighten the clamp to 40 N·m (30 lb ft).
- Lower the transmission onto the transmission support.
 
- Install the transmission mount to transmission support nuts.
 
Tighten
Tighten the bolts to 40 N·m (30 lb ft).
- Remove the support from the transmission.
 
- With the aid of an assistant, align the new muffler, locator button (3) to the catalytic converter coupling groove (2).
 
- Install the muffler until the locator button is fully engaged by the coupling clip (1).
 
Important: Apply lubricant to the insulators to aid in installation.
- Install the insulators to the frame hangers.
 
- Tighten the catalytic converter coupling nuts until snug.
 
- Once snug, tighten the catalytic converter coupling nuts.
 
Tighten
Tighten the nuts to 45 N·m (33 lb ft).
- Raise the rear axle using the adjustable jack stands.
 
- Install the rear shock absorbers lower bolts and nuts.
 
Tighten
Tighten the bolts to 95 N·m (70 lb ft).
- Install the rear axle vent hose to the rear axle.
 
- Connect the vent hose swivel clip to the rear brake crossover pipe.
 
- Remove the adjustable jack stands from under the rear axle.
 
- Install the spare tire.
 
- Lower the vehicle.
 
Parts Information
Part Number 
 | Description 
 | Qty 
 | 
15229341 
 | Converter Asm. -- Oxidation Catalytic 
 | 1 
 | 
15229356 
 | Muffler Asm. -- Exhaust 
 | 1 
 | 
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation 
 | Description 
 | Labor Time 
 | 
L9707* 
 | Exhaust System (Complete) - Replace 
 | 1.6 hrs 
 | 
*This is a unique labor operation number for bulletin use only. This number will not be published in the Labor Time Guide.