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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1675 (Engine Mechanical - 3.1L V6 - VIN (J)) >> Repair Instructions >> Off-Vehicle Repair Instructions >> Oil Pump Cleaning and Inspection

Oil Pump Cleaning and Inspection

WARNING: This page is about a different car, the 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Refer to Cleaning Solvent Caution in Cautions and Notices.
  1. Clean all parts of sludge, oil, and varnish by soaking in cleaning solvent.
  2. Inspect for foreign material and determine the source of the foreign material.
  3. Inspect the pump housing and cover for the following conditions:
    • Cracks or casting imperfections
    • Scoring (3)
    • Damaged threads
  4. Do not attempt to repair the pump housing. Replace the pump housing.
  5. Inspect the oil pump gears for the following conditions:
    • Scoring (1)
    • Excessive wear (2)
      Fig 1: Identifying Oil Pump & Gear Wear & Damage
      G01968143Courtesy of GENERAL MOTORS CORP.
  6. Inspect the idler shaft for looseness or scoring (4). If loose or damaged, replace the oil pump.
  7. Inspect the drive gear shaft for looseness or scoring (5).
  8. Inspect the pressure regulator valve for the following conditions:
    • Scoring
    • Sticking

      Burrs may be removed using a fine oil stone.

  9. Inspect the pressure regulator valve spring for the following conditions:
    • Loss of tension
    • Bending
  10. Inspect the suction pipe and screen assembly for the following conditions:
    • Looseness

      If the suction pipe is loose, bent or has been removed, replace the pump body cover and suction pipe.

    • Broken wire mesh or screen
      Fig 2: View Of Pressure Regulator Valve Spring
      G01968144Courtesy of GENERAL MOTORS CORP.
  11. Measure the oil pump gear lash. Install the gears, and measure in several places.
    Fig 3: Measuring Oil Pump Gear Lash
    G01968145Courtesy of GENERAL MOTORS CORP.
  12. Measure the oil pump housing gear pocket (1, 2).
    Fig 4: Identifying Oil Pump Housing Gear Pocket Measurements
    G01968146Courtesy of GENERAL MOTORS CORP.
  13. Measure the oil pump gears (1, 2).
    Fig 5: Checking Measurements On Oil Pump Gears
    G01968147Courtesy of GENERAL MOTORS CORP.
    IMPORTANT: When deciding pump serviceability based on end clearance, consider depth of the wear pattern in the pump cover.
  14. Measure the oil pump gear side clearance.
    Fig 6: Measuring Oil Pump Gear Side Clearance
    G01968148Courtesy of GENERAL MOTORS CORP.
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