Oil Pump: Service and Repair
REMOVAL
1. Remove oil pan as previously described.
2. Remove pump and driveshaft extension.
Fig. 15 Exploded View Of Oil Pump:
DISASSEMBLY
1. Drain oil from pump.
2. Remove pump cover and pump gears, Fig. 15.
3. Remove pressure regulator valve. If valve is stuck, sock pump housing in carburetor cleaning solvent. Pressure regulator valve spring may be under pressure. Remain retaining pin carefully.
4. Clean sludge, oil and/or varnish from all parts. Varnish may be removed by soaking in carburetor or cleaning solvent.
INSPECTION
1. Inspect pump housing and cover for cracks or damaged threads, replacing as necessary. Do not attempt to repair pump housing. Replace spring as necessary.
2. Inspect idler gear shaft. If loose in housing, replace pump.
3. Inspect pressure regulator valve for scoring or sticking. Burrs may be removed with a fine oil stone.
4. Inspect pressure regulator valve spring for loss of tension or bending.
5. Inspect suction pipe and screen assembly for looseness if permanently pressed into pump body. If pipe is loose or has been removed, pump body cover must be replaced. Check for broken wire mesh or screen.
6. Inspect gears for chipping, galling or wear.
Fig. 16 Measuring Oil Pump Gear Lash:
7. Measure gear lash in several positions, Fig. 16, as follows:
a. On 1989 models, gear lash should be .009-.015 inch.
b. On 1990 models except 1990 Grand Prix STE and Lumina, gear lash should be .0037-.0077 inch.
c. On 1990 Lumina models, gear lash should be .009-.015 inch.
d. On 1990 Grand Prix STE models, gear lash should be .004-.008 inch.
e. On 1991-92 models, gear lash should be .0037-.0077 inch.
Fig. 17 Measuring Oil Pump Gear Pocket:
8. Measure pump housing gear pocket depth, Fig. 17.
as follows:
a. On 1989 models, pump depth should be 1.195-1.195 inches.
b. On 1990-92 models with an aluminum pump body, pump depth should be 1.195-1.198 inches.
c. On 1990-92 models with a cast pump body except 1990 Grand Prix STE, pump depth should be 1.202-1.205 inches.
d. On 1990 Grand Prix STE models, pump depth should be 1.434-1.436 inches.
Fig. 17 Measuring Oil Pump Gear Pocket:
9. Measure pump housing gear pocket diameter, Fig.
17. as follows:
a. Pump housing diameter should be 1.503-1.506 inches.
Fig. 18 Measuring Oil Pump Gears:
10. Measure pump gear diameters, Fig. 18, as follows:
a. On 1989 models, gear diameter should be 1.498-1.500 inches.
b. On 1990 Lumina models, gear diameter should be 1.498-1.500 inches.
c. On 1990-92 models except 1990 Lumina, gear diameter should be 1.498-1.500 inches.
Fig. 18 Measuring Oil Pump Gears:
11. Measure pump gear length, Fig. 18, as follows:
a. On except 1990 Grand Prix STE models, gear length should be 1.199-1.200 inches.
b. On 1990 Grand Prix STE models, gear length should be 1.438-1.439 inches.
Fig. 19 Measuring Gear Side Clearance:
12. Measure pump gear side clearance, Fig. 19, as follows:
a. On except 1990 Grand Prix STE models, gear side clearance should be .003-.004 inches.
b. On 1990 Grand Prix STE models, gear side clearance should be .0025-.0040 inches.
Fig. 20 Measuring Oil Pump End Clearance:
13. Measure oil pump end clearance, Fig. 20, as follows:
a. On all 1989 models and 1990 Lumina models, end clearance should be .002-.005 inch.
b. On 1990-92 models with an aluminum pump body except 1990 Lumina, end clearance should be .0016-.0067 inch.
c. On 1990-92 models with a cast pump body except 1990 Grand Prix STE, end clearance should be .002-.006 inch.
d. On 1990 Grand Prix STE models, end clearance should be .003-.007 inch.
ASSEMBLY
1. Lubricate all internal parts with engine oil.
2. Install pump gears.
3. Prime engine oil galleries by removing engine oil pump drive unit and rotating oil pump, using drill motor, appropriate socket and extension.
4. Install cover and gasket. Use only original equipment gaskets as gasket thickness is critical to proper pump operation.
5. Install pin, ensuring it is properly secured.
6. Torque pump cover attaching bolts to 89 inch. lbs.
INSTALLATION
1. Apply sealer No. 1050026, Fel-Pro set and seal, or equivalents to new pipe and tap into place with a plastic hammer, using oil suction pipe installer tool No. J-21182 or equivalent.
2. Install oil pump and driveshaft extension, engaging driveshaft extension into drive gear.
3. Install pump to rear bearing cap bolt, torquing to specifications.
4. Clean oil pan of oil and sludge and replace oil filter.
5. Install oil pan, then fill crankcase and check oil pressure. If pressure does not build up almost immediately, remove oil pan and check oil pump suction pipe attachment to pump. If necessary, disassemble oil pump, fill all cavities with petroleum jelly and reassemble. Running engine without measurable oil pressure will cause extensive damage.