trouble shooting oil pressure 2003 50 HP 4 stroke Merc outboard?

1st,filter because its cheap,2nd oil in case its diluted with fuel,3rd if its got an oil cooler make sure thats clear.find out if its got an oil themostat fitted,cause if that has failed in closed position, oil will over heat,thin out and lose pressure.lastly borrow,buy an oil pressure gauge screw in where buzzer is fitted,to see if engine has oil pressure,at cold, hot,idle and load.if you have a reasonable pressure,it must be switch.if not,oil pump,big ends or main bearings are worn

glen
October 2008