1998 Mercury 9.9/15HP 4-stroke outboards factory service manual, Page 225Get this manual
OIL PUMP
CleaningInspectionRepair
1Inspect oil pump components for pittingscratchesReplace if necessary
2Using feeler gauge, measure the following oil pump clearancesReplace if worn or out of specification Between outer rotor and pump housingBetween the inner rotor and outer rotorBetween the outer rotor and pump housing