Oil Pump: Service and Repair

Some 1982 engines may exhibit a knock sound similar to a diesel engine. This noise occurs after a previously warmed up engine has sat for 4 hours or longer and been restarted. To alleviate this condition, a new oil filter adapter has been released which has an integral check valve. The new part No. is 4273323, and is used on all later models. When installing this adapter, inspect the check valve for proper operation by inserting a screwdriver in the oil filter end of the adapter and lightly pushing on the check valve. Under very light pressure, the valve should freely move 1/4 inch. If the valve sticks or binds, replace the oil filter adapter. A sticking valve may restrict oil pressure, possibly resulting in engine damage.

Fig. 29 Oil pump assembly:

OIL PUMP ASSEMBLY

1. With oil pan removed, remove the screw securing oil pump to the cylinder block.
2. Reverse procedure to install. Torque oil pump attaching screw to 200 inch lbs.

Fig. 30 Checking oil pump end play:

Fig. 31 Measuring oil pump outer rotor thickness:

Fig. 32 Measuring clearance between oil pump rotors:

OIL PUMP SERVICE

1. Measure the following oil pump clearances:
a. Endplay. Endplay should be 0.001 - 0.006 inch on 1982 vehicles, or 0.001 - 0.004 inch on 1983 - 84 vehicles.
b. Outer rotor thickness. Thickness should be 0.825 inch, minimum. Install outer rotor with chamfered edge in pump body.
c. Clearance between rotors, should be 0.010 inch, maximum.

Fig. 33 Measuring oil pump outer rotor clearance:

Fig. 34 Measuring oil pump cover clearance:

d. Outer rotor clearance. Clearance should be .014 inch, maximum.
e. Oil pump cover clearance, should be no greater than 0.015 inch on 1982 vehicles, or 0.003 inch on 1983 - 84 vehicles.
f. Oil pressure relief valve spring length should be 1.95 inches.