1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 221Get this manual
Draining and Inspecting Gear Lubricant If gear housing is installed on outboard, disconnect (and isolate) spark plug leads from spark plugs before working near the propeller1With gear housing in normal running position, place clean pan under housing and remove vent plug and filldrain plug (with gaskets)
Propeller Removal
If gear housing is not before attempting to propeller, remove (and from spark plugs to starting1
removed from outboard, remove or install the isolate) spark plug leads prevent outboard from
Bend tabs of tab washer away from nut
aVent PlugWasherFillDrain PlugWasherTab WasherNut
51119Inspect gear lubricant for metal particles (lubricant will have "metal flake" appearance)Presence of fine metal particles (resembling powder) on the drain plug magnet indicates normal wearMetal chips on the magnet indicate the need for gear housing disassembly and component inspectionNote color of gear lubricantWhite or cream color indicates presence of waterGear lubricant drained from gear case assembled with Special Lubricant 101 or gear case recently in operation will have yellowish color due to lubricant agitationaerationThis is normal and should not be confused with the presence of waterPresence of water indicates the need for disassembly and inspection of oil seals, o-rings, gaskets and components for damage