86 Cat 30 Universal M-25 Overheating Issues

[Mark Magee]

Catalina Sailors,I have read the archives on the issue of an undersized (2") heat exchanger installed in my vintage (1986) Cat-30. I have the overheating problem above 24 to 25 hundred RPM. Anything higher and an overheat happens within 15 minutes.I have a very good friend who is a professional pleasure boat diesel mechanic who assured that -everything- with system is fine, except the possibility of a stuck thermostat not opening completely.Question. Has anyone here in the South, where water temps are WARM, summer over 88 F, done the 2" to 3" heat exchanger swapout to have an overheating situation similar to mine resolved?Any and all feedback appreciated.RegardsMark MageeCat-30

 

[JEFF MOSER]

Had similar problem

I had a similar problem on my M25. However, what I did was a little different then you are proposing. I removed the heat exchanger and soaked it in a bath of decalcifier. (I used the stuff that is used to decalcify coffee pots bought at any grocery store). I then shook out all the loose calcium and soaked again. You can also have it steamed cleaned. Next replace the temperature sensor at you thermostat. They sometimes go bad.My engine was consistently overheating at 3100 RPM. Now since doing this I have experienced no overheating.TRY IT IT MAY BE CHEAPER THEN BUYING A NEW ONE.