Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 229Get this manual
"Down" Pressure Check 1Tilt engine to full "Up" position, and engage tilt lock leverSlowly remove fill screw to bleed pressure from reservoirFrom full closed (clockwise) position, turn manual release valve to turns (counterclockwise) to bleed remaining pressure from Power Trim systemRemove allen plug (a) and connect test gauge as shown
2Install components, as shown
Test Gauge Assembly Valve Valve Adaptor Fitting (22-11243) Hose (Route Hose so that it Will Not be Pinched When Engine is TrimmedDown")Hose (Not Used for This Check)