Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 294Get this manual
Hydraulic Repair .Q,.CAUTION
Work area must be dirt-and-lInt-'ree The slightest amount 01 dirt In hydraulic system can cause pump malfunction
Manual Release Valve Replacement
NOTE: Replacement of manual release valve can be completed without removing the trim pump from boat
.Q,.WARNING
Belore loosening the manual release valve knob make sure all persons are clear of engine as engine will drop to lull "Down" position when valve Is loosenedIMPORTANT: Two different slyles of manual release valves are used: two" ring type, and three" ring typeThey cannot be Interchanged
Turn manual release valve counterclockwise to removeTo install new valve, turn valve clockwise until it