GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2003 🢒 GMC Sierra Denali 🢒 Engine 🢒 Engine Exhaust 🢒 Exhaust Manifold Pipe Replacement

Exhaust Manifold Pipe Replacement 6.0, 6.6, and 8.1L Engines

Removal Procedure

Caution: Refer to Exhaust Service Caution in the Preface section.

Caution: Refer to Protective Goggles and Glove Caution in the Preface section.


    Object Number: 647997 Size: SH
  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Support the transmission with a suitable transmission jack.
  3. Remove the transmission mount to transmission support nuts.
  4. Raise the transmission off of the transmission support.

    5. Object Number: 788013 Size: SH
  5. Remove the transmission support crossmember bolts.
  6. Remove the transmission support crossmember.

    7. Object Number: 665520 Size: SH
  7. Depending on which side is being replaced, perform one of the following steps:
    8. • Remove the exhaust muffler nuts.
    • or
    • Loosen the exhaust pipe clamp.
  8. Remove the necessary exhaust system hangers so that the pipes can be separated.
  9. Use a jack stand to support the exhaust.

    10. Object Number: 664781 Size: SH
  10. If equipped with a 6.0, or 8.1L engine, perform the following:
    11. 10.1. Remove the clip around the engine harness and the oxygen sensor pigtail.
    10.2. Disconnect the connector position assurance (CPA) retainer.
    10.3. Disconnect the oxygen sensor electrical connector.
    10.4. Remove the oxygen sensor.

    Object Number: 858574 Size: SH
  11. if equipped with a 6.0, or 8.1L engine, remove the exhaust manifold pipe nuts.
  12. Using the transmission jack, lower the transmission slightly.

    13. Object Number: 694338 Size: SH
  13. If equipped with the 6.6L engine, remove the exhaust muffler nuts.

    14. Object Number: 668379 Size: SH
  14. If equipped with a 6.6L engine, loosen the exhaust pipe clamp.
  15. Slide the exhaust pipe clamp up onto the exhaust pipe adapter.

    16. Object Number: 858576 Size: SH
  16. If equipped with a 6.0, or 8.1L engine, remove the exhaust manifold pipe.
  17. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.
  18. Discard the exhaust manifold pipe seal.

    19. Object Number: 858590 Size: SH
  19. If equipped with a 6.0L engine, with regular production option (RPO) Y91, remove the exhaust manifold pipe.
  20. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.
  21. Discard the exhaust manifold pipe seal.

    22. Object Number: 694896 Size: SH
  22. If equipped with a 6.6L engine, remove the exhaust manifold pipe.
  23. Slide the exhaust manifold pipe hanger out of the exhaust pipe hanger bracket.

Installation Procedure

Notice: Refer to Exhaust System Inspection Notice in the Preface section.


    Object Number: 694896 Size: SH
  1. If equipped with a 6.6L engine, install the exhaust manifold pipe.
  2. Apply water based lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
  3. Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.

    4. Object Number: 858590 Size: SH
  4. If equipped with a 6.0L engine, with RPO Y91, install a new exhaust manifold pipe seal to the exhaust manifold pipe.
  5. Install the exhaust manifold pipe.
  6. Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
  7. Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.

    8. Object Number: 858576 Size: SH
  8. If equipped with a 6.0, or 8.1L engine, install a new exhaust manifold pipe seal to the exhaust manifold pipe.
  9. Install the exhaust manifold pipe.
  10. Apply lubricant to the exhaust pipe hanger bracket, in order to aid in installation.
  11. Slide the exhaust manifold pipe hanger into the exhaust pipe hanger bracket.

    12. Object Number: 694338 Size: SH
  12. If equipped with the 6.6L engine, install the exhaust muffler nuts until snug.

    13. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 668379 Size: SH

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

  13. If equipped with a 6.6L engine, slide the exhaust pipe clamp down and around the pipe connection.
  14. Tighten the exhaust pipe clamp and muffler nuts.

    15. Tighten

        • Tighten the clamp to 40 N·m (30 lb ft).
        • Tighten the nuts to 40 N·m (30 lb ft).

    Object Number: 858574 Size: SH
  15. If equipped with a 6.0L or 8.1 L engine, install the exhaust manifold pipe nuts.

    16. Tighten
    Tighten the nuts to 50 N·m (39 lb ft).

  16. Using the transmission jack, raise the transmission.

    17. Object Number: 664781 Size: SH
  17. If equipped with a 6.0, or 8.1L engine, and the exhaust manifold pipe was replaced perform the following:
    18. 17.1. Apply anti-seize compound GM P/N 12377953 or equivalent to the threads of the old oxygen sensor.
    17.2. Install the old oxygen sensor.

    Tighten
    Tighten the sensor to 42 N·m (31 lb ft).

  18. If equipped with a 6.0, or 8.1L engine, and the exhaust manifold pipe was not replaced perform the following:
    19. 18.1. Connect the oxygen sensor electrical connector.
    18.2. Connect the CPA retainer.
    18.3. Install the clip around the engine harness and the oxygen sensor pigtail.
  19. Install the exhaust pipe/catalytic converter to the vehicle.
  20. Install the exhaust system hangers.

    21. Object Number: 665520 Size: SH
  21. Depending on which side is being replaced, perform one of the following steps:
    22. • Install the exhaust muffler nuts.

    Tighten
    Tighten the nuts to 40 N·m (30 lb ft).

    • or
    • Install a NEW exhaust pipe clamp.

    Tighten
    Tighten the clamp to 44 N·m (33 lb ft).


    Object Number: 788013 Size: SH
  22. Install the transmission support crossmember.
  23. Install the transmission support crossmember bolts.

    24. Tighten
    Tighten the bolts to 95 N·m (70 lb ft).


    Object Number: 647997 Size: SH
  24. Lower the transmission onto the transmission support.
  25. Install the transmission mount to transmission support nuts.

    26. Tighten
    Tighten the bolts to 40 N·m (30 lb ft).

  26. Remove the support from the transmission.
  27. Lower the vehicle.