GM Bonneville/Eighty Eight/LeSabre 1986-1999

Exhaust Manifold

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REMOVAL & INSTALLATION



3.8L (VIN 3) Engine

See Figures 1 and 2

  1. Disconnect the negative battery cable.
  2.  

Failure to disconnect the intermediate shaft from the rack and pinion stub shaft may result in damage to the steering gear and/or intermediate shaft.

  1. Remove the pinch bolt from the intermediate shaft and separate the intermediate shaft from the stub shaft.
  2.  
  3. Raise and safely support the vehicle.
  4.  
  5. Remove the 2 bolts attaching the exhaust pipe to the manifold.
  6.  
  7. Carefully lower the vehicle.
  8.  
  9. Remove the upper engine support strut.
  10.  
  11. Place a jack under the front crossmember of the cradle and raise the jack until it starts to raise the vehicle.
  12.  
  13. Remove the 2 front body mount bolts.
  14.  
  15. With the cushions removed, thread the body mount bolts and retainers a minimum of 3 turns into the cage nuts.
  16.  
  17. Release the jack slowly.
  18.  

To avoid damage, do not lower the cradle without it being restrained.

  1. Remove the power steering pump and bracket from the cylinder head and exhaust manifold.
  2.  
  3. Disconnect the oxygen sensor.
  4.  
  5. If removing the left side exhaust manifold, remove the upper engine support strut.
  6.  
  7. Remove the 2 nuts retaining the crossover pipe to the exhaust manifold.
  8.  
  9. Remove the 6 bolts attaching the manifold to the cylinder head.
  10.  
  11. Remove the exhaust manifold. Carefully, clean the gasket sealing surfaces of old gasket material.
  12.  



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Fig. Fig. 1: Right exhaust manifold mounting



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Fig. Fig. 2: Left exhaust manifold mounting

To install:
  1. Install the exhaust manifold and the manifold-to-cylinder head bolts. Tighten to 37 ft. lbs. (50 Nm).
  2.  
  3. If the left side exhaust manifold was removed, install the crossover pipe to the manifold.
  4.  
  5. If the right side exhaust manifold was removed, install the upper engine support strut.
  6.  
  7. Connect the oxygen sensor wire.
  8.  
  9. Install the power steering pump and bracket.
  10.  
  11. Support the cradle with the jack. Remove the 2 body mount bolts and install the cushions.
  12.  
  13. Raise the cradle into position and install the 2 body mount bolts.
  14.  
  15. Remove the jack.
  16.  
  17. Connect the intermediate shaft to the stub shaft and install the pinch bolt.
  18.  
  19. Raise and safely support the vehicle.
  20.  
  21. Install the exhaust pipe-to-manifold bolts.
  22.  
  23. Carefully lower the vehicle.
  24.  
  25. Connect the negative battery cable.
  26.  

3.8L (VIN C and L) Engine

RIGHT SIDE (REAR)

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. If necessary, disconnect the Mass Air Flow (MAF) sensor, air intake duct, the crankcase ventilation pipe and the IAC connector from the throttle body.
  4.  
  5. Label and disconnect the wires from the spark plugs. Disconnect the oxygen sensor lead.
  6.  
  7. For vehicles through 1992, remove the EGR pipe.
  8.  
  9. Unfasten the two bolts attaching the right exhaust manifold to the left exhaust manifold.
  10.  
  11. Remove the plastic vacuum tank mounted on the cowl.
  12.  
  13. Raise and safely support the vehicle.
  14.  
  15. Remove the catalytic converter heat shield and pipe hanger.
  16.  
  17. Unfasten the front exhaust pipe-to-exhaust manifold attaching nuts.
  18.  
  19. Separate the front exhaust pipe from the exhaust manifold.
  20.  
  21. Carefully lower the vehicle.
  22.  
  23. Remove the engine lift bracket.
  24.  
  25. Unfasten the exhaust manifold nuts/studs, then remove the manifold from the vehicle. If equipped, remove and discard the gasket. Thoroughly clean the gasket mating surfaces.
  26.  

To install:
  1. Install the exhaust manifold and secure with the nuts/studs previously removed. Tighten the exhaust manifold retainers to 38-41 ft. lbs. (51-56 Nm).
  2.  
  3. Install the engine lift bracket.
  4.  
  5. Raise and safely support the vehicle.
  6.  
  7. Attach the front exhaust pipe to the exhaust manifold and secure with the retaining nuts.
  8.  
  9. Install the catalytic converter heat shield and pipe hanger.
  10.  
  11. Carefully lower the vehicle.
  12.  
  13. Install the plastic vacuum tank, mounted on the cowl.
  14.  
  15. Install the two bolts attaching the right exhaust manifold to the left exhaust manifold. Tighten the bolts to 15 ft. lbs. (20 Nm).
  16.  
  17. Connect the oxygen sensor lead.
  18.  
  19. If removed, install the EGR pipe.
  20.  
  21. Install the transaxle oil level indicator and indicator tube.
  22.  
  23. Install the crossover pipe heat shield.
  24.  
  25. Install the throttle cable bracket.
  26.  
  27. Connect the spark plug wires, as tagged during removal.
  28.  
  29. If removed, connect the Mass Air Flow sensor, air intake duct, the crankcase ventilation pipe and the IAC connector from the throttle body.
  30.  
  31. Connect the negative battery cable. Start the engine and check for leaks.
  32.  

LEFT SIDE (FRONT)

See Figures 2 through 12

  1. Disconnect the negative battery cable.
  2.  



Click image to see an enlarged view

Fig. Fig. 3: The exhaust manifold is mounted on studs and secured with retaining nuts

  1. If necessary, remove the Mass Air Flow (MAF) sensor, air intake duct and crankcase ventilation pipe.
  2.  
  3. Remove any necessary brackets.
  4.  



Click image to see an enlarged view

Fig. Fig. 4: Remove any brackets that will interfere with exhaust manifold removal

  1. Remove the exhaust crossover pipe-to-exhaust manifold bolts, attaching the left and right exhaust manifolds.
  2.  



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Fig. Fig. 5: Remove the exhaust crossover pipe-to-manifold retainers ...



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Fig. Fig. 6: ... then remove the retaining nut and stud assemblies



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Fig. Fig. 7: You may have to lift the collar up to access the other crossover pipe retainer



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Fig. Fig. 8: Once the collar is moved aside, you can remove the other nut and stud retainer

  1. Label and disconnect the spark plug wires.
  2.  
  3. Remove the exhaust manifold-to-cylinder head bolts/studs and the manifold. It may be necessary for additional clearance, to remove the oil dipstick tube, before removing the manifold..
  4.  



Click image to see an enlarged view

Fig. Fig. 9: It may be necessary to remove the oil dipstick tube. Do so by pulling it straight out of the block



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Fig. Fig. 10: After all of the retainers are removed, you can remove the exhaust manifold from the engine



Click image to see an enlarged view

Fig. Fig. 11: You can use a piece of Scotchbrite® or equivalent non-abrasive scouring pad to clean the gasket mating surfaces



Click image to see an enlarged view

Fig. Fig. 12: Make sure to also clean the engine block mating surfaces

  1. Clean the gasket mounting surfaces and install a new gasket.
  2.  

To install:
  1. Install the exhaust manifold and tighten the manifold mounting bolts/studs to 37-41 ft. lbs. (50-56 Nm).
  2.  
  3. If removed, install the oil dipstick tube.
  4.  
  5. Connect the spark plug wires. Install the exhaust crossover pipe-to-exhaust manifold bolts.
  6.  
  7. If removed, install the MAF sensor, air intake duct and crankcase ventilation pipe.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Start the engine and check for exhaust leaks.
  12.  

1992 3.8L (VIN 1) Engine

RIGHT SIDE
  1. Disconnect the negative battery cable.
  2.  
  3. If necessary, disconnect the Mass Air Flow (MAF) sensor, air intake duct, the crankcase ventilation pipe and the IAC connector from the throttle body.
  4.  
  5. Label and disconnect the wires from the spark plugs. Disconnect the oxygen sensor lead.
  6.  
  7. If equipped, disconnect the heater inlet pipe from the manifold stud. If equipped, remove the transaxle oil indicator tube.
  8.  
  9. Remove the exhaust crossover pipe-to-exhaust manifold bolts and the pipe. Disconnect the alternator bracket, if necessary.
  10.  
  11. Raise and support the vehicle safely. Remove the exhaust pipe-to-manifold bolts, the exhaust manifold-to-cylinder head bolts and the manifold.
  12.  
  13. Remove the EGR pipe from the exhaust manifold.
  14.  
  15. Clean the gasket mounting surfaces.
  16.  

To install:
  1. Replace the EGR pipe to the exhaust manifold.
  2.  
  3. Install the exhaust manifold, using a new gasket. Tighten the mounting studs to 37-41 ft. lbs. (50-56 Nm).
  4.  
  5. Lower the vehicle. Connect the alternator bracket, if necessary.
  6.  
  7. Install the crossover pipe and replace the exhaust manifold-to-cylinder bolts.
  8.  
  9. If equipped, replace the transaxle oil indicator tube. Connect the heater inlet pipe to the manifold, if equipped.
  10.  
  11. Connect the oxygen sensor lead and the spark plug wires.
  12.  
  13. If removed, connect the Mass Air Flow sensor, air intake duct, the crankcase ventilation pipe and the IAC connector from the throttle body.
  14.  
  15. Connect the negative battery cable. Start the engine and check for leaks.
  16.  

LEFT SIDE

See Figure 13

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the 2 flange bolts and the manifold-to-bracket nut.
  4.  
  5. Remove the manifold to engine studs and remove the manifold.
  6.  



Click image to see an enlarged view

Fig. Fig. 13: Exploded view of the left side exhaust manifold on a 1992 supercharged engine

To install:
  1. Clean the gasket mounting surfaces and install a new gasket.
  2.  
  3. Install the exhaust manifold and tighten the manifold mounting studs to 37-41 ft. lbs. (50-56 Nm).
  4.  
  5. Install the manifold to bracket nut and the flange gasket. Install the flange bolts.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Start the engine and check for exhaust leaks.
  10.  

1993-99 3.8L (VIN 1 and K) Engine

right side (rear)

See Figures 14 and 15

  1. Disconnect the negative battery cable.
  2.  
  3. Tag and disconnect the spark plug wires from the spark plugs.
  4.  
  5. If equipped with a supercharged engine, remove the throttle cable bracket. Remove the crossover pipe heat shield.
  6.  
  7. Remove the transaxle oil level indicator and indicator tube.
  8.  
  9. Detach the oxygen sensor lead.
  10.  
  11. Unfasten the two bolts attaching the right exhaust manifold to the crossover pipe or left exhaust manifold, as applicable.
  12.  
  13. Remove the vacuum reservoir, mounted on the cowl.
  14.  
  15. Raise and safely support the vehicle.
  16.  
  17. Remove the front exhaust pipe-to-exhaust manifold attaching nuts.
  18.  
  19. Separate the front exhaust pipe from the exhaust manifold.
  20.  
  21. Carefully lower the vehicle.
  22.  
  23. Remove the engine lift bracket.
  24.  



Click image to see an enlarged view

Fig. Fig. 14: Remove the engine lift bracket - 1993-99 VIN 1 and K engines

  1. Unfasten the exhaust manifold studs, then remove the manifold from the vehicle.
  2.  
  3. Remove and discard the gasket, then thoroughly clean the gasket mating surfaces.
  4.  



Click image to see an enlarged view

Fig. Fig. 15: Exploded view of the right side manifold, gasket and retaining studs - 1993-99 VIN 1 and K engines

To install:
  1. Install a new gasket, then position the exhaust manifold. Secure with the retaining studs and tighten to 38 ft. lbs. (51 Nm) for 1993-95 vehicles or to 2 ft. lbs. (30 Nm) for 1996-99 vehicles.
  2.  
  3. Install the engine lift bracket.
  4.  
  5. Raise and safely support the vehicle.
  6.  
  7. Attach the front exhaust pipe to the manifold.
  8.  
  9. Carefully lower the vehicle.
  10.  
  11. Install the vacuum reservoir, mounted on the cowl.
  12.  
  13. Install the two bolts attaching the right exhaust manifold to the left manifold or crossover pipe, as applicable. Tighten the bolts to 15 ft. lbs. (20 Nm).
  14.  
  15. Attach the oxygen sensor lead.
  16.  
  17. Install the transaxle oil level indicator and indicator tube.
  18.  
  19. For supercharged engines, install the crossover pipe heat shield and the throttle cable bracket.
  20.  
  21. Attach the spark plug wires to the spark plugs, as tagged during removal.
  22.  
  23. Connect the negative battery cable.
  24.  

left side (front)

See Figure 16

  1. Disconnect the negative battery cable.
  2.  
  3. Unfasten the two bolts attaching the left exhaust manifold to the crossover pipe or right exhaust manifold, as applicable.
  4.  
  5. Tag and disconnect the spark plug wires from the spark plugs.
  6.  
  7. Remove the oil level indicator and tube.
  8.  
  9. Remove the manifold studs and bolts, then remove the manifold from the vehicle. Remove and discard the gasket and thoroughly clean the gasket mating surfaces.
  10.  



Click image to see an enlarged view

Fig. Fig. 16: Left exhaust manifold attachment - 1993-99 VIN 1 and K engines

To install:
  1. Install a new gasket, then position the exhaust manifold.
  2.  
  3. Install the oil level indicator tube and indicator.
  4.  
  5. Install the manifold studs and bolts. Tighten to 38 ft. lbs. (51 Nm) for 1993-95 vehicles or to 2 ft. lbs. (30 Nm) for 1996-99 vehicles.
  6.  
  7. Connect the spark plug wires to the plugs, as tagged during removal.
  8.  
  9. Install the two bolts attaching the left exhaust manifold to the right exhaust manifold or crossover pipe, as applicable. Tighten the bolts to 15 ft. lbs. (20 Nm).
  10.  
  11. Connect the negative battery cable.
  12.  

 
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