Universal M25 Heat Exchanger

[Mike Davis]

I have a Universal M25 engine on my CD31. The heat exchanger is right above the Hurth transmission, which makes it very difficult to open up the dipstick to check the level of the transmission fluid. It is also difficult to change the pencil zinc on the heat exchanger. When I get out of the engine compartment, I feel that my body has been contorted.
Has anyone ever moved the heat exchanger to a different location? My first thought would be to mount it on the ceiling of the engine compartment and replace the hoses of the exchanger with longer hoses. Any thoughts would be appreciated. Thank you,
Mike Davis

[Jim Walsh]

Steve Laume did exactly that on his CD30. Perhaps he will chime in with some tips based on his experience. It is a perfectly feasible solution to your predicament.

[Capt Hook]

I just replaced the HX on my CD 31. Not sure exactly what you mean by when you get out of the engine compartment but I found it easier to get at the HX from the cabin leaning over the engine than to approach it through the sail locker. I was concerned about getting contorted going through the sail locker.

The PO gave me a tip. Leave the two hoses that connect to outlets at the bottom of the HX connected and disconnect them where the connect to pumps on the front of the engine. The two top hoses are easy to reach by leaning over the engine. Then you can remove the HX fairly easily.

[Steve Laume]

I did move the heat exchanger on Raven. Same set up, same problems as you are having. I made up a bracket and moved it aft of the engine. I can now access the dip stick and the zinc without removing the heat exchanger. I might have been able to find a more convenient location but this was very easy. The one thing you need to consider when relocating is that it doesn't get higher than your expansion tank.

They did put that thing in a really stupid place, Steve.

[jerzyjoe]

I have a 1985 cd31 with what I believe to be the original heat exchanger. It works fine-engine never goes above 140. My problem is with the zinc, more specifically, the plug to which the zinc attaches. I cannot get the plug to thread properly. Is it possible that the plug on the original is an nps thread (straight) rather than npt which is tapered? If not that, it’s been cross threaded.

Thank you
Joe