Troublesome coolant leak on Universal M320??

Posted by comfortablydumb2@reddit | sailing | View on Reddit | 4 comments

I’m in the process of purchasing a 1993 Catalina 28 with aforementioned engine. The seller is extremely knowledgeable with Catalina boats and this type of engine.

A while back he noticed that the coolant reservoir was low so he started to diagnose the problem. He doesn’t want to sell me a boat with an engine problem.

There are no visible leaks anywhere, compression test was fine, cooling system has been “burped”, analysis on oil shows no contamination.

The next step is to scope the “exhaust manifold and elbow”

The seller is kind of at his wits end and so am I as I was wanting to get this deal wrapped up before winter.

Any other input that can be offered??

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whyrumalwaysgone@reddit

Best case: heat exchanger has a pinhole leak in the tubes. The coolant side is high pressure when the engine is hot, so if there's a pinhole it leaks into the water of the exhaust unseen. Fairly common, especially if the owner hasn't kept up on zincs. A new heat exchanger is $400-$600 last I checked.

Worst case: cracked head and coolant is escaping that way. This is less common, but depending on where the leak is you may see white smoke in the exhaust and/or power loss

comfortablydumb2@reddit (OP)

Thanks for the reply. I’ll run this past the owner. However, it is a fresh water boat, it wouldn’t have zincs would it?

There is no white smoke or power loss.

AkumaBengoshi@reddit

A freshwater boat should still have anodes, but usually magnesium or aluminum instead of zinc

Effective_Store_9083@reddit

Bad heat exchanger