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Inspection Procedure

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    Fig 1: Identifying Oil Pump Components
    GM1557735Courtesy of GENERAL MOTORS CORP.
    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)
  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. Fig 2: Identifying Oil Pressure Relief Valve Components
    GM1557740Courtesy of GENERAL MOTORS CORP.
  8. Inspect the 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
    11. Fig 3: Measuring Oil Pump Gear Lash
    GM1557744Courtesy of GENERAL MOTORS CORP.
  11. Measure the oil pump gear lash. Install the gears and measure in several places.
    12. Fig 4: Measuring Oil Pump Housing Gear Pocket
    GM1557747Courtesy of GENERAL MOTORS CORP.
  12. Measure the oil pump housing gear pocket (1, 2).
    13. Fig 5: Measuring Oil Pump Gears
    GM1557750Courtesy of GENERAL MOTORS CORP.
  13. Measure the oil pump gears (1, 2).
    14. Fig 6: Measuring Oil Pump Gear Side Clearance
    GM1557826Courtesy 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.
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