Oil Pump Unit Repair

OIL PUMP UNIT REPAIR





Tool Required: J 21882 Oil Suction Tube Installer


Disassemble
1. Drain oil from pump.
2. Drive shaft (18).

Important: Do not remove pickup tube from cover unless loose or broken.

3. Pump cover bolts and cover.
4. Pump gears.

CAUTION: The pressure regulator valve spring in some models is under pressure. Exercise caution when removing the retaining pin, as bodily injury may result.

5. Pressure regulator valve.
^ Cotter pin.
^ Spring.
^ Valve. If the valve is stuck, soak the pump housing in carburetor cleaning solvent.

CAUTION: Avoid breathing of fumes or exposure of the skin to the cleaning solvent, as bodily injury may result.


Clean
^ All parts of sludge, oil and varnish.
^ Varnish may be removed by soaking in carburetor or cleaning solvent.


Inspect
^ For foreign material and determine source.
^ Pump housing and cover for:
- Cracks.
- Scoring.
- Casting imperfections.
- Damaged threads.
- Do not attempt to repair the pump housing.
- If in doubt, replace the spring.

^ Idler gear shaft. If loose in the housing, replace the pump.
^ Pressure regulator valve for:
- Scoring.
- Sticking. Burrs may be removed with a fine oil stone.

^ Pressure regulator valve spring for:
- Loss of tension.
- Bending.

^ Suction pipe and screen assembly for:
- Looseness, if permanently pressed into the pump body. If the suction pipe is loose, or has been removed, the pump body cover and suction pipe must be replaced.
- Broken wire mesh or screen.

^ Gears for:
- Chipping.
- Galling.
- Wear.

^ Drive shaft and drive shaft extension for:
- Looseness.
- Wear.



Measure




^ Gear lash. Install gears, and measure in several places (Figure 44).





^ Pump housing gear pocket (Figure 45).





^ Gears (Figure 46).





^ Gear side clearance (Figure 47).





^ Gear end clearance (Figure 48).

Important When deciding pump serviceability based on end clearance, consider depth of wear pattern in the pump cover.


Assemble
1. Lubricate all internal parts with engine oil during assembly.
2. Pump gears.

NOTICE: To avoid engine damage, use only original equipment gaskets. The gasket thickness is critical to proper functioning of the pump.

3. Cover and gasket.
Tighten Pump cover bolts to 10 N.m (89 lb. in.).

4. Pressure regulator valve and spring.

Important: Make sure the cotter pin is properly secured.

5. Cotter pin.
6. Apply sealer GM p/n 1050026 (or equivalent), to a new pipe, and tap into place with a plastic hammer, using J 21882.

Important Whenever the oil pump is overhauled, clean the oil pan of oil and sludge; replace the oil filter; and fill crankcase with clean oil.


Inspect
1. Oil pressure as follows:
A. Prime engine oil galleries by removing engine oil pump drive unit and rotate oil pump drive shaft using drill motor and appropriate socket and extension.
B. Remove the oil pressure sending unit and install a pressure gage.

NOTICE: If the oil pressure does not build up almost immediately, remove the oil pan and check oil pump suction pipe attachment to the pump. Running the engine without measurable oil pressure will cause extensive damage.