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post #15 of Old 04-19-2012
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Re: Rebuilding Yanmar 3GM30F; need advise $?

Originally Posted by Beersmith View Post
enjoying this thread.

I will be doing the same thing with my Yanmar 4JH2E. Only 1,000 hours, but sat idle for 10 years and overheated pretty bad by running without water flow for about 20 minutes.

It took me around FL (through the Okeechobee Waterway) without any real problems. The problems were easy to identify: bad mounts, hoses need replacements, very dirty fuel tank; but nothing serious. No smoke or anything out of the exhaust.

My biggest worry is what may have happened when it ran hot. The engine is currently pulled, so I'm unsure how I would get it tested.
If there was coolant in the engine after the 20 minutes even if it was boiling, then almost certain there was no damage. Was there any coolant after you let the engine get cold?

If the coolant was gone, and the head is made of aluminum, there will almost always be cracks. A machine shop that specializes in welding of engine heads should have a look at it. Test the head for cracks. Almost always these cracks can be repaired, but the welder has to know what he is doing.

Cast iron can take a lot of abuse. Probably no cracks if coolant was boiled out of it, but need to check the head for cracks. Harder to weld and sometimes a new head is needed, cannot be repaired. Was the paint burned off the head?

Last edited by LakeSuperiorGeezer; 04-19-2012 at 06:28 PM.
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