Oil pump – removal, inspection and installation
1. Disconnect the cables from the negative terminals of the batteries (see Engine electrical systems).
2. Remove the gear housing cover (see Section Crankshaft front oil seal and gear housing cover – replacement).
3. Measure the backlash between the gears using a dial indicator. Install the dial indicator tip against one of the teeth on the idler gear and twist the idler gear back and forth (see illustration). This will give the backlash measurement between the crankshaft gear and the idler gear. Compare it to this Chapter’s Specifications.
11.3 With the dial indicator tip positioned against the idler gear, rotate the idler gear and compare its backlash to the Specifications
4. Place the dial indicator tip on the oil pump drive gear and check the backlash between it and the idler gear while securely holding the idler gear from moving (see illustration). If the backlash is greater than that listed in this Chapter’s Specifications for either gear, the gears must be replaced.
11.4 Check the backlash at the drive gear while holding the idler gear
5. Remove the four mounting bolts and remove the oil pump assembly from the gear case (see illustration).
11.5 Remove the four mounting bolts to remove the oil pump from the gear case
6. Remove the back plate of the oil pump assembly (see illustration). Clean the top of the gerotor planetary of oil and use a felt pen or paint to mark it with the word TOP.
11.6 Remove the two screws on the back plate, then mark the top of the gerotor planetary with a felt marker
7. Remove the components, clean them with solvent and dry them thoroughly. Assemble the components back in the oil pump housing. Note: The chamfer on the outside diameter of the gerotor planetary must face down, into the housing. Using a feeler gauge, measure the planetary-to-body clearance, the tip clearance and the gerotor-to-back plate clearance (see illustrations). If any clearance is beyond that listed in this Chapter’s Specifications, replace the oil pump assembly.
11.7a Measure the gerotor-to-planetary tip clearance with a feeler gauge
11.7b Measure the gerotor planetary-to- body clearance
11.7c Using the feeler gauge and a straightedge, measure the gerotor-to-back plate clearance
8. If the original pump is being reused, fill the pump cavity with engine oil and reinstall the back cover, then install the pump assembly in the gear case and tighten the mounting bolts to the torque listed in this Chapter’s, Specifications.
9. The remainder of installation is the reverse of removal. Refill the crankcase with oil, start the engine, and check for leaks and proper oil pressure.