Oil Pump: Service and Repair

REMOVAL

Fig.111:

The oil pump is contained within the timing chain cover housing (Fig. 111).
1. Remove oil pan.
2. Remove the timing chain cover.
3. Disassemble oil pump from timing chain cover.
4. Clean and Inspect oil pump components.

DISASSEMBLY
1. Remove oil pump cover screws, and lift off cover (Fig. 111).
2. Remove oil pump rotors (Fig. 111).
3. Clean and inspect oil pump components.

CLEANING
1. Clean all parts thoroughly in a suitable solvent.

INSPECTION
1. Inspect mating surface of the chain case cover. Surface should be smooth. Replace cover if scratched or grooved.

Fig.112:

2. Lay a straightedge across the pump cover surface (Fig. 112). If a 0.025 mm (0.001 in.) feeler gauge can be inserted between cover and straight edge, cover should be replaced.

Fig.113:

3. Measure thickness and diameter of outer rotor. If outer rotor thickness measures 7.64 mm (0.301 in.) or less (Fig. 113), or if the diameter is 79.95 mm (3.148 in.) or less, replace outer rotor.

Fig.114:

4. If inner rotor thickness measures 7.64 mm (0.301 in.) or less, replace inner rotor (Fig. 114).

Fig.115:

5. Install outer rotor into chain case cover. Press rotor to one side with fingers and measure clearance between rotor and chain case cover (Fig. 115). If measurement is 0.39 mm (0.015 in.) or more, replace chain case cover, only if outer rotor is in specification.

Fig.116:

6. Install inner rotor into chain case cover. If clearance between inner and outer rotors (Fig. 116) is 0.203 mm (0.008 in.) or more, replace both rotors.

Fig.117:

7. Place a straightedge across the face of the chain case cover, between bolt holes. If a feeler gauge of 0.10 mm (0.004 in.) or more can be inserted between rotors and the straightedge, replace pump assembly (Fig. 117). ONLY if rotors are in specs.
8. Remove oil pressure relief valve.

Fig.118:

9. Inspect oil pressure relief valve and bore. Inspect for scoring, pitting and free valve operation in bore (Fig. 118). Small marks may be removed with 400-grit wet or dry sandpaper.
10. The relief valve spring has a free length of approximately 49.5 mm (1.95 inches) it should test between 19.5 and 20.5 pounds when compressed to 34 mm (1-11/32 inches). Replace spring that fails to meet specifications.
11. If oil pressure is low and pump is within specifications, inspect for worn engine bearings or other reasons for oil pressure loss.

ASSEMBLY
1. Assemble pump, using new parts as required. Install the inner rotor with chamfer facing the cast iron oil pump cover.
2. Prime oil pump before installation by filling rotor cavity with engine oil.
3. Install cover and tighten screws to 12 Nm (105 in. lbs.).
4. If removed, install the oil pressure relief valve.

INSTALLATION
1. Install oil pump.
2. Install timing chain cover and oil pan.