GM Service Manual Online
For 1990-2009 cars only

Exhaust Manifold Replacement RPO LSJ

Removal Procedure


    Object Number: 1649566  Size: SH
  1. Reposition the positive crankcase ventilation (PCV) vent hose clamps (1, 3) at the air cleaner outlet duct and the camshaft cover.
  2. Remove the PCV vent hose ends from the outlet duct and cover.
  3. Remove the PCV vent tube bolt (4) and nut (5).
  4. Remove the PCV vent hose/tube.

  5. Object Number: 1631387  Size: SH
  6. Remove the exhaust manifold heat shield studs (2).
  7. Remove the exhaust manifold heat shield (1).

  8. Object Number: 1389438  Size: SH
  9. Remove the heated oxygen sensor (HO2S) connector position assurance (CPA) retainer.
  10. Disconnect the engine harness electrical connector (1) from the HO2S.
  11. Remove the HO2S clip from the bracket on the thermostat housing.

  12. Object Number: 1631780  Size: SH
  13. Remove the HO2S.
  14. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .

  15. Object Number: 1650775  Size: SH

    Notice: Do not bend the exhaust flex decoupler more than 3 degrees in any direction. Movement of more than 3 degrees will damage the exhaust flex decoupler.

  16. Remove the catalytic converter to exhaust manifold nuts.
  17. Pull down and back on the exhaust pipe in order to separate the catalytic converter from the exhaust manifold.
  18. Remove and discard the catalytic converter gasket.
  19. Lower the vehicle.

  20. Object Number: 1631764  Size: SH
  21. Remove the exhaust manifold nuts.
  22. Remove the exhaust manifold.
  23. Remove and discard the exhaust manifold gasket.
  24. Clean and inspect all gasket mating surfaces.

Installation Procedure


    Object Number: 1631764  Size: SH
  1. Install a NEW exhaust manifold gasket onto the studs.
  2. Install the exhaust manifold.
  3. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1340643  Size: SH
  4. Install NEW exhaust manifold nuts.
  5. Tighten
    Tighten the nuts in the sequence shown to 14 N·m (10 lb ft).

  6. Raise and support the vehicle.

  7. Object Number: 1650775  Size: SH
  8. Install a NEW catalytic converter gasket .
  9. Install the catalytic converter to the exhaust manifold studs.
  10. Install the catalytic converter to exhaust manifold nuts.
  11. Tighten
    Tighten the nuts to 50 N·m (37 lb ft).

  12. Lower the vehicle.

  13. Object Number: 1631780  Size: SH
  14. If reinstalling the old HO2S, coat the threads with anti-seize compound G/M P/N 12377953, or equivalent.
  15. Install the HO2S.
  16. Tighten
    Tighten the sensor to 30 N·m (22 lb ft).


    Object Number: 1389438  Size: SH
  17. Connect the engine harness electrical connector (1) to the HO2S.
  18. Install the HO2S clip to the bracket on the thermostat housing.
  19. Install the HO2S CPA retainer.

  20. Object Number: 1631387  Size: SH
  21. Install the exhaust manifold heat shield (1).
  22. Install the exhaust manifold heat shield studs (2).
  23. Tighten
    Tighten the studs to 22 N·m (16 lb ft).


    Object Number: 1649566  Size: SH
  24. Install the PCV vent hose/tube.
  25. Install the PCV vent tube bolt (4) and nut (5).
  26. Tighten
    Tighten the bolt/nut to 10 N·m (89 lb in).

  27. Install the PCV vent hose ends to the outlet duct and cover.
  28. position the PCV vent hose clamps (1, 3) at the air cleaner outlet duct and the camshaft cover.

Exhaust Manifold Replacement RPO L61

Removal Procedure


    Object Number: 1650779  Size: SH
  1. Remove the intake manifold cover. Refer to Intake Manifold Cover Replacement .
  2. If equipped with regular production option (RPO) NU3, remove the secondary air injection (AIR) outlet hose/pipe bracket nut.
  3. Disconnect the AIR outlet hose/pipe quick connect fitting from AIR check valve. Refer to Plastic Collar Quick Connect Fitting Service .

  4. Object Number: 1650781  Size: SH
  5. If equipped with RPO NU3, remove the AIR outlet hose/pipe bracket bolt.
  6. Remove the AIR outlet hose/pipe bracket from the heat shield stud and reposition the hose/pipe out of the way.

  7. Object Number: 1631387  Size: SH
  8. Remove the exhaust manifold heat shield studs (2).
  9. Remove the exhaust manifold heat shield (1).

  10. Object Number: 1647986  Size: SH
  11. If equipped with regular production option (RPO) MN5, remove the heated oxygen sensor (HO2S) connector position assurance (CPA) retainer.
  12. Disconnect the engine harness electrical connector (2) from the HO2S.
  13. Remove the HO2S clip from the thermostat housing.

  14. Object Number: 1648166  Size: SH
  15. If equipped with RPO M86, remove the HO2S CPA retainer.
  16. Disconnect the engine harness electrical connector (1) from the HO2S.
  17. Remove the HO2S clip from the thermostat housing.

  18. Object Number: 1631780  Size: SH
  19. Remove the HO2S.
  20. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .

  21. Object Number: 1650780  Size: SH

    Notice: Do not bend the exhaust flex decoupler more than 3 degrees in any direction. Movement of more than 3 degrees will damage the exhaust flex decoupler.

  22. Remove the catalytic converter to exhaust manifold nuts.
  23. Pull down and back on the exhaust pipe in order to separate the catalytic converter from the exhaust manifold.
  24. Remove and discard the catalytic converter gasket.
  25. Lower the vehicle.

  26. Object Number: 1631764  Size: SH
  27. Remove the exhaust manifold nuts.
  28. Remove the exhaust manifold.
  29. Remove and discard the exhaust manifold gasket.
  30. Clean and inspect all gasket mating surfaces.

Installation Procedure


    Object Number: 1631764  Size: SH
  1. Install a NEW exhaust manifold gasket onto the studs.
  2. Install the exhaust manifold.
  3. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1340643  Size: SH
  4. Install NEW exhaust manifold nuts.
  5. Tighten
    Tighten the nuts in the sequence shown to 14 N·m (10 lb ft).

  6. Raise and support the vehicle.

  7. Object Number: 1650780  Size: SH
  8. Install a NEW catalytic converter gasket .
  9. Install the catalytic converter to the exhaust manifold studs.
  10. Install the catalytic converter to exhaust manifold nuts.
  11. Tighten
    Tighten the nuts to 50 N·m (37 lb ft).

  12. Lower the vehicle.

  13. Object Number: 1631780  Size: SH
  14. If reinstalling the old HO2S, coat the threads with anti-seize compound, or equivalent.
  15. Install the HO2S.
  16. Tighten
    Tighten the sensor to 42 N·m (31 lb ft).


    Object Number: 1648166  Size: SH
  17. If equipped with RPO M86, connect the engine harness electrical connector (1) to the HO2S.
  18. Install the HO2S clip to the thermostat housing.
  19. Install the HO2S CPA retainer.

  20. Object Number: 1647986  Size: SH
  21. If equipped with RPO MN5, connect the engine harness electrical connector (2) to the HO2S.
  22. Install the HO2S clip from the thermostat housing.
  23. Install the HO2S CPA retainer.

  24. Object Number: 1631387  Size: SH
  25. Install the exhaust manifold heat shield (1).
  26. Install the exhaust manifold heat shield studs (2).
  27. Tighten
    Tighten the studs to 22 N·m (16 lb ft).


    Object Number: 1650781  Size: SH
  28. If equipped with RPO NU3, position the AIR hose/pipe and install the bracket onto the heat shield stud.
  29. Position the AIR outlet hose/pipe bracket to the cylinder head.
  30. Install the AIR outlet hose/pipe bracket bolt.
  31. Tighten
    Tighten the bolt to 20 N·m (15 lb ft).


