Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 232Get this manual
Pilot Check Valve Reassembly 1lubricate a-rings with power trim fluid2Install one of the seats into manifoldPush the seat into place using 932" or mm socket on the OUTSIDE diameter of the seat3Inslali corresponding poppet, spring and plug4From the opposite side of the manifold, install
Oil Pump Reassembly
1Install the down relief ball and spring into manifold2Check to see that O-Rings are placed on bottom of pump3Place O-Ring (square cut) on filter4Place filter over the oil pump
spool and the other seatPush the seat into place using 932" or mm socket on OUTSIDE diameter of seat5Install remaining poppetspring and plugTorque plugs to 120 lbin(13.5 Nm)