Separate the cover from the body.
Remove the drive shaft and the drive gear of the oil pump.
Wash the pump body with gasoline.
If the oil pump parts are heavily contaminated, remove the oil receiver, take out the oil receiver mesh filter and clean it.
Check the gap between the gear teeth, which should be 0.05 mm (maximum permissible 0.20 mm), and the gap between the outer diameter of the gears and the bore of the oil pump housing, which should be 0.15 mm.
Measuring the clearance between the gear teeth and the clearance between the outer diameter of the gear and the bore of the oil pump housing
Assemble the oil pump in the reverse order of disassembly.