GM Service Manual Online
For 1990-2009 cars only

Disassembly Procedure


    Object Number: 33680  Size: SH
  1. Disassemble the oil pump gerotor cover from the oil pump housing.
  2. Disassemble the oil pump from the balance shaft housing.
  3. Disassemble the pressure relief valve. Remove the roll pin with a punch.
  4. Clean all of the parts in cleaning solvent. Remove varnish, sludge and dirt.

Inspection Procedure

  1. Inspect the pump cover housing for the following conditions:
  2. • Cracks
    • Scoring
    • Porous or damaged casting
    • Damaged threads
    • Excessive wear or galling
  3. Inspect the pressure relief valve for damage. Replace the valve if it is damaged.
  4. Inspect the gerotor for the following conditions:
  5. • Chipping
    • Galling
    • Excessive wear

Measuring Procedure

  1. Measure the following parts:
  2. • The gerotor cavity depth
    • The inner gerotor tip clearance
    • The outer gerotor diameter clearance
    • The gear dimensions
  3. Replace the pump as an assembly if the housing or gears are worn beyond specifications.

Assembly Procedure

  1. Lubricate the gears with clean engine oil.

  2. Object Number: 33683  Size: SH
  3. Assemble the gerotor in the housing.
  4. Notice: Fill oil pump cavities with petroleum jelly prior to installation. This will ensure that there is oil pressure immediately on start-up and will prevent engine damage.

  5. Prime the oil pump with petroleum jelly.

  6. Object Number: 33685  Size: SH
  7. Assemble the pressure relief valve.

  8. Object Number: 33688  Size: SH
  9. Assemble the pump housing to the balance shaft assembly.
  10. Assemble the pump cover to the oil pump housing.