Envoy, Rainer, Trailblazer 2006-2007

Oil Pump

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Inspection



4.2L Engine
  1. Clean all parts of sludge, oil, and varnish by soaking in carburetor cleaner or cleaning solvent.
  2.  
  3. Inspect for foreign material and determine the source of the foreign material.
  4.  
  5. Inspect the oil pump housing and engine front cover for the following conditions:

    Cracks or casting imperfections
     
    Scoring
     
    Damaged threads
     

  6.  
  7. Do not attempt to repair the oil pump housing. Replace the oil pump housing if damage is found.
  8.  
  9. Inspect the oil pump gears for damage.
  10.  
  11. Measure the oil pump gears against the following specifications:

    Drive Gear Diameter-2.893-2.891 inches (73.415-73.370mm) 
     
    Driven Gear Diameter-3.428-3.426 inches (87-86.975mm) 
     
    Gear Pocket - Depth-0.615-0.614 inch (15.609-15.584mm)
     
    Gear Pocket - Diameter-3.430-3.429 inches (87.065-87.040mm)
     
    Drive Gear Thickness-0.613-0.611 inch (15.546-15.521mm)
     
    Driven Gear Thickness: 15.360-15.511 mm0.605-0.611 in
     
    Lobe Inner Diameter - Maximum:11.9 mm0.469 in
     
    Relief Valve-to-Bore Clearance2.57-1.63 mm0.101-0.064 in

    Click image to see an enlarged view

    Fig. Measure the inner oil pump gear tip clearance in several places-4.2L engine



    Click image to see an enlarged view

    Fig. Measure the outer oil pump gear tip clearance in several places-4.2L engine

     

  12.  
  13. Measure the inner oil pump gear tip clearance in several places.
  14.  
  15. Measure the outer oil pump gear tip clearance in several places.
    NOTE
    When deciding oil pump serviceability based on end clearance, consider depth of the wear pattern in the pump cover.



    Click image to see an enlarged view

    Fig. Measure the oil pump gear side clearance-4.2L engine

  16.  
  17. Measure the oil pump gear side clearance.
  18.  
  19. Inspect the pressure regulator valve for the following conditions:

    Scoring
     
    Sticking
     
    Burrs -- Burrs may be removed using a fine oil stone
     

  20.  
  21. Inspect the pressure regulator valve spring for loss of tension or bending. Replace the pressure regulator spring if damaged.
  22.  
  23. Inspect the oil pump pipe pickup tube and screen assembly for the following conditions:

    Looseness -- If the oil pump pipe pickup tube is loose or bent, replace the oil pump pipe pickup tube.
     
    Broken wire mesh or screen
     
    Inspect the O-ring seal at the base of the oil pump pickup tube for damage
     

  24.  

5.3L & 6.0L Engines

NOTE
The internal parts of the oil pump assembly are not serviced separately, excluding the spring. If the oil pump components are worn or damaged, replace the oil pump as an assembly. The oil pump pipe and screen are to be serviced as an assembly. Do not attempt to repair the wire mesh portion of the pump and screen assembly.



Click image to see an enlarged view

Fig. Exploded view of the oil pump housing assembly-5.3L and 6.0L engines

  1. Clean the parts in solvent and dry the parts with compressed air.
  2.  
  3. Inspect the oil pump housing (413) and the cover (409) for cracks, excessive wear, scoring, or casting imperfections.
  4.  
  5. Inspect the oil pump housing-to-engine block oil gallery surface for scratches or gouging.
  6.  
  7. Inspect the oil pump housing for damaged bolt hole threads.
  8.  
  9. Inspect the relief valve plug (416) and plug bore for damaged threads.
  10.  
  11. Inspect the oil pump internal oil passages for restrictions.
  12.  
  13. Inspect the drive gear (410) and driven gear (412) for chipping, galling or wear.
  14.  
  15. Minor burrs or imperfections on the gears may be removed with a fine oil stone.
  16.  
  17. Inspect the drive gear splines for excessive wear.
  18.  
  19. Inspect the pressure relief valve (414) and bore for scoring or wear.
  20.  
  21. The valve must move freely in the bore with no restrictions.

    Click image to see an enlarged view

    Fig. Exploded view of the oil pump screen assembly-5.3L and 6.0L engines

  22.  
  23. Inspect the oil pump screen (407) for debris or restrictions.
  24.  
  25. Inspect the oil pump screen for broken or loose wire mesh.
    NOTE
    Prior to assembling the oil pump, coat all wear or internal surfaces with clean engine oil.

  26.  
  27. Install the driven gear (412) into the pump housing (413).
  28.  
  29. Install the driven gear with the orientation mark facing the pump cover.
  30.  
  31. Install the drive gear (410) into the pump housing.
  32.  
  33. Install the oil pump cover (409) and tighten the oil pump cover bolts (408) to 106 inch lbs. (12 Nm).
  34.  
  35. Install the relief valve (414) and relief valve spring (415).
  36.  
  37. Install the relief valve plug (416) and tighten to 106 inch lbs. (12 Nm).
  38.  
  39. Inspect the oil pump for smooth operation by rotating the drive gear.
  40.  

Removal & Installation



4.2L Engine
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Engine front cover
     
    Oil pump cover bolts
     
    Oil pump cover. Mark the inner and outer gears in relation to the pump housing.
     
    Inner and outer pump gears
     
    Oil pump pressure relief valve plug
     
    Oil pump pressure relief valve and spring
     

  4.  

To install:

  1. Install or connect the following:

    Oil pump pressure relief valve and spring
     
    Oil pump pressure relief valve plug. Tighten to 10 ft. lbs. (14 Nm).
     
    Oil pump outer and inner gears, as marked during removal
     
    Oil pump cover and bolts. Tighten the bolts to 89 inch lbs. (10 Nm).
     
    Front cover
     

  2.  

5.3L & 6.0L Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    Do not let any dirt or debris into the oil pump or cap end.



    Oil pan
     
    Engine front cover
     
    Oil pump screen bolt and nuts
     
    Oil pump screen with O-ring seal
     
    O-ring seal from the pump screen. Discard the O-ring seal.
     
    Remaining crankshaft oil deflector nuts
     
    Crankshaft oil deflector
     
    Oil pump bolts
     
    Oil pump
     



    Clean and inspect the oil pump.

    Click image to see an enlarged view

    Fig. Exploded view of the oil pump mounting-5.3L and 6.0L engines

     

  4.  

To install:

  1. Align the splined surfaces of the crankshaft sprocket and the oil pump drive gear and install the oil pump.
  2.  
  3. Install or connect the following:
    NOTE
    Push the oil pump screen tube completely into the oil pump prior to tightening the bolt. Do not let the bolt pull the tube into the pump.



    Oil pump onto the crankshaft sprocket until the pump housing contacts the face of the engine block
     
    Oil pump bolts and tighten to 18 ft. lbs. (25 Nm)
     
    Crankshaft oil deflector and nuts until snug
     
    New oil pump screen O-ring seal into the oil pump screen, after lubricating with clean engine oil
     

  4.  
  5. Align the oil pump screen mounting brackets with the correct crankshaft bearing cap studs.

    Oil pump screen
     
    Oil pump screen bolts and nuts. Tighten the bolts to 106 inch lbs. (12 Nm) and the nuts to 18 ft. lbs. (25 Nm).
     
    Engine front cover
     
    Oil pan
     

  6.  

 
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