Coolant disappearance

[Bill Taylor]

Doing my fall maintenance I discovered that all the coolant in the stbd pressure tank had disappeared. There is no sign of any green anti-freeze in or around the engine. The engine temp on warm-up for oil change was normal. I ran them in gear at 800 for 30 mins. With the engine cooled down I removed the rad cap to check and there was a slight “hiss” which indicated a pressure release. The exchanger itself does not have any raw H2O in it when I removed the anode. Over 125 hrs 700 nm trouble free this summer, Temp was always the same. Where oh where has the antifreeze gone. No excess engine smoke other than initial white at start up. Need help please. Regards Bill.

Topic

[Bill Taylor]

Mystery not solved, however things seem to be working. Pressurized the system to 15 psi empty and let it sit for 3 hrs. Pressure dropped to 13. Then filled the tank and re-pressurized the system for about 30 min. Pressure dropped to 12. Put on tank lid started her up, ran at 1500 until temp reached 180. No leaks nothing but normal. Cooled her down took off the cap level not changed. No smoke, just a smooth running 6BTA. Up shot is lots of coolant in reserve and a new pressurize tool. Just another boating day and another boat buck spent. Thanks again Rob for your help.

[Bill Taylor]

Rob: Thanks for your reply. Upon investigation everything is dry, expansion tank and recovery bottle. I have not removed that 5/16 sq fitting yet to see if there is anything in the block. As for checks, I did a cursory check the last time I checked the oil which was in Sept. and everything appeared normal. On that trip I ran at 2200 rpm for about 40 minutes and the temp was normal. Everything ran so well during the summer. No oil needed, no smoke. I ran at mostly at about 1800 which provided a comfortable ride given various weather and sea conditions. She just purred.
Yes I agree that 800 likely would not open the thermostat, but running in gear at the dock could be an issue stepping up to 1000.
I have another issue with my Cummins. Taking an oil sample when the engine is running. I have been unable to find a device or location of a port suitable for that task. Perhaps I should start another topic.
I am about to get a pressure test device before I refill the system. 20 ltrs is a lot of antifreeze to waste and to put into the water. Thanks again, any other suggestions welcome. Bill.

[Rob Schepis]

What was empty – the expansion tank or the recovery bottle?
It sounds like the expansion tank is what you were referring to..
Do you have recovery bottles? Are they empty too?
When was the last time that you checked the levels of both?
I doubt the 800rpm warm up was enough to get you too thermostat opening temperature.
Have you ever experienced an overheat on that engine?
Could be one of the exhaust manifold gaskets ….. manifold-cap or manifold-turbo.

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