Installation Procedure

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

If equipped with a 6.6L engine, install the exhaust manifold pipe.

Fig 1: Exhaust Manifold Pipe Hanger And Insulator (6.0L, 6.6L, and 8.1L Engines)
Courtesy of GENERAL MOTORS CORP.
Apply water based lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.

Fig 2: Exhaust Manifold Pipe (6.0L, With RPO Y91)

GM858590

Courtesy of GENERAL MOTORS CORP.

If equipped with a 6.0L engine, with RPO Y91, install a new exhaust manifold pipe seal to the exhaust manifold pipe.
Install the exhaust manifold pipe.
Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.

Fig 3: Exhaust Manifold Pipe (6.0L, 6.6L, and 8.1L Engines)

GM858576

Courtesy of GENERAL MOTORS CORP.

If equipped with a 6.0L or 8.1L engine, install a new exhaust manifold pipe seal to the exhaust manifold pipe.
Install the exhaust manifold pipe.
Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.

Fig 4: Exhaust Muffler Nuts (6.0L, 6.6L, and 8.1L Engines)

GM694338

Courtesy of GENERAL MOTORS CORP.

If equipped with the 6.6L engine, install the exhaust muffler nuts until snug.

Fig 5: View Of Turbocharger Exhaust Pipe & Clamp

GM668379

Courtesy of GENERAL MOTORS CORP.

IMPORTANT: Ensure that the manifold pipe is square to the exhaust pipe adapter.

NOTE: Refer to Fastener Notice in Cautions and Notices.

If equipped with a 6.6L engine, slide the exhaust pipe clamp down and around the pipe connection.
Tighten the exhaust pipe clamp and muffler nuts.
Tighten:
- Tighten the clamp to 40 N.m (30 lb ft).
- Tighten the nuts to 40 N.m (30 lb ft).

Fig 6: Exhaust Manifold Pipe Nuts (6.0L, 6.6L, and 8.1L Engines)

GM858574

Courtesy of GENERAL MOTORS CORP.

If equipped with a 6.0L or 8.1L engine, install the exhaust manifold pipe nuts.
Tighten: Tighten the nuts to 50 N.m (39 lb ft).
Using the transmission jack, raise the transmission.

Fig 7: View Of O2 Sensor, Connector, Harness And Retainers

GM664781

Courtesy of GENERAL MOTORS CORP.

If equipped with a 6.0L or 8.1L engine, and the exhaust manifold pipe was replaced perform the following:
1. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensor.
2. Install the old oxygen sensor.
  Tighten: Tighten the sensor to 42 N.m (31 lb ft).
If equipped with a 6.0L or 8.1L engine, and the exhaust manifold pipe was not replaced perform the following:
1. Connect the oxygen sensor electrical connector.
2. Connect the CPA retainer.
3. Install the clip around the engine harness and the oxygen sensor pigtail.
If equipped with a 6.0L or 8.1L engine, remove the exhaust muffler. Refer to Muffler Replacement (4.3L, 4.8L, and 5.3L Engines) or Muffler Replacement (6.0L, 6.6L, and 8.1L Engines) .
Install the transmission support crossmember.

Fig 8: Transmission Support Crossmember (6.0L, 6.6L, and 8.1L Engines)
Courtesy of GENERAL MOTORS CORP.
Install the transmission support crossmember bolts.
Tighten: Tighten the bolts to 95 N.m (70 lb ft).

Fig 9: Identifying Transmission Mount Nuts

GM647997

Courtesy of GENERAL MOTORS CORP.

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.
Lower the vehicle.