    Object Number: 1650779  Size: SH
  32. Connect the AIR outlet hose/pipe quick connect fitting to AIR check valve. Refer to Plastic Collar Quick Connect Fitting Service .
  33. Install the AIR outlet hose/pipe bracket nut.
  34. Tighten
    Tighten the nut to 10 N·m (89 lb in).

  35. Install the intake manifold cover. Refer to Intake Manifold Cover Replacement .

Exhaust Manifold Replacement RPO LE5

Removal Procedure


    Object Number: 1631387  Size: SH
  1. Remove the intake manifold cover. Refer to Intake Manifold Cover Replacement .
  2. Remove the exhaust manifold heat shield studs (2).
  3. Remove the exhaust manifold heat shield (1).

  4. Object Number: 1647986  Size: SH
  5. If equipped with regular production option (RPO) MN5, remove the heated oxygen sensor (HO2S) connector position assurance (CPA) retainer.
  6. Disconnect the engine harness electrical connector (2) from the HO2S.
  7. Remove the HO2S clip from the thermostat housing.

  8. Object Number: 1648166  Size: SH
  9. If equipped with RPO M86, remove the HO2S CPA retainer.
  10. Disconnect the engine harness electrical connector (1) from the HO2S.
  11. Remove the HO2S clip from the thermostat housing.

  12. Object Number: 1631780  Size: SH
  13. Remove the HO2S.
  14. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .

  15. Object Number: 1650757  Size: SH

    Notice: Do not bend the exhaust flex decoupler more than 3 degrees in any direction. Movement of more than 3 degrees will damage the exhaust flex decoupler.

  16. Remove the catalytic converter to exhaust manifold nuts.
  17. Pull down and back on the exhaust pipe in order to separate the catalytic converter from the exhaust manifold.
  18. Remove and discard the catalytic converter gasket.
  19. Lower the vehicle.

  20. Object Number: 1631764  Size: SH
  21. Remove the exhaust manifold nuts.
  22. Remove the exhaust manifold.
  23. Remove and discard the exhaust manifold gasket.
  24. Clean and inspect all gasket mating surfaces.

Installation Procedure


    Object Number: 1631764  Size: SH
  1. Install a NEW exhaust manifold gasket onto the studs.
  2. Install the exhaust manifold.
  3. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1340643  Size: SH
  4. Install NEW exhaust manifold nuts.
  5. Tighten
    Tighten the nuts in the sequence shown to 14 N·m (10 lb ft).

  6. Raise and support the vehicle.

  7. Object Number: 1650757  Size: SH
  8. Install a NEW catalytic converter gasket .
  9. Install the catalytic converter to the exhaust manifold studs.
  10. Install the catalytic converter to exhaust manifold nuts.
  11. Tighten
    Tighten the nuts to 50 N·m (37 lb ft).

  12. Lower the vehicle.

  13. Object Number: 1631780  Size: SH
  14. If reinstalling the old HO2S, coat the threads with anti-seize compound or equivalent.
  15. Install the HO2S.
  16. Tighten
    Tighten the sensor to 42 N·m (31 lb ft).


    Object Number: 1648166  Size: SH
  17. If equipped with RPO M86, connect the engine harness electrical connector (1) to the HO2S.
  18. Install the HO2S clip to the thermostat housing.
  19. Install the HO2S CPA retainer.

  20. Object Number: 1647986  Size: SH
  21. If equipped with RPO MN5, connect the engine harness electrical connector (2) to the HO2S.
  22. Install the HO2S clip from the thermostat housing.
  23. Install the HO2S CPA retainer.

  24. Object Number: 1631387  Size: SH
  25. Install the exhaust manifold heat shield (1).
  26. Install the exhaust manifold heat shield studs (2).
  27. Tighten
    Tighten the studs to 22 N·m (16 lb ft).

  28. Install the intake manifold cover. Refer to Intake Manifold Cover Replacement .