Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 136Get this manual
Oil Pump Assembly 1Reassemble the oil pump assembly2Lubricate the outer and inner rotors thoroughly with engine oile a
2Place O-ring on oil pump3Align the slot in the oil pump shaft with the camshaft projection4Fasten with boltsTorque to specification
Oil Pump Housing Outer Rotor Inner Rotor Shaft O-Ring (2) O-Ring (1) Cover Screw (2) -