Bonneville, LeSabre, Park Avenue 2000-2005

Exhaust Manifold

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Removal & Installation



3.8L Engine
Front Manifold

NOTE
NC8 refers to vehicles with California Ultra Low Emission Vehicle package.



Click image to see an enlarged view

Fig. Exploded view of the left exhaust manifold mounting

  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Spark plug wires
     
    Engine oil dipstick and tube
     
    Left side lift bracket, if necessary
     
    2 bolts attaching the left exhaust manifold to the crossover pipe
     
    Exhaust manifold
     

  4.  

To install:

  1. Install or connect the following:

    Exhaust manifold with a new gasket. Torque the studs and bolts gradually and evenly to 22 ft. lbs. (30 Nm).
     
    2 bolts attaching the left exhaust manifold to the crossover pipe. Torque the bolts to 15 ft. lbs. (20 Nm).
     
    Left side lift bracket, if removed
     
    Engine oil dipstick and tube. Torque the bolts to 15 ft. lbs. (20 Nm).
     
    Spark plug wires
     
    Negative battery cable
     

  2.  
  3. Run the engine and check for exhaust leaks.
  4.  

Right Side (Rear) Manifold-Models With Nc8
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Air cleaner assembly
     
    Fuel injector sight shield
     
    Heated Oxygen (HO 2 S) sensor electrical connection
     
    Spark plug wires
     
    Connector from the secondary AIR valve
     
    Hose from the secondary AIR valve
     
    Bolts attaching the secondary AIR tube to the exhaust manifold
     
    Secondary AIR tube and the gasket from the exhaust manifold and discard the gasket
     
    Bolt attaching the secondary AIR valve to the fuel injector sight shield bracket
     
    Secondary AIR valve from the fuel injector sight shield bracket
     
    Brake booster heat shield
     
    Crossover pipe
     
    Transaxle fluid dipstick and tube
     
    Exhaust manifold pipe
     
    Right exhaust manifold studs
     
    Fuel injector sight shield bracket retaining nuts and the bracket
     
    Right engine lift bracket retaining fasteners and the bracket
     
    Bolt attaching the Exhaust Gas Recirculation (EGR) inlet pipe to the right exhaust manifold
     
    Right exhaust manifold retaining fasteners
     
    Right exhaust manifold and the gasket from the engine and discard the gasket
     
    Exhaust crossover seal from the exhaust crossover and discard the seal
     

  4.  

To install:

  1. Install or connect the following:

    New exhaust crossover seal
     
    New manifold gasket
     
    Manifold to the cylinder head and crossover pipe
     
    Manifold mounting studs. Torque the studs and bolts to 22 ft. lbs. (30 Nm), beginning at the center and working outwards.
     
    Bolt attaching the Exhaust Gas Recirculation (EGR) inlet pipe to the right exhaust manifold and tighten to 22 ft. lbs. (30 Nm)
     
    Engine lift bracket
     
    Fuel injector sight shield bracket and tighten the retainers to 22 ft. lbs. (30 Nm)
     
    Right exhaust manifold studs and tighten to 80 inch lbs. (9 Nm)
     
    HO 2 S sensor, if removed
     
    Exhaust manifold pipe
     
    Transmission dipstick tube
     
    Exhaust crossover to the right exhaust manifold bolts and tighten to 15 ft. lbs. (20 Nm)
     
    Brake booster heat shield
     
    Air cleaner assembly
     
    Secondary AIR valve to the fuel injector sight shield bracket and tighten the bolt to 18 ft. lbs. (25 Nm)
     
    New gasket on the secondary AIR tube
     
    Bolts attaching the secondary AIR tube to the exhaust manifold and tighten to 89 inch lbs. (10 Nm)
     
    Hose to the secondary AIR valve
     
    Connector to the secondary AIR valve
     
    Spark plug wires to the spark plugs
     
    HO 2 S sensor connection
     
    Fuel injector sight shield
     
    Negative battery cable
     

  2.  
  3. Run the engine and check for exhaust leaks.
  4.  

Right Side (Rear) Manifold-Models Without Nc8
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Fuel injector sight shield
     
    Air cleaner assembly
     
    Spark plug wires
     
    Brake booster heat shield
     
    Crossover pipe
     
    Engine harness from the right hand engine lift hook bracket
     
    Transaxle fluid dipstick and tube
     
    Oxygen (O 2 S) sensor
     
    Exhaust Gas Recirculation (EGR) feed pipe bolt from the manifold
     
    Transmission oil level tube and seal
     
    Exhaust manifold flange nuts
     
    Front exhaust pipe
     
    Engine lift bracket
     
    Exhaust manifold
     

  4.  

