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post #1 of 6 Old 09-13-2011 Thread Starter
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Yanmar losing coolant

Here is what I know:

Engine is a 14 year old Yanmar 4JH2E with 2000 hrs.

- Earlier in the season the engine would use a few ounces of coolant when I ran it about an hour or 2
- Now suddenly the coolant is disappearing at the rate of appr 64 ounces per hour
- No sign of coolant in the oil.
- No sign of oil in the coolant.
- No sign of coolant in the bilges or under the engine.
- Engine otherwise runs perfectly. Good power and smooth operation. Starts on first try.

Last night I performed some diagnostics with a pressure tester. Here are the results:
- Engine off, system pressurized to 16lbs, tester slowly lost pressure. Started the engine and AF came out the exhaust. Took a few tries to start.

- Refilled system, connected tester, started engine. No jump on the tester. If the gauge suddenly jumped up it could indicate a head gasket problem.

- Engine running, pressurized the system to 16lbs and needle did not jump around. If it did it could indicate cracked head or block. System slowly lost pressure.

I am thinking bad heat exchanger. I will pull it tonight to check.

Tim R.
Our Carina is for sale
1997 Caliber 40LRC

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Last edited by Tim R.; 09-13-2011 at 01:35 PM.
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post #2 of 6 Old 09-13-2011
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"System slowly lost pressure", Possibly coolant leaking into the raw water side of the heat exchanger? Or small leak in the head gasket?

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post #3 of 6 Old 09-13-2011
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Heat exchanger would be my guess also.
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post #4 of 6 Old 09-14-2011
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Originally Posted by JimsCAL View Post
Heat exchanger would be my guess also.

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post #5 of 6 Old 07-01-2013
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Re: Yanmar losing coolant

whatever happened on your heat exchanger? I'm having some weird issues and suspect the HE so was searching the threads and found this one.
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post #6 of 6 Old 07-02-2013
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Re: Yanmar losing coolant

My vote is to replace heat exchanger .Make sure the sacrificial zincs in it are good and maintained.
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