GM Bonneville/Eighty Eight/LeSabre 1986-1999

Cylinder Head

Print

REMOVAL & INSTALLATION



3.8L (VIN 3) Engine

See Figure 1

  1. Properly relieve the fuel system pressure, as outlined in Fuel System .
  2.  
  3. Disconnect the negative battery cable. Raise and safely support the vehicle.
  4.  
  5. Drain the engine coolant from the radiator and cylinder block, then carefully lower the vehicle.
  6.  
  7. Remove the serpentine belt, as outlined in General Information & Maintenance .
  8.  
  9. Remove the alternator, AIR pump, oil indicator and power steering pump, as required. Position to the side.
  10.  
  11. Remove the throttle cable. Remove the cruise control cable, if equipped.
  12.  
  13. Disconnect the fuel lines and remove the fuel rail.
  14.  
  15. Remove the heater hoses and radiator hoses.
  16.  
  17. Tag and disconnect all vacuum and electrical wiring.
  18.  
  19. Remove the radiator and cooling fan, if necessary.
  20.  
  21. Remove the intake manifold and valve cover.
  22.  
  23. Remove the exhaust manifold(s).
  24.  
  25. Remove the rocker arm assembly and pushrods.
  26.  
  27. Unfasten the cylinder head bolts and remove the cylinder head. Remove and discard the cylinder head gasket.
  28.  
  29. Clean the cylinder head and block from any foreign matter, nicks or heavy scratches. Clean the cylinder head bolt threads and threads in the cylinder block. The cylinder head must be inspected before installation. Refer to the Engine Reconditioning portion of this section for details.
  30.  

To install:
  1. Position a new cylinder head gasket on the block.
  2.  
  3. Carefully guide the cylinder head into place. Coat the cylinder head bolts with a suitable sealing compound and install them.
  4.  
  5. Tighten the cylinder head bolts according to the following procedure:
    1. Tighten the cylinder head bolts in sequence to 25 ft. lbs. (34 Nm).
    2.  
    3. Do not exceed 60 ft. lbs. (81 Nm) at any point during the next 2 steps.
    4.  
    5. Using a torque angle gauge, tighten each bolt an additional 90° in sequence.
    6.  
    7. Tighten each bolt an additional 90° in sequence.

      Click image to see an enlarged view

      Fig. Fig. 1: Cylinder head bolt tightening sequence - 3.8L (VIN 3) engine

    8.  

  6.  
  7. Install the exhaust manifold(s).
  8.  
  9. Install the intake manifold, pushrods and rocker arm assembly.
  10.  
  11. Install the valve cover.
  12.  
  13. Install the radiator and cooling fan, as required.
  14.  
  15. Connect all vacuum and electrical wiring.
  16.  
  17. Install the heater hoses and radiator hoses.
  18.  
  19. Connect the fuel lines and fuel rail.
  20.  
  21. Install the throttle cable. Install the cruise control cable, if equipped.
  22.  
  23. Install the alternator, AIR pump, oil indicator and power steering pump.
  24.  
  25. Install the serpentine belt.
  26.  
  27. Connect the negative battery cable.
  28.  
  29. Fill cooling system and check for leaks. Start the engine and allow to come to normal operating temperature. Check for leaks and top off the coolant.
  30.  

3.8L (VIN C, L, 1 and K) Engine

See Figures 2 through 17

  1. Properly relieve the fuel system pressure, as outlined in Fuel System of this repair guide.
  2.  
  3. Remove the intake manifold, as outlined earlier in this section.
  4.  
  5. Remove either the right or left exhaust manifold, depending upon which cylinder head you are removing.
  6.  
  7. Remove the applicable valve cover for the cylinder head you are removing.
  8.  
  9. If you are removing the left (front) cylinder head, perform the following:
    1. Remove the ignition coil assembly.
    2.  
    3. Tag and disconnect the spark plug wires.
    4.  
    5. Remove the alternator and the alternator bracket.
    6.  
    7. Unfasten the A/C compressor bracket bolt.
    8.  

  10.  
  11. If removing the right (rear) cylinder head, perform the following:
    1. Unbolt the power steering pump and position aside. Do NOT disconnect the fluid lines.
    2.  
    3. Remove the accessory drive belt tensioner assembly.
    4.  
    5. Remove the fuel line heat shield.
    6.  

  12.  
  13. Remove the rocker arm assemblies, guide plate and pushrods
  14.  
  15. If necessary, you can remove the lifter guide plate retainer, the plate, lifter guide and the lifters.
  16.  



Click image to see an enlarged view

Fig. Fig. 2: Unfasten the retainers, then remove the rocker arms



Click image to see an enlarged view

Fig. Fig. 3: Remove the pushrod guide plate ...



Click image to see an enlarged view

Fig. Fig. 4: ... then remove the pushrods



Click image to see an enlarged view

Fig. Fig. 5: Unfasten the lifter guide plate retaining bolt, then remove the plate



Click image to see an enlarged view

Fig. Fig. 6: Remove the lifter guide by lifting it off ...