To install:

  1. Install or connect the following:

    Manifold to the cylinder head and crossover pipe using new gaskets
     
    Manifold mounting studs. Torque the studs and bolts to 22 ft. lbs. (30 Nm), beginning at the center and working outwards.
     
    Engine lift bracket
     
    Front exhaust pipe
     
    Front exhaust pipe-to-manifold nuts. Torque the nuts to 22 ft. lbs. (30 Nm).
     
    Transmission dipstick tube seal and the tube
     
    EGR feed pipe to the manifold
     
    O 2 S sensor
     
    Spark plug wires to the spark plugs
     
    Engine harness to the right hand engine lift hook bracket
     
    Crossover pipe
     
    Brake booster heat shield
     
    Air cleaner assembly
     
    Fuel injector sight shield
     
    Negative battery cable
     

  2.  
  3. Run the engine and check for exhaust leaks.
  4.  

4.6L Engine
Left W/O Rpo, Nc1 Or Nf7
  1. Remove the oxygen sensor and inspect the sensor for excessive deposits or damage.
  2.  
  3. Replace the oxygen sensor if necessary.
  4.  
  5. Remove the exhaust manifold to crossover pipe bolts.
  6.  
  7. Remove the exhaust manifold bolts.
  8.  
  9. Remove the exhaust manifold.
    NOTE
    DO NOT reuse the exhaust manifold to crossover pipe gasket.

  10.  
  11. Remove and discard the exhaust manifold to crossover pipe gasket.
    NOTE
    DO NOT reuse the exhaust manifold gasket.

  12.  
  13. Remove and discard the exhaust manifold gasket.
  14.  
  15. Disconnect the EGR inlet tube nut from the exhaust crossover.
    NOTE
    The EGR valve inlet pipe incorporates a crush seal connection at the water crossover. The EGR valve inlet pipe must be replaced if disconnected from the water crossover.

  16.  
  17. Remove the EGR inlet pipe bolt and flange from the water crossover.
  18.  
  19. Remove the EGR inlet tube and discard.
  20.  
  21. Remove the exhaust crossover stud and bolt.
  22.  
  23. Remove the exhaust crossover.
  24.  
  25. If equipped, remove the left coolant heater as follows:
    1. Remove the coolant heater bolt.
    2.  
    3. Remove the coolant heater from the cylinder block.
    4.  

  26.  

To install:

  1. If the engine is equipped with coolant heaters, install the left side heater as follows:
    1. Place the coolant heater in position on the cylinder block.
    2.  
    3. Install the coolant heater bolt. Tighten the coolant heater bolt to 80 inch lbs. (9 Nm).
    4.  

  2.  
  3. With the manifold still on the bench, position a new manifold gasket in place on the manifold sealing surface.
  4.  
  5. Install 2 outer manifold bolts in the manifold to retain the gasket.
  6.  
  7. Install a new manifold to intermediate pipe flange gasket.
  8.  
  9. Using 2 hands, place the manifold in the intermediate pipe and onto the cylinder head.
  10.  
  11. Install new manifold flange bolts for maximum joint integrity. Hand tighten. Do not torque the flange bolts to specification until the engine is mounted in the vehicle.
  12.  
  13. Hand tighten the 2 outer manifold bolts.
  14.  
  15. Install the remaining manifold bolts. Tighten the exhaust manifold bolts to 18 ft. lbs. (25 Nm).
  16.  
  17. Coat the oxygen sensor threads with high temperature anti-seize, (GM P/N 12377953) or equivalent.
  18.  
  19. Install the oxygen sensor. Tighten the oxygen sensor to 30 ft. lbs. (40 Nm).
  20.  

Left With Rpo Nc1 Or Nf7

NOTE
NC1 refers to vehicles with California Ultra Low Emission Vehicle package. NF7 refers to vehicles with Federal Emission package.

  1. Remove the A.I.R. valve pipe nuts from the exhaust manifold.
  2.  
  3. Remove the A.I.R. valve bolt from the mounting bracket.
  4.  
  5. Remove the A.I.R. valve nuts from the mounting bracket.
  6.  
  7. Remove the A.I.R. valve.
    NOTE
    DO NOT reuse the old A.I.R. valve pipe gasket.

  8.  
  9. Remove and discard the A.I.R. valve pipe gasket.
  10.  
  11. Remove the oxygen sensor and inspect the sensor for excessive deposits or damage.
  12.  
  13. Replace the oxygen sensor if necessary.
  14.  
  15. Remove the exhaust manifold to crossover pipe bolts.
  16.  
  17. Remove the exhaust manifold bolts.
  18.  
  19. Remove the exhaust manifold.
    NOTE
    DO NOT reuse the exhaust manifold to crossover pipe gasket.

  20.  
  21. Remove and discard the exhaust manifold to crossover pipe gasket.
    NOTE
    DO NOT reuse the exhaust manifold gasket.

