Mariner 75hp 2stroke 2005

[Jimhar]

Discovered water in 2 stroke tank and oil pump blocked. Have now gained a knocking sound from engine. Compression test was all ok, have removed from boat to investigate has anybody got any tips of where to start looking for faults.

 

[CalicoJack]

There are probably better ideas but..... mix up some 50 :1 two stroke mix in the fuel tank and run the engine on that, in a tank or off a hose. Then starting at the oil tank clean and refresh with oil. Trace the oil pipe and disconnect at every joint/union making sure that oil is flowing and that it’s fresh oil. When you are certain you have fresh oil going into the combustion chambers, go back to straight petrol in the fuel tank. Beware if you are running an engine under light load and very few revs they use tiny quantities of oil, so watching the oil tank level can be very frustrating.