Oil Pump Service

Fig. 31 Oil Pump Assembly:

1. Lay a straightedge across oil pump cover surface. If a 0.003 in. feeler gauge blade can be inserted between straightedge and cover, or if surface is scratched or grooved, replace cover.
2. Measure thickness and diameter of both rotors. If thickness of either rotor is 0.744 in. -or less- or if diameter is 3.246 in. -or less- replace rotor set.
3. Slide outer rotor into timing chain cover pump body, then press rotor to one side and measure clearance between rotor and body. If clearance is 0.007 in. -or more- replace timing chain cover.
4. Install inner rotor in timing chain cover pump body with chamfer up. If distance between rotors is 0.006 in. -or more- replace rotor set.
5. Place a straightedge across face of timing chain cover pump body, between bolt holes. If a 0.003 in. feeler gauge blade can be inserted between rotors and straightedge, and rotors are within specifications, replace timing chain cover.
6. Inspect oil pressure relief valve plunger for scoring. Remove small marks with 400 grit wet/dry sandpaper, then ensure plunger operates freely in bore.
7. Ensure relief valve spring free length is approximately 1.95 inches, then compress to 1.34 in. Spring should exert between 22.5 and 24.5 lbs. force. Replace spring if not within specifications.