  22.  
  23. Remove and discard the exhaust manifold gasket.
  24.  
  25. Disconnect the EGR inlet tube nut from the exhaust crossover.
    NOTE
    The EGR valve inlet pipe incorporates a crush seal connection at the water crossover. The EGR valve inlet pipe must be replaced if disconnected from the water crossover.

  26.  
  27. Remove the EGR inlet pipe bolt and flange from the water crossover.
  28.  
  29. Remove the EGR inlet tube and discard.
  30.  
  31. Remove the exhaust crossover stud and bolt.
  32.  
  33. Remove the exhaust crossover.
  34.  
  35. If equipped, remove the left coolant heater as follows:
  36.  
  37. Remove the coolant heater bolt.
  38.  
  39. Remove the coolant heater from the cylinder block.
  40.  

To install:

  1. If the engine is equipped with coolant heaters, install the left side heater as follows:
    1. Place the coolant heater in position on the cylinder block.
    2.  
    3. Install the coolant heater bolt. Tighten the coolant heater bolt to 89 inch lbs. (10 Nm).
      NOTE
      DO NOT reuse the exhaust manifold gasket.

    4.  

  2.  
  3. With the manifold still on the bench, position a new manifold gasket in place on the manifold sealing surface.
  4.  
  5. Install 2 outer manifold bolts in the manifold to retain the gasket.
  6.  
  7. Install a new manifold to intermediate pipe flange gasket.
  8.  
  9. Using 2 hands, place the manifold in the intermediate pipe and onto the cylinder head.
  10.  
  11. Install new manifold flange bolts for maximum joint integrity. Hand tighten. Do not torque the flange bolts to specification until the engine is mounted in the vehicle.
  12.  
  13. Hand tighten the 2 outer manifold bolts.
  14.  
  15. Install the remaining manifold bolts. Tighten the exhaust manifold bolts to 18 ft. lbs. (25 Nm).
  16.  
  17. Coat the oxygen sensor threads with high temperature anti-seize, GM P/N 12377953 or equivalent.
  18.  
  19. Install the oxygen sensor. Tighten the oxygen sensor to 30 ft. lbs. (40 Nm).
    NOTE
    DO NOT reuse the old A.I.R. valve pipe gasket.

  20.  
  21. Install the NEW A.I.R. valve pipe gasket.
  22.  
  23. Install the A.I.R. valve.
  24.  
  25. Install the A.I.R. valve nuts to the mounting bracket. Tighten the A.I.R. valve nuts to 80 inch lbs. (9 Nm).
  26.  
  27. Install the A.I.R. valve bolt through the mounting bracket. Tighten the A.I.R. valve bolt to 80 inch lbs. (9 Nm).
  28.  
  29. Install the A.I.R. valve pipe nuts to the exhaust manifold. Tighten the A.I.R. valve pipe nuts to 80 inch lbs. (9 Nm).
  30.  

Right W/O Rpo, Nc1 Or Nf7
  1. Remove the oxygen sensor and inspect the sensor for excessive deposits or damage.
  2.  
  3. Replace the oxygen sensor if necessary.
    NOTE
    The stud must be reinstalled in the original location. The stud may remain attached to the nut when initially removed during exhaust manifold removal. In order to prevent exhaust leakage between the exhaust manifold and cylinder head the nut and stud combination must be reinstalled during exhaust manifold installation in the original location.

  4.  
  5. Remove the right exhaust manifold retaining nuts.
    NOTE
    DO NOT reuse the exhaust manifold gasket.

  6.  
  7. Remove the exhaust manifold and the gasket.
  8.  
  9. If equipped, remove the right coolant heater as follows:
    1. Remove the coolant heater retaining bolt.
    2.  
    3. Remove coolant heater from the cylinder block.
    4.  

  10.  

To install:

  1. If the engine is equipped with coolant heaters, install the right side heater as follows:
    1. Place the coolant heater in position on the cylinder block.
    2.  
    3. Install the coolant heater bolt. Tighten the coolant heater bolt to 89 inch lbs. (10 Nm).
    4.  

  2.  
  3. Position a new manifold gasket in place on the cylinder head studs.
  4.  
  5. Using two hands, position the manifold onto the cylinder head.
  6.  
  7. Install two outer manifold nuts to hold the manifold in place.
  8.  
  9. Install the remaining manifold nuts. Tighten the exhaust manifold nuts to 18 ft. lbs. (25 Nm).
  10.  
  11. Coat the oxygen sensor threads with high temperature anti-seize, GM P/N 12377953 or equivalent.
  12.  
  13. Install the oxygen sensor. Tighten the oxygen sensor to 30 ft. lbs. (40 Nm).
  14.  
  15. Place the exhaust intermediate pipe in position.
  16.  
  17. Install the intermediate pipe stud at the cylinder head and the bolt at the lower crankcase. Tighten the intermediate pipe-to-lower crankcase bolt to 25 ft. lbs. (35 Nm). Tighten the intermediate pipe-to-cylinder head stud to 18 ft. lbs. (25 Nm).
    NOTE
    The EGR valve inlet pipe incorporates a crush seal connection at the water crossover. The EGR valve inlet pipe must be replaced if disconnected from the water crossover.

