GM Bonneville/Eighty Eight/LeSabre 1986-1999

Timing Chain Cover

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REMOVAL & INSTALLATION



3.8L (VIN 3) Engine
  1. Properly relieve the fuel system pressure.
  2.  
  3. If not already done, disconnect the negative battery cable.
  4.  
  5. Drain the cooling system into a suitable container.
  6.  
  7. Disconnect the lower radiator hose and the heater hose from the water pump.
  8.  
  9. Remove the 2 nuts from the front engine mount from the cradle, then carefully raise the engine using a suitable lifting device.
  10.  
  11. Remove the water pump pulley and the serpentine belt.
  12.  
  13. Remove the alternator and brackets.
  14.  
  15. Remove the balancer bolt and washer. Using a puller, remove the balancer.
  16.  
  17. Remove the cover-to-block bolts. Remove the 2 oil pan-to-cover bolts.
  18.  
  19. Remove the cover and gasket. Thoroughly clean the mating surfaces of the front cover and cylinder block.
  20.  
  21. After removing the timing cover, pry oil seal from front of cover. Lubricate the seal lip and install new lip seal with lip, open side of seal, facing toward the cylinder block. Carefully drive or press seal into place.
  22.  

To install:

Remove the oil pump cover and pack the space around the oil pump gears completely with petroleum jelly. There must be no air space left inside the pump. If the pump is not packed, it may not begin to pump oil as soon as the engine is started and engine damage may result.

  1. Install a new gasket to the oil pan and cylinder block. Install the front cover. Apply sealer to the threads of the cover retaining bolts and secure the cover.
  2.  
  3. Install the cover-to-block bolts and the 2 oil pan-to-cover bolts.
  4.  
  5. Install the balancer, washer and balancer bolt.
  6.  
  7. Install the alternator brackets and install the alternator.
  8.  
  9. Install the water pump pulley and the serpentine belt.
  10.  
  11. Lower the engine into position and install the 2 nuts to the front engine mount at the cradle.
  12.  
  13. Connect the lower radiator hose and the heater hose to the water pump.
  14.  
  15. Connect the negative battery cable.
  16.  
  17. 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.
  18.  

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

1988-90 VEHICLES

See Figures 1 through 8

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the coolant into a clean container for reuse.
  4.  
  5. Remove the serpentine drive belt.
  6.  
  7. Disconnect the heater pipes. Disconnect the lower radiator and bypass hoses from the front cover.
  8.  
  9. Raise and safely support the vehicle.
  10.  
  11. Remove the right front tire and wheel assembly, then remove the inner splash shield.
  12.  



Click image to see an enlarged view

Fig. Fig. 1: Remove the inner splash shield retaining clips, then remove the shield

  1. Unfasten the retaining bolt, then remove the crankshaft balancer.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Unfasten the crankshaft balancer retaining bolt ...



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Fig. Fig. 3: ... then remove the crankshaft balancer. Note the teeth on the back of the balancer

  1. Tag and unplug the electrical connections from the camshaft sensor, crankshaft sensor and the oil pressure switch.
  2.  



Click image to see an enlarged view

Fig. Fig. 4: Unplug the electrical connector (1) from the crankshaft position sensor (2)

  1. If necessary, remove the oil filter.
  2.  
  3. Unfasten the oil pan-to-front cover bolts.
  4.  



Click image to see an enlarged view

Fig. Fig. 5: Unfasten the oil pan-to-front cover retaining bolts

  1. Remove the front cover mounting bolts, then remove the front cover assembly. Remove and discard the gasket.
  2.  



Click image to see an enlarged view

Fig. Fig. 6: After removing the remaining front cover bolts, remove the cover from the engine

  1. If necessary, you can replace the front cover oil seal at this time by carefully prying it from the cover. You can also remove the seal with the cover installed. For details, refer to the procedure located later in this section.
  2.  
  3. Thoroughly clean the gasket surfaces on the cover and the cylinder block.
  4.  



Click image to see an enlarged view

Fig. Fig. 7: Exploded view of the front cover, gasket and oil seal - 1990 3.8L (VIN C) engine shown

To install:
  1. If the front cover seal was removed, lubricate the seal lip and install new lip seal with lip, open side of seal, facing toward the cylinder block. Carefully drive or press the seal into place.
  2.  
  3. Position a new gasket on the cylinder block.
  4.  
  5. Apply a suitable sealant to the bolt threads, then install the front cover, and tighten the mounting bolts to 22 ft. lbs. (30 Nm).
  6.  
  7. Replace the oil pan-to-cover mounting bolts and tighten to 88 inch lbs. (10 Nm) .
  8.  
  9. If removed, install a new oil filter.
  10.  
  11. Attach the electrical connections to the oil pressure switch, crankshaft position sensor and camshaft position sensor. Adjust the crankshaft position sensor using a suitable tool.
  12.  



Click image to see an enlarged view

Fig. Fig. 8: There is a specific tool available for adjusting the crankshaft position sensor

  1. Install the crankshaft balancer and retaining bolt, then tighten the bolt to 219 ft. lbs. (298 Nm).
  2.  
  3. Install the inner fender splash shield and the right front tire and wheel assembly.
  4.  
  5. Carefully lower the vehicle.
  6.  
  7. Connect the coolant bypass hose and radiator hoses to the front cover. Connect the heater pipes.
  8.  
  9. Install the drive belt.
  10.  
  11. Refill the cooling system and connect the negative battery cable.
  12.  
  13. Start the engine and check for leaks. Check the coolant level and add, if necessary.
  14.  

1991-99 VEHICLES

See Figures 9, 10 and 11

  1. Disconnect the negative battery cable.
  2.  
  3. For 1992-99 vehicles, remove the torque axis mount, as follows:
    1. Use a suitable engine support fixture and lifting bracket to raise the engine slightly to take the weight off of the engine mounts.
    2.  
    3. Remove the through-bolt from the torque axis (front) engine mount.
    4.  
    5. Lift the engine with the support fixture until the power steering reservoir touches the strut tower cross brace.
    6.  
    7. Loosen the bottom two bolts on the torque axis (front) engine mount.
    8.  
    9. Remove the A/C line clip and top two bolts on the torque axis engine mount, then remove the mount.
    10.  
    11. Remove the 2 bolts and nut attaching the engine torque axis mount bracket assembly to the front of the engine.
    12.  

  4.  
  5. For 1996-99 vehicles, remove the torque axis mount bracket.
  6.  
  7. Remove the serpentine drive belt.
  8.  
  9. For the 1995 VIN K engine and 1996-99 VIN 1 engines, remove the drive belt idler pulley and bracket.
  10.  
  11. Remove the crankshaft pulley/damper using a suitable puller, as outlined earlier in this section.
  12.  
  13. Remove the sensor shield, then remove the crankshaft position sensor.
  14.  



Click image to see an enlarged view

Fig. Fig. 9: Remove the crankshaft position sensor shield

  1. Remove the oil pan-to-front cover bolts.
  2.  
  3. Remove the front cover attaching bolts, then remove the cover. Remove and discard the front cover gasket.
  4.  
  5. If necessary, you can replace the front cover oil seal at this time by carefully prying it from the cover. You can also remove the seal with the cover installed. For details, refer to the procedure located later in this section.
  6.  
  7. Thoroughly clean the gasket surfaces on the cover and the cylinder block. If the oil pan gasket is very swollen, you must remove the oil pan and replace the gasket.
  8.  



Click image to see an enlarged view

Fig. Fig. 10: Exploded view of the timing chain, front cover and related components

  1. Inspect the timing chain for overall "in and out" movement. It should not exceed 1 in. (25mm).
  2.  

To install:
  1. If the front cover seal was removed, lubricate the seal lip and install new lip seal with lip, open side of seal, facing toward the cylinder block. Carefully drive or press the seal into place.
  2.  
  3. Position a new front cover gasket on the cylinder block.
  4.  



Click image to see an enlarged view

Fig. Fig. 11: Position a new front cover gasket on the cylinder block

  1. Apply a suitable sealant to the bolt threads, then install the front cover and the attaching bolts. Tighten the bolts to 22 ft. lbs. (30 Nm) for 1991-95 vehicles. For 1996-99 vehicles, tighten the bolts to 11 ft. lbs. (15 Nm), plus an additional 40° rotation with a torque angle meter.
  2.  
  3. Install the oil pan-to-front cover bolts and tighten to 124 inch lbs. (14 Nm).
  4.  
  5. Install the belt tensioner assembly.
  6.  
  7. For the 1995 VIN K and 1996-99 VIN 1 engines, install the drive belt idler pulley and bracket.
  8.  
  9. For 1992 vehicles, adjust the crankshaft position sensor using tool J37087 or equivalent.
  10.  
  11. Install the crankshaft position sensor, then install the sensor shield.
  12.  
  13. Install the crankshaft damper/pulley and the bolt. Tighten the bolt to the specifications given earlier in this section.
  14.  
  15. Install the drive belt.
  16.  
  17. If removed, install the torque axis mount, as follows:
    1. Attach the torque axis engine mount bracket assembly to the front of the engine using the 2 bolts and nut.
    2.  
    3. Replace the 2 upper bolts previously removed from the torque axis engine mount, and attach the mount and plastic clip for the A/C lines.
    4.  
    5. Tighten the 2 lower bolts that were previously loosened on the torque axis engine mount.
    6.  
    7. Adjust the engine height to align the torque mount with the torque axis mount bracket.
    8.  
    9. Insert the through-bolt, then attach and tighten the retaining nut. Remove the engine support and lifting fixture.
    10.  

  18.  
  19. Connect the negative battery cable.
  20.  

 
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