1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 191Get this manual
Hydraulic System Troubleshooting Support outboard with tilt lock pin when servicing power trim systemIMPORTANT: After debris or failed components have been found (during troubleshooting procedure) it is recommended that unit be disassembled completely and ALL O-rings be replacedCheck ball valve components and castings must be cleaned using engine cleaner and compressed air or replaced prior to re-assemblyIMPORTANT: Power trim system is pressurizedOutboard must be in the full "UP" position (trim rod fully extended) prior to filldrain plug, or manual release valve removal
Follow preliminary checks before proceeding to troubleshooting flow diagrams (following)
Preliminary Checks
IMPORTANT: Operate Power Trim system after each check to see if problem has been correctedIf problem has not been corrected proceed to next check