Engine alarm sticks

[Bob]

My engine alarm seems to be sticking after the engine starts, especially when I start the engine the second time after coming in from sailing. It will stop after several minutes. There is plenty of oil, compression, coolant etc. engine has only 300 hrs and runs great. It was professionally re-powered before I bought the boat last year(1990 Catalina 28) with a MD25. I had a full engine survey done and it passed with flying colors. I believe the alarm problem is a short? Is anyone out there having the same problem? Thanks BOB

 

[John Tesoriero]

My guess

I had a similar problem with an older Yanmar diesel. It turned out to be the temperature sending unit. It was sticking open (electrically closed) when the engine was shut off. I guess that when the engine was shut off, the cooling water in the hot engine reached the set temperature for the unit and tripped the alarm. My alarm would also stop after a bit - when the engine cooled down. Changing the sending unit cured the problem.