Please identify this wire

[Bollie]

1963 40Hp Evinrude BigTwin. There is a wire coming out of a rubber plug on the front of the head of the lower cylinder It looks like a sensor of some sort, it a little lose, how can i test to see if it is working at all. I disconnect it but could not detect a difference while the motor was idling

 

[OBJ]

Re: Please identify this wire

That's the overheat sensor Bollie. Won't do anything to the engine running. It's supposed to either light a light on the dash or cause an alarm horn to sound if the engine overheats. Take the other end of the lead, the one that goes to the harness, and ground it with the key in the "ON" position. Should lite a light or cause the warning horn to sound.

 

[Bollie]

Re: Please identify this wire

Thank you for info the you guys are great.

 

[mikeyzx2]

Re: Please identify this wire

OBJ, my motor has one sensor installed in one head, and the other wire does not have a sensor at all, although the other head has the port to install it in. The book says not all models have both sensors, but is it a good idea to have both sensors instead of just one?