GM Full-Size Trucks 1988-1998 Repair Information

Oil Pump

Print

REMOVAL & INSTALLATION



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

See Figures 1, 2 and 3

  1. Remove the oil pan.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of oil pump-4.3L engines



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of oil pump-5.0L and 5.7L engines



Click image to see an enlarged view

Fig. Fig. 3: Exploded view of 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.  

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.  

4.8L Engines

See Figure 4

  1. Raise and support the truck on jackstands.
  2.  



Click image to see an enlarged view

Fig. Fig. 4: Exploded view of oil pump-4.8L engines

  1. Remove the oil pan.
  2.  
  3. Remove the oil pump tube bracket main bearing cap nut.
  4.  
  5. Remove the oil pump bolts and the oil pump.
  6.  

To install:
  1. Position the oil pump to the engine and align the slot in the oil pump shaft with the tang on the distributor shaft. The oil pump should slide easily in place.
  2.  
  3. Install the oil pump bolts and tighten to 115 inch lbs. (11 Nm).
  4.  
  5. Install the oil pump pick-up tube to the main bearing cap nut and tighten to 25 ft. lbs. (37 Nm).
  6.  
  7. Install the oil pan.
  8.  

6.2L and 6.5L 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.  

 
label.common.footer.alt.autozoneLogo