Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 357Get this manual
5Install vent tube (a) thru hole in oil pump cover plate (b) 4Remove gasket (a)
6Install main body assemblySee pagei' 15
5Remove check valve springs (a)
Oil Pump Outlet Check Valve Removal
1Remove main body assemblySee page 152Remove internal oil filterSee page 173Remove two screws and lockwashers (a)Then remove oil pump cover plate (b)