Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 386Get this manual
Oil Pump Outlet Check Valve Installation 1Install check valves (a)NOTE: a-rings on check valves are not replaceableIf a-rings show signs of deterioration such as swelling, cracking or discoloration, replace check valve
3Install gasket (a)
4Install screws with lock washers (a) and oil pump cover plate (b)Torque screws to 18 lbin(1 .98 Nm)