Fig. 3 Oil Pan Sealing

(7) Fill crankcase with oil to proper level.

OIL PUMP SERVICE

It is necessary to remove the oil pan, oil pickup and chain case cover (CCC) to service the oil pump rotors. The oil pump pressure relief valve can be serviced by removing the oil pan and oil pickup tube. Refer to Timing Chain Cover Removal and Installation of this section for procedures.

DISASSEMBLY

(1)To remove the relief valve, proceed as follows:

(a)Drill a 3.175mm (1/8 inch) hole into the relief valve retainer cap and insert a self-threading sheet metal screw into cap.

(b)Clamp screw into a vise and while supporting chain case cover (CCC), remove cap by tapping CCC using a soft hammer. Discard retainer cap and remove spring and relief valve (Fig. 5).

Fig. 4 Oil Pan Gasket Installation

(2)Remove oil pump cover screws, and lift off cover.

(3)Remove pump rotors.

Fig. 5 Oil Pressure Relief Valve

(4) Wash all parts in a suitable solvent and inspect carefully for damage or wear (Fig. 6).

INSPECTION AND REPAIR

(1)Clean all parts thoroughly. Mating surface of the chain case cover (CCC) should be smooth. Replace pump cover if scratched or grooved.

(2)Lay a straightedge across the pump cover surface (Fig. 7). If a .076mm (.003 inch) feeler gauge can be inserted between cover and straight edge, cover should be replaced.

(3)Measure thickness and diameter of outer rotor. If outer rotor thickness measures 7.36mm (.3005 inch) or less (Fig. 8), or if the diameter is 79.78mm (3.141 inches) or less, replace outer rotor. For nichols rotors (8 lobes on inner rotor). If outer rotor thickness measures 7.64mm (0.0301 inch) or less (Fig. 8), or if the diameter is 79.95mm (3.148 inches) or less, replace outer rotor.

(4)If inner rotor measures 7.64mm (.301 inch) or less replace inner rotor, this specification applies to either rotor (Fig. 9).

Fig. 7 Checking Oil Pump Cover Flatness

(5)Slide outer rotor into CCC, press to one side with fingers and measure clearance between rotor and CCC (Fig. 10). If measurement is 3.9mm (0.015 inch) for the nichols rotor (8 lobe rotor), 5.6mm (.022 inch) or more, replace CCC only if outer rotor is in spec.

(6)Install inner rotor into CCC. If clearance between inner and outer rotors (Fig. 11) is .203mm (.008 inch) or more, replace both rotors.

(7)Place a straightedge across the face of the CCC, between bolt holes. If a feeler gauge of .102mm (.004 inch) or more can be inserted between rotors and the straightedge, replace pump assembly (Fig. 12). ONLY if rotors are in specs.

(8)Inspect oil pressure relief valve plunger for scoring and free operation in its bore. Small marks may be removed with 400-grit wet or dry sandpaper.

(9)The relief valve spring has a free length of approximately 49.5mm (1.95 inches) it should test between 19.5 and 20.5 pounds when compressed to 34mm (1-11/32 inches). Replace spring that fails to meet specifications (Fig. 5).

Fig. 9 Measuring Inner Rotor Thickness

(10) If oil pressure is low and pump is within specifications, inspect for worn engine bearings or other reasons for oil pressure loss.

OIL PUMP ASSEMBLY AND INSTALLATION

(1)Assemble pump, using new parts as required.

Pumps equipped with nichols rotors install the inner rotor with chamfer facing the oil pump cover.

(2)Tighten cover screws to 12 Nzm (105 in. lbs.).

(3)Prime oil pump before installation by filling rotor cavity with engine oil.

(4)Install chain case slowly refer to Timing Chain Cover Installation of this section.

Fig. 10 Measuring Outer Rotor Clearance in

Housing