  18.  
  19. Hand start the NEW EGR inlet tube to intermediate pipe nut to prevent cross-threading. Tighten the EGR inlet tube-to-intermediate pipe nut to 44 ft. lbs. (60 Nm).
  20.  
  21. Connect the EGR inlet pipe flange to the water crossover.
  22.  
  23. Install the EGR inlet pipe to water crossover flange bolt. Tighten the EGR inlet tube to water crossover bolt to 18 ft. lbs. (25 Nm).
  24.  

Right With Rpo Nc1 Or Nf7
  1. Remove the A.I.R. valve pipe nuts from the exhaust manifold.
  2.  
  3. Remove the A.I.R. valve bolts from the mounting bracket.
  4.  
  5. Remove the A.I.R. valve.
    NOTE
    DO NOT reuse the A.I.R. valve pipe gasket.

  6.  
  7. Remove and discard the A.I.R. valve pipe gasket.
  8.  
  9. Remove the oxygen sensor and inspect the sensor for excessive deposits or damage.
  10.  
  11. Replace the oxygen sensor if necessary.
    NOTE
    The stud must be reinstalled in the original location. The stud may remain attached to the nut when initially removed during exhaust manifold removal. In order to prevent exhaust leakage between the exhaust manifold and cylinder head the nut and stud combination must be reinstalled during exhaust manifold installation in the original location.

  12.  
  13. Remove the right exhaust manifold retaining nuts.
    NOTE
    DO NOT reuse the exhaust manifold gasket.

  14.  
  15. Remove the exhaust manifold and the gasket.
  16.  
  17. If equipped, remove the right coolant heater as follows:
  18.  
  19. Remove the coolant heater retaining bolt.
  20.  
  21. Remove coolant heater from the cylinder block.
  22.  

To install:

  1. If the engine is equipped with coolant heaters, install the right side heater as follows:
    1. Place the coolant heater in position on the cylinder block.
    2.  
    3. Install the coolant heater bolt. Tighten the coolant heater bolt to 89 inch lbs. (10 Nm).
    4.  

  2.  
  3. Position a new manifold gasket in place on the cylinder head studs.
  4.  
  5. Using two hands, position the manifold onto the cylinder head.
  6.  
  7. Install two outer manifold nuts to hold the manifold in place.
  8.  
  9. Install the remaining manifold nuts. Tighten the exhaust manifold nuts to 18 ft. lbs. (25 Nm).
  10.  
  11. Coat the oxygen sensor threads with high temperature anti-seize, GM P/N 12377953 or equivalent.
  12.  
  13. Install the oxygen sensor. Tighten the oxygen sensor to 30 ft. lbs. (40 Nm).
    NOTE
    DO NOT reuse the old A.I.R. valve pipe gasket.

  14.  
  15. Install the NEW A.I.R. valve pipe gasket.
  16.  
  17. Install the A.I.R. valve.
  18.  
  19. Install the A.I.R. valve bolts through the mounting bracket. Tighten the A.I.R. valve bolts to 80 inch lbs. (9 Nm).
  20.  
  21. Install the A.I.R. valve pipe nuts to the exhaust manifold. Tighten the A.I.R. valve pipe nuts to 80 inch lbs. (9 Nm).
  22.  
  23. Place the exhaust intermediate pipe in position.
  24.  
  25. Install the intermediate pipe stud at the cylinder head and the bolt at the lower crankcase. Tighten the intermediate pipe-to-lower crankcase bolt to 18 ft. lbs. (25 Nm).. Tighten the intermediate pipe-to-cylinder head stud to 18 ft. lbs. (25 Nm).
    NOTE
    The EGR valve inlet pipe incorporates a crush seal connection at the water crossover. The EGR valve inlet pipe must be replaced if disconnected from the water crossover.

  26.  
  27. Hand start the NEW EGR inlet tube to intermediate pipe nut to prevent cross-threading. Tighten the EGR inlet tube-to-intermediate pipe nut to 44 ft. lbs. (60 Nm).
  28.  
  29. Connect the EGR inlet pipe flange to the water crossover.
  30.  
  31. Install the EGR inlet pipe to water crossover flange bolt. Tighten the EGR inlet tube to water crossover bolt to 18 ft. lbs. (25 Nm).
  32.  

 
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