GM Full Size Vans 1987-1997 Repair Guide

Oil Pump

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REMOVAL & INSTALLATION



4.3L, 5.0L, 5.7L and 7.4L Engines

See Figures 1 through 4

  1. Remove the oil pan.
  2.  



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Fig. Fig. 1: Oil pump - 1987-95 4.3L engines



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Fig. Fig. 2: Exploded view of the oil pan mounting - 1996-97 models



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Fig. Fig. 3: Oil pump - 5.0L and 5.7L engines



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Fig. Fig. 4: Oil pump - 7.4L engines

  1. Remove the bolt attaching the pump to the rear main bearing cap. Remove the pump and the extension shaft, which will come out behind it.
  2.  



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Fig. Fig. 5: Loosen the oil pump retaining bolt(s) ...



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Fig. Fig. 6: ... then remove the oil pump and extension shaft from the engine

To install:
  1. If the pump has been disassembled, is being replaced, or for any reason oil has been removed from it, it must be primed. It can either be filled with oil before installing the cover plate (and oil kept within the pump during handling), or the entire pump cavity can be filled with petroleum jelly.
  2.  

If the pump is not primed, the engine could be damaged before it receives adequate lubrication when you start it.

  1. Engage the extension shaft with the oil pump shaft. Align the slot on the top of the extension shaft with the drive tang on the lower end of the distributor driveshaft, and then position the pump at the rear main bearing cap so the mounting bolt can be installed. The installed position of the oil pump screen is with the bottom edge parallel to the oil pan rails. Install the bolt, tightening to 65 ft. lbs. (90 Nm).
  2.  
  3. Install the oil pan.
  4.  

6.2L and 6.5L Diesel Engines
1987-95 MODELS

See Figure 5



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Fig. Fig. 7: Common oil pan and pump mounting - diesel engines

  1. Drain the oil.
  2.  
  3. Lower the oil pan enough to gain access to the pump.
  4.  
  5. Rotate the crankshaft so that the forward crankshaft throw and No. 1 and No. 2 connecting rod journals are up.
  6.  
  7. Remove the bolt retaining the pump to the main bearing cap. Let the pump and extension shaft fall into the pan.
  8.  
  9. Remove the pan from the vehicle.
  10.  

To install:
  1. Maneuver the pan, pump and extension shaft into position.
  2.  
  3. Position the pump on the bearing cap.
  4.  
  5. Align the extension shaft hex with the drive hex on the oil pump drive or vacuum pump. The pump should push easily into place. Install the pump and tighten the bolt to 65 ft. lbs. (90 Nm).
  6.  
  7. Install the pan and fill the engine with oil.
  8.  

1996-97 MODELS
  1. Remove the oil pump.
  2.  
  3. Remove the bolt attaching the pump to the rear main bearing cap. Remove the pump and the hex drift.
  4.  

To install:
  1. If the pump has been disassembled, is being replaced, or for any reason oil has been removed from it, it must be primed. It can either be filled with oil before installing the cover plate (and oil kept within the pump during handling), or the entire pump cavity can be filled with petroleum jelly.
  2.  

If the pump is not primed, the engine could be damaged before it receives adequate lubrication when you start it.

  1. Install the oil pump and extension shaft.
  2.  
  3. Align the extension shaft hex with the drive hex and push the pump into place.
  4.  
  5. Install the bolt, tightening to 65 ft. lbs. (90 Nm).
  6.  
  7. Install the oil pan.
  8.  

INSPECTION



  1. Inspect the pump body for wear, cracks or other damage.
  2.  
  3. Inspect the inside of the pump cover for cracks or wear that might allow oil to leak past the gear ends.
  4.  
  5. Inspect the gears for wear.
  6.  
  7. Inspect the drive gear and shaft for improper fit in the pump body.
  8.  
  9. Inspect the pick-up screen and pipe for damage and/or loose fit.
  10.  
  11. Check that the pressure regulator valve slides freely in its bore without sticking or binding.
  12.  
  13. Oil pump gears, cover and body are serviced as a unit. If any single part is damaged, replace the entire assembly.
  14.  

 
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