Coolant concerns

[Luvboats]

Howdy all,

A dockmate of mine recently approached me with an issue regarding his domestic water and engine coolant. He filled his bilge with a mixture of engine coolant and the vast majority of his freshwater tank. He noticed his bilge pumps running rather frequently along with his freshwater pressure pump and when he opened the engine bay saw water pouring out from the overflow tank connected to the heat exchanger cap. He couldn’t understand how until I explained to him the way the domestic water heater uses the engines coolant water to heat fresh water. Clearly he has a leak in a heat exchanger tube which is letting the fresh water infiltrate the engine side of the water heater and then overfilling engine until it overflows. He has ordered a new water heater and he is all good.

My question:

Do you think the use of a non-toxic coolant is warranted in case the infiltration should be opposite of what I described above and the coolant somehow makes it into the freshwater side? Especially for those that drink the water from their tanks? I realize the domestic water side should be a higher pressure than the engine side but what if I turn my freshwater pump off, as I frequently do? If I have a foot or hand pump which “sucks” water from the tank do I have an increased likelihood of drawing up coolant if my water heater fails as in the above case? Am I worrying about something that is more rare than a two headed unicorn on Mars and thus should focus on more legitimate concerns on my boat?

Thoughts, ideas, concerns, comments, and ridicule are wanted and welcomed,
~Jeb

[Lepke]

If it makes you sleep better, then yes. Otherwise, no.

[Manateeman]

There was a recent case of the USCG rescue of a woman who was poisoned by a leak into drinking water by antifreeze...off California.
Maybe other posters could provide the details.
Some Antifreeze is very toxic.
Captain Mark

[CarlF]

Non-toxic antifreeze (propylene glycol) is intended to keep domestic water systems from freezing in winter - not for use in an engine. It does not transfer heat nearly as well as engine coolants. Your engine will likely overheat and any warranty you might have on the engine will be voided.

[Luvboats]

Carl,

You of course are correct regarding the non toxic antifreeze. I should have been more clear as to what I was talking about. I should have said less toxic or low toxicity varietals of engine antifreeze similar to these pictured. Your post inspired me to do a little reading and it appears that these less toxic coolants, which most manufacturers have a version of, are made with PG (propylene glycol) instead of the traditional EG(ethylene glycