Yanmar Diesel Engine Question

[Joe Dickson]

I recently purchased a 1984 Hunter 31 and I'm still learning my way around this engine. I have been told that my water temperature sensor has come loose. It has a black wire with what looks like a very small black spark plug cap at the end. There is a brass probe that protrudes from that which appears to have been attached to the front of the engine with what looks like a green epoxy. Is this serious? Is the repair simply a matter of re-attaching the sensor to the engine? If so, with what should I re-attach it to the engine?

 

[Jim Logan]

Sounds like its broken

From your description, it sounds like the wire connection to your temperature sensor connector is actually broken. On most Yanmar temp sensors, the wire from the harness just pushes on with a normal connector. If the black wire will not just push back on and click in place, its probably broken. My advise is either get a mechanic to look at it, or go buy the yanmar book for the engine you have and look at the pictures and learn how to take care of the engine yourself. If I just bought this boat, I would make sure that the temp sensor is working, as overheating is a common problem on older boats due to the buildup of coke in the exhaust manifold and crud in the water channels. One way to keep the temp indicator from indicating overheat is to disconnect the wire (not that I'm saying that is what the former owner of your boat did, but it could happen), so you need to make sure your temp sensor is working and that your motor is not overheating.

 

[Bob Rutland]

Replace It !

Ours did the same thing. Go ahead and replace the whole sending unit. It's not hard to replace and well worth the effort. Good Luck, Bob