Oil Pump Cleaning and Inspection

WARNING: This page is about a different car, the 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

Clean all parts of sludge, oil, and varnish by soaking in cleaning solvent.
Inspect for foreign material and determine the source of the foreign material.
Inspect the pump housing and cover for the following conditions:
- Cracks or casting imperfections
- Scoring (3)
- Damaged threads
Do not attempt to repair the pump housing. Replace the pump housing.
Inspect the oil pump gears for the following conditions:
- Scoring (1)
- Excessive wear (2)
Inspect the idler shaft for looseness or scoring (4). If loose or damaged, replace the oil pump.
Inspect the drive gear shaft for looseness or scoring (5).

Fig 1: Oil Pump Housing And Gears
Courtesy of GENERAL MOTORS CORP.
Inspect the pressure regulator valve for the following conditions:
- Scoring
- Sticking
- Burrs may be removed using a fine oil stone.
Inspect the pressure regulator valve spring for the following conditions:
- Loss of tension
- Bending
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: Pressure Regulator Valve Spring
Courtesy of GENERAL MOTORS CORP.
Measure the oil pump gear lash. Install the gears, and measure in several places.

Fig 3: Measure The Oil Pump Gear Lash
Courtesy of GENERAL MOTORS CORP.
Measure the oil pump housing gear pocket (1, 2).

Fig 4: Measure The Oil Pump Housing Gear Pocket
Courtesy of GENERAL MOTORS CORP.
Measure the oil pump gears (1, 2).

Fig 5: Measure The Oil Pump Gears
Courtesy of GENERAL MOTORS CORP.

NOTE: When deciding pump serviceability based on end clearance, consider depth of the wear pattern in the pump cover.
Measure the oil pump gear side clearance.

Fig 6: Measure The Oil Pump Gear Side Clearance
Courtesy of GENERAL MOTORS CORP.