GM Bonneville/Eighty Eight/LeSabre 1986-1999

Timing Chain and Sprockets

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REMOVAL & INSTALLATION



3.8L (VIN 3) Engine

See Figures 1 and 2

  1. Properly relieve the fuel system pressure.
  2.  
  3. If not already done, disconnect the negative battery cable.
  4.  
  5. Remove the timing chain front cover, as outlined earlier in this section.
  6.  
  7. Turn the crankshaft so the timing marks are aligned.
  8.  



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Fig. Fig. 1: The timing marks MUST be aligned before removing the timing chain

  1. Remove the crankshaft oil slinger, as required.
  2.  
  3. Remove the camshaft sprocket bolts.
  4.  
  5. Remove the camshaft sensor magnet assembly.
  6.  
  7. Use 2 prybars to alternately pry the camshaft and crankshaft sprocket free, along with the chain.
  8.  



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Fig. Fig. 2: Exploded view of the timing chain and related components - 3.8L (VIN 3) engines

To install:
  1. Make sure the crankshaft is positioned so the No. 1 piston is at TDC.
  2.  
  3. Rotate the camshaft with the sprocket temporarily installed, so the timing mark is straight down.
  4.  
  5. Assemble the timing chain on the sprockets with the timing marks aligned. Install the timing chain and sprocket.
  6.  
  7. Install the cam sensor magnet assembly.
  8.  
  9. Install the oil slinger with the large part of the cone toward the front of the engine, as required.
  10.  
  11. Install the camshaft sprocket bolt, thrust button and spring.
  12.  
  13. Install the timing chain damper and engine front cover.
  14.  
  15. Connect the negative battery cable.
  16.  

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

See Figures 3, through 14

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the front cover, as outlined earlier in this section.
  4.  



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Fig. Fig. 3: View of the timing chain after the cover is removed

  1. On 1988-90 vehicles, remove the camshaft thrust button.
  2.  



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Fig. Fig. 4: If equipped, remove the camshaft thrust button

  1. Align the timing marks on the sprockets, so they are as close together as possible.
  2.  



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Fig. Fig. 5: Align the timing marks, so they are as close together as possible, as shown by the arrows



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Fig. Fig. 6: The timing marks on the camshaft and crankshaft sprockets must be aligned

  1. Remove the spring/damper assembly from the center of the camshaft.
  2.  



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Fig. Fig. 7: Remove the spring from the center of the camshaft ...



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Fig. Fig. 8: ... unfasten the retainer, then remove the damper

  1. Remove the camshaft sprocket bolts, then remove the sprocket and timing chain as an assembly.
  2.  



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Fig. Fig. 9: Unfasten the 3 camshaft sprocket retaining bolts ...



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Fig. Fig. 10: ... then remove the camshaft sprocket and timing chain as an assembly

  1. Remove the crankshaft sprocket. Clean the gasket mounting surfaces and the timing chain and sprockets.
  2.  



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Fig. Fig. 11: View of the camshaft gear after the camshaft sprocket and timing chain have been removed



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Fig. Fig. 12: Remove the camshaft gear from the camshaft



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Fig. Fig. 13: Exploded view of the timing chain and related components - 1990 vehicle shown



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Fig. Fig. 14: Exploded view of the timing chain and related components - 1993 vehicle shown, later models similar

To install:
  1. If the pistons have been moved, while the timing chain was removed, perform the following:
    1. Turn the crankshaft to the No. 1 piston is at Top Dead Center (TDC).
    2.  
    3. Turn the camshaft so, with the sprocket temporarily installed, the timing mark is straight down.
    4.  

  2.  
  3. Assemble the timing chain on the camshaft sprocket and crankshaft sprockets. Make sure to align the marks on the sprockets; they must face each other and be as close together as possible.
  4.  
  5. Slide the assembly onto the camshaft and crankshaft. Install the camshaft sprocket-to-camshaft bolts. Tighten the camshaft sprocket bolts to 27 ft. lbs. (37 Nm) on 1988-91 vehicles. For 1992-99 vehicles, tighten the bolts to 74 ft. lbs. (100 Nm), plus an additional 90° rotation.
  6.  

If equipped with 3.8L (VIN C, L or K) engines, align the camshaft sprocket mark with the balancer shaft sprocket mark.

  1. Install the camshaft thrust button, if equipped, and spring/damper assembly. Tighten the bolt to 14-16 ft. lbs. (19-22 Nm).
  2.  
  3. Install the front cover assembly.
  4.  
  5. Connect the negative battery cable.
  6.  
  7. Refill the cooling system. Start the engine, allow it to reach normal operating temperatures and check for leaks.
  8.  

 
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