Click image to see an enlarged view

Fig. Fig. 7: ... then remove the lifter from its bore

  1. Unfasten the cylinder head retaining bolts, then remove the head from the engine. Remove and discard the cylinder head gasket. On 1996-99 vehicles, discard the cylinder head bolts and replace with new ones, of the same type, for installation.
  2.  



Click image to see an enlarged view

Fig. Fig. 8: Most cylinder heads have 8 mounting bolts (see arrows)



Click image to see an enlarged view

Fig. Fig. 9: Depending upon application, remove the head bolts and inspect them for reuse, or discard them



Click image to see an enlarged view

Fig. Fig. 10: After removing the bolts, carefully lift the cylinder head from the engine block, and remove it from the vehicle

The cylinder bolt hold threads can be cleaned using a7/16-4 tap.

  1. Clean the cylinder head and block from any foreign matter, nicks or heavy scratches. Clean the cylinder head bolt threads and threads in the cylinder block. The cylinder head must be inspected before installation. Refer to the Engine Reconditioning portion of this section for details.
  2.  



Click image to see an enlarged view

Fig. Fig. 11: If necessary, you can remove the gasket from the cylinder head after it is removed from the vehicle



Click image to see an enlarged view

Fig. Fig. 12: Use a suitable gasket scraper to remove the old gasket material from the cylinder head



Click image to see an enlarged view

Fig. Fig. 13: After shielding the cylinder bores from debris, also be sure to thoroughly clean the engine block mating surfaces



Click image to see an enlarged view

Fig. Fig. 14: Exploded view of the cylinder head and related components - 3.8L (VIN L) engine shown

To install:

WARNING
Head gaskets are not interchangeable. Not installing the gasket with the arrow pointing to the front will cause gasket failure and, possibly, engine failure.

  1. Place the cylinder head gasket on the engine block dowels with the note THIS SIDE UP facing the cylinder head and the arrow facing the front of the engine.
  2.  
  3. Place the cylinder head in position, on top of the new gasket.
  4.  



Click image to see an enlarged view

Fig. Fig. 15: After installing a new gasket, position the cylinder head on top of the gasket

On 1996-99 vehicles, the head bolts are designed to permanently stretch when tightened. the correct part number fastener MUST be used when replacing this type of bolt. Never use a bolt which is stronger in this application. If the correct bolt is not used, the parts will not be tightened correctly and component or system damage may occur.

  1. Apply a suitable thread sealer to the cylinder head bolts on 1988-95 vehicles, or get new cylinder head bolts on 1996-99 vehicles, install them and tighten as follows:
    1. Tighten the cylinder head bolts, in the sequence shown in the accompanying figure, to 35-37 ft. lbs. (47-50 Nm).
    2.  
    3. Rotate each bolt 130°, in sequence, using a torque angle meter.
    4.  
    5. Rotate the center 4 bolts an additional 30°, in sequence, using a torque angle meter.

      Click image to see an enlarged view

      Fig. Fig. 16: Cylinder head bolts MUST be tightened in this sequence - 3.8L engines, except VINs 3 and B



      Click image to see an enlarged view

      Fig. Fig. 17: ALWAYS use a reliable torque wrench when tightening the cylinder head bolts!

    6.  

  2.  
  3. If removed, install the lifters, guide, plate and retainer.
  4.  
  5. Install the pushrods, guide plate and rocker arm assemblies. Apply a suitable compound to the rocker arm pedestal bolts before assembly and tighten the bolts as follows:
    1. 1988-92 vehicles: 28 ft. lbs. (38 Nm).
    2.  
    3. 1993-94 vehicles: 19 ft. lbs. (25 Nm), plus an additional 70° rotation.
    4.  
    5. 1995-96 vehicles: 11 ft. lbs. (15 Nm), plus additional 90° rotation.
    6.  

  6.  
  7. Install the intake manifold.
  8.  
  9. Install the valve cover.
  10.  
  11. Install the exhaust manifold.
  12.  
  13. If installing the left (front) cylinder head, proceed as follows:
    1. Install the A/C compressor bracket bolt and tighten to 52 ft. lbs. (70 Nm).
    2.  
    3. Install the alternator support bracket on the cylinder head.
    4.  
    5. Install the alternator.
    6.  
    7. Install the ignition coil pack and connect the spark plug wires as tagged during removal.
    8.  

  14.  
  15. If installing the right (rear) cylinder head, perform the following:
    1. Install the belt tensioner assembly.
    2.  
    3. Install the power steering pump.
    4.  
    5. Install the fuel line heat shield.
    6.  

  16.  
  17. Connect the negative battery cable.
  18.  
  19. Fill cooling system and check for leaks. Start the engine and allow it to come to normal operating temperature. Check for leaks and top off the coolant.
  20.  

 
label.common.footer.alt.autozoneLogo