Oil Pump: Service and Repair

REMOVAL

1. Remove oil pan as previously described.
2. Straighten tab of lock washer and remove oil pump sprocket attaching nut.
3. Remove oil pump to block attaching bolts.
4. Remove sprocket from pump shaft.
5. Remove oil pump.

DISASSEMBLY, INSPECTION & ASSEMBLY

1. Remove adjusting shims and O-rings, then the shaft key.
2. Remove pump cover attaching bolts and the cover.
3. Remove pump shaft and rotors, then the pin from the shaft.
4. Remove split pin and the oil pressure regulator assembly.
5. Visibly check disassembled parts, replacing as necessary. Check sliding surface of pump cover with special care and replace cover if surface has steps or excessive streaks. Minor steps and streaks may be repaired by rubbing them with a compound on a surface plate.
6. Using dial gauge, measure clearance between pump body and shaft. If clearance exceeds .0039 inch (.1 mm), replace pump drive shaft inner rotor, pump body and drive gear.
7. Check clearance between lobes of rotors. If clearance exceeds .01 inch (.25 mm), replace both rotors.
8. Check clearance between outer rotor and pump body. If clearance exceeds .012 inch (.3 mm), replace rotor or pump body.
9. Check end float of rotors, then measure clearance between straightedge and cover. If total of these to measurements exceeds .006 inch (.15 mm), repair or replace pump body or cover.
10. Reverse disassembly procedure to assemble. When installing rotors into body, ensure tally marks on rotors are positioned toward cover.. Torque cover attaching bolts to 6-8 ft.lbs.

INSTALLATION

1. Reverse removal procedure to install, noting the following:
a. Check slack of oil pump drive chain by pressing with finger at right side just above sprocket.
b. If slack exceeds .157 inch, install adjusting shim(s) between cylinder block and oil pump body.
c. Torque oil pump sprocket attaching nut to 22-25 ft.lbs.