1993 Mercury 50 oil alarm

[hevysrf]

My son was on the boat yesterday, Said the alarm went off. Cooling stream is strong. Disconnected banana plug to oil tank and alarm stopped. Tank is more than half full. Am I correct when I say that the alarm only detects oil level, not flow or pump rotation? When the tank is half full I should read open circuit thru sensor, and when almost empty circuit should be made? Thanks Marty D

 

[Jake_MN]

Re: 1993 Mercury 50 oil alarm

I believe on your motor (I have a 92 40 hp that should be the same configuration) there are two oil alarm senders. One is at the tank, the other at the pump. If disconnecting the alarm wire at the tank stops the alarm, then I'd suspect that the float in the oil tank has deteriorated. It's a common occurrence and happened in my motor as well. If you want to be sure, mix a gallon or two of gas and pre-mix it at 50:1. Then mark the level of oil in the tank. Run the engine above idle until the pre-mix is gone and check the oil level again. If it has dropped, you have a tank-sensor issue and need to either replace the sensor or disconnect the tank alarm and be vigilant about the level.