1985 Mercury Outboard V-300 V-3.4L Shop Service Manual, Page 200Get this manual
HYDRAULIC SYSTEM TROUBLESHOOTING GENERAL CHECKS
IMPORT ANT: Operate Power Trim system aUer each check to ee It problem has been corrected If problem has not been corrected proceed to next checkICheck thai manual release valve knob is tight cnd right (clockwise) position10
2Check trim pump oil level nd fill if necessaryRefer toFil ling nd Bleeding th Power Tri Syste m", See Index3Check for eX ler nal leaks in Power Trim syste mTight en fitting( s) or replace defective part(s) if leak is fo und 4Check for air in Power Trim sys tem and bleed if necessaryRefer toFill ing and Bleeding the Powe Trim System"See !ndu
AWARNING
Belore loosening the manual releasvalve
knobmake surall persons are clear of engine as engine will drop to lulldown" position when valve Is looened5Re mo ve the manual release valveInspect the vah'e Ind" rings fo damageReplace the manual release valve if the valve or "0" rings are damagedIMPORTANT: Two dilierent styles 01 manual release valves are usedtwo0" ring type and three" ring typeThey cannot be InterchangedThree" Ring Type Manual Release Valve