GM Full Size Vans 1967-1986 Repair Guide

Timing Chain

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REMOVAL & INSTALLATION



Gasoline V6 and V8 Engines

See Figures 1 through 5



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Fig. Fig. 1: Make sure the timing gears aligned before removal; this will aid in installation



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Fig. Fig. 2: Unfasten the camshaft gear retaining bolts ...



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Fig. Fig. 3: ... then remove the camshaft gear and the chain



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Fig. Fig. 4: Using a puller, remove the crankshaft gear



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Fig. Fig. 5: Timing sprocket alignment

To replace the chain, remove the radiator core, water pump, the harmonic balancer and the crankcase front cover. This will allow access to the timing chain. Crank the engine until the timing marks on both sprockets are nearest each other and in line between the shaft centers. Then take out the three bolts that hold the camshaft gear to the camshaft. This gear is a light press fit on the camshaft and will come off easily. It is located by a dowel.

The chain comes off with the camshaft gear.

A gear puller will be required to remove the crankshaft gear.

Without disturbing the position of the engine, mount the new crankshaft gear on the shaft, and mount the chain over the camshaft gear. Arrange the camshaft gear in such a way that the timing marks will line up between the shaft centers and the camshaft locating dowel will enter the dowel hole in the cam sprocket.

Place the cam sprocket, with its chain mounted over it, in position on the front of the car and pull up with the three bolts that hold it to the camshaft.

After the gears are in place, turn the engine two full revolutions to make certain that the timing marks are in correct alignment between the shaft centers.

End-play of the camshaft is zero.

6.2L Diesel Engine

See Figure 6



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Fig. Fig. 6: Exploded view of the diesel engine timing chain assembly and alignment marks

  1. Remove the front cover as previously detailed.
  2.  
  3. Remove the bolt and washer attaching the camshaft gear. Remove the injection pump gear.
  4.  
  5. Remove the camshaft sprocket, timing chain and crankshaft sprocket as a unit.
  6.  
  7. To install, the cam sprocket, timing chain and crankshaft sprocket as a unit, aligning the timing marks on the sprockets as shown in the illustration.
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  9. Rotate the crankshaft 360° so that the camshaft gear and the injection pump gear are aligned.
  10.  
  11. Install the front cover as previously detailed. The injection pump must be retimed since the timing chain assembly was removed. See Engine Electrical for this procedure.
  12.  

 
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