Coolant Leak?

[mikefossl]

After an idle 3 months in the marina (engine thru hull closed), we noticed some (1/2 cup) coolant pooling in the engine bay tray and the overflow tank suddenly full when normally half full.

We started the engine and ran until warm. No obvious leaks.

Could this be simple condensation? We are in the Pacific Northwest and live on board. We heat during the day and not at night.

Thanks!

[Boatyarddog]

Hi, check the coolant tank cap for pressure and vacuum, no obvious leaks, but try to pressurize the system and watch the psi gauge for leakage.
Also, with regards to the tank being more full than you remember, with a small leak it's possible that your water heater (if equipped with one) can back siphon to the header tank.
Another possibility is the overflow tank may be closed loop and filled the low tank for you, normal for that type of system.
What engine is is?


Sent from SV Cloud Duster

[a64pilot]

Well I'm sure it isn't condensation, but Dog brings up a good point, the water heater has been pressurized, the engine coolant system has not, if there is a leak in the heat exchanger, overfilling the engine coolant would be logical.

I'd start with a pressure test, but de-pressurize the drinking water, as if it's pressurized, you may not show a leak.
I never thought about the water heater, good catch

[Stu Jackson]

Sounds, smells, leaks and electrical photos without wiring diagrams are almost impossible to diagnose over the internet.

There are a few basic troubleshooting issues, like check your hose clamps, that always apply, but specifics to your situation are daunting.

Good luck, trace the systems carefully. We had a small leak, changed hoses, did everything else, turned out it was a cracked HX bracket that had started a pin hole leak in the shell of the HX, underneath so we couldn't see it. Asking the kind of question you did here would not have helped me at all.

[mikefossl]

So with a leak in the hot water tank heat exchanger, I could be forcing fresh water into the engine cooling system.

That makes sense.

Does anyone know what is the nature of that heat exchanger? is it accessible? Repairable? It's a Isotherm hot water tank, maybe 15 years old.

I suppose in the interim I could isolate the cooling system from the heat exchanger with a couple of ball valves.