S&T Series Blazer, Bravada, Envoy, Jimmy, Rainier, Trailblazer, Xtreme

Oil Pump

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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.  

4.3L Engine
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    Be careful not to crack the retainer.



    Oil pan
     
    Oil pump and the pickup tube/shaft, if equipped
     

  4.  

To install:

  1. Ensure that the pump pickup tube is tight in the pump body. If the tube should come loose, oil pressure will be lost and oil starvation will occur. If the pickup tube is loose it should be replaced.
  2.  
  3. If the pump has been disassembled and is being replaced or for any reason oil has been removed, 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.
    WARNING
    If the pump is not primed, the engine could be damaged upon start up.

  4.  
  5. Install or connect the following:
    NOTE
    If the oil pump does not build up oil pressure almost immediately, remove the pan and check for a loose oil pump-to-pickup tube attachment. If necessary dismantle the pump and pack the pump cavity with petroleum jelly.



    Oil pump by aligning the pump shaft with the distributor drive gear as necessary. Tighten oil pump/pickup tube retainer(s) to 65 ft. lbs. (90 Nm).
     



    Oil pan
     

  6.  
  7. Refill the crankcase.
  8.  
  9. Disable the ignition system; crank engine for approximately 10 seconds to aid in priming the oil pump and reducing the risk of engine damage.
    WARNING
    Running the engine without measurable oil pressure will cause extensive damage.

  10.  

5.3L Engine
  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 engine

     

  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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