Oil Pump Service

Fig. 26 Oil Pump Components:

It is necessary to remove oil pan, oil pickup and chain case cover to service oil pump rotors. Oil pump relief valve can be serviced by removing oil pan and oil pickup tube.

DISASSEMBLE

Fig. 27 Oil Pressure Relief Valve Components:

1. Remove relief valve as follows:
a. Drill a 1/8 inch (3.175 mm) hole into relief valve retainer cap, then insert a self-threading sheet metal screw into cap.
b. Clamp screw in a vise, then while supporting Chain Case Cover (CCC), remove cap by tapping CCC with a soft hammer.
c. Discard retainer cap, then remove relief spring and relief valve.

2. Remove oil pump cover screws, then lift off cover.
3. Remove pump rotors.
4. Wash all parts in a suitable solvent and inspect for damage or wear.

INSPECTION & REPAIR

1. Clean all parts thoroughly. Mating surfaces of cover should be smooth. Replace pump cover if scratched or grooved.

Fig. 28 Oil Pump Cover Flatness Inspection:

2. Lay a straightedge across pump cover surface. If a 0.003 inch feeler gauge can be inserted between cover and straightedge, replace cover.

Fig. 29 Outer Rotor Thickness Inspection:

3. Measure thickness and diameter of outer rotor. If outer rotor thickness measures 0.301 inch or less, or if diameter is 3.148 inches or less, replace outer rotor.

Fig. 30 Inner Rotor Thickness Inspection:

4. If inner rotor thickness measures 0.301 inch or less, replace inner rotor and shaft assembly.

Fig. 31 Outer Rotor Clearance In Case Inspection:

5. Install outer rotor into cover, press one side with fingers and measure clearance between outer rotor and cover. If measurement is 0.015 inch or more, if outer rotor is within specifications, replace cover only.

Fig. 32 Rotor Clearance Inspection:

6. Install inner rotor into cover, then measure clearance between inner and outer rotors. If clearance measured between rotors is 0.008 inch or more, replace both rotors.

Fig. 33 Rotor To Case Clearance Inspection:

7. Place a straightedge across face of CCC between bolt holes. If a feeler gauge of 0.004 inch or more can be inserted between rotors and straightedge, replace pump assembly.
8. Inspect oil pressure relief valve plunger for scoring and free operation in it's bore. Small marks can be removed with 400 grit wet or dry sandpaper.
9. Relief valve spring has a free length of approximately 1.95 inches and should test between 19.5-20.5 pounds when compressed to 1 11/32 inches. Replace spring that does not meet specifications.

ASSEMBLE & INSTALLATION

Fig. 26 Oil Pump Components:

Fig. 27 Oil Pressure Relief Valve Components:

1. Assemble oil pump as shown using new parts as required.
2. Tighten oil pump cover screws to specifications.
3. Prime oil pump prior to installation by filling rotor cavity with engine oil.
4. Refer to procedure described under Timing Chain Service to install timing chain case cover.