Fresh water coolant loss when not running..?

Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
westerbeke w58
After running and engine cools down, I loose about a pint of coolant in overflow tank over night. This continues daily when not in use.
No sign of any water in oil, but I do notice (what I think is) a spert of coolant in exhaust at startup.
I’ve pressure tested coolant system. Cap is 14lbs so I went to 13lbs pressure. Pressure did drop to 9lbs and held over night. No external leaks noticed.
Attached pressure tester on cold engine removed heat exchanger zinc, pumped pressure and did get raw water leaking out of zinc installation hole - but I did notice leaking a bit without pressure..?hmmm
Next connected pressure tester on cold engine. Started engine and did not see immediate rise in pressure - until engine started to warm up. I think this indicates head gasket is okay. If head gasket leak I would think I’d have seen immediate pressure increase as soon as I started engine.
Might this be heat exchanger end cap gasket issue? Any other test suggestions?
Engine runs great, rapid starts, no oil consumption over entire season. If I use the boat continually as over the summer as we do, little to no loss of fluid.
I’m stumped - any ideas?
 
Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
F6729118-1425-4E92-B49F-2A9655088361.jpeg
50975A9E-DFBC-43F6-84C2-2A12B003D848.jpeg

I think I found the issue... some one messed up. One end cap had rubber washer / o-ring between the cap and gasket (correct) and the other had cap, gasket then washer. The washer wouldn’t allow the gasket to seal.
I’ll re do end caps and retest. It does look nice and clean...
Thanks for the replies!
 
May 17, 2004
5,031
Beneteau Oceanis 37 Havre de Grace
What kind of fluid did you see when you took the cap off? I might be wrong, but I thought the end cap kept the raw water from escaping, but I didn't think it touched the fresh water circuit. See http://www.pbase.com/mainecruising/heat_exchanger for more info. By all means reinstall the cap and see if it helped, but unfortunately I'm skeptical.
 
Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
From Main sail’s site...

How A HX Works
If you follow the arrows you can see that the HX is broken into quarters and is a four pass heat exchanger.

Raw water enters & then flows to the opposite end, returns to the inlet end, turns and heads back to the opposite end and finally turns back towards the inlet end and finally gets ejected into the wet exhaust system.

If you click on the picture to blow it up you’ll notice a chunk of an impeller blade that took up residence in this heat exchanger.




https://marinehowto.com/westerbeke-universal-marine-heat-exchanger-cleaning/
 
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Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
What kind of fluid did you see when you took the cap off? I might be wrong, but I thought the end cap kept the raw water from escaping, but I didn't think it touched the fresh water circuit. See http://www.pbase.com/mainecruising/heat_exchanger for more info. By all means reinstall the cap and see if it helped, but unfortunately I'm skeptical.
Correct the FW circuit has nothing to do with the end cap gaskets. End cap gaskets only keep raw water from leaking out, and allow access for cleaning the RW side.
 
Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
Davidsailor26 and Mainesail,
Thanks for reply - now I think I understand. The tubes are only for raw water passes and f/w coolant flows around the tubes for the heat exchange.
Now I pressure tested before the end cap gaskets and got this... (video)
Replaced end cap gaskets and no leak...? Not sure what is happening now - no bubbles or leaks in pressure.
Starting to think I should pressure test exhaust manifold also.... suggestions?
Thanks much
Bfree
 

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Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
Davidsailor26 and Mainesail,
Thanks for reply - now I think I understand. The tubes are only for raw water passes and f/w coolant flows around the tubes for the heat exchange.
Now I pressure tested before the end cap gaskets and got this... (video)
Replaced end cap gaskets and no leak...? Not sure what is happening now - no bubbles or leaks in pressure.
Starting to think I should pressure test exhaust manifold also.... suggestions?
Thanks much
Bfree
Couldn’t get video to upload screen shot of bubbles prior to end cap gasket replacement -
 

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Feb 25, 2018
23
Sabre 30 Long Island
Hi,
On some Westerbeke models, the original Exhaust Manifold circa 1986 were subject to a recall. Might be worth checking your engine, Hansen Marine could tell you.
 
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Tom J

.
Sep 30, 2008
2,301
Catalina 310 Quincy, MA
After running and engine cools down, I loose about a pint of coolant in overflow tank over night. This continues daily when not in use.
Does this mean you lose an additional pint each night, even if the engine hasn't run? Does the tank empty out? Do you add an additional pint each day?
 
Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
Does this mean you lose an additional pint each night, even if the engine hasn't run? Does the tank empty out? Do you add an additional pint each day?
I loose coolant after running engine. Seems to only be after running and engine cools down. I don’t loose any during running of engine or have any issue with coolant in oil. No overheating at all - all normal. I’m suspecting issue with exhaust manifold. This spring I’ll check coolant for exhaust gasses. Engine starts easy, good power, ..?
Thanks
 
Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
I loose coolant after running engine. Seems to only be after running and engine cools down. I don’t loose any during running of engine or have any issue with coolant in oil. No overheating at all - all normal. I’m suspecting issue with exhaust manifold. This spring I’ll check coolant for exhaust gasses. Engine starts easy, good power, ..?
Thanks
Yes, tank will empty out over a few days
 
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Mar 26, 2011
3,401
Corsair F-24 MK I Deale, MD
If you suspect the HE, you could leave it open overnight and see. Sometimes the tubes contract and leak when cold.
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
How do you know it’s going out the exhaust??? My guess is it’s going into the overflow tank, and not being sucked back, either due to a leaky tank/hose or a non-return cap. If you installed or pulled hoses on over flow tank maybe they are reversed.
 
Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
If it is leaking after shutdown then you have to be showing leak evidence somewhere.
Have you checked the coolant pump #49 in the attached?

A leak would be somewhere in this system.
Yes and all hoses, connections checked. Exchanger tested, engine inspected for leaks.
Will confirm there are no exhaust gas leaks (head gasket) in spring. Oil is fine....
I suspect exhaust manifold internal leak issue...
A spurt of coolant can be seen at cold start up ... no coolant loss while running though (12 hr runs many times)
 
Feb 3, 2012
71
Corbin 39 Pilothouse Cutter Lyme, CT
How do you know it’s going out the exhaust??? My guess is it’s going into the overflow tank, and not being sucked back, either due to a leaky tank/hose or a non-return cap. If you installed or pulled hoses on over flow tank maybe they are reversed.
The overflow tank level drops overnight about 1/2 pint during engine cool down. We can see slight pink coolant in exhaust at cold start - none after engine warms up or warm engine start. Tank and hose not leaking

Thanks
 
Jan 7, 2014
395
Beneteau 45F5 51551 Port Jefferson
Exhaust mainfold or the HX would be the likely source for AF in the exhaust. Do you have an engine heated hot water tank?Maybe that's not AF in the exhaust. How does your hot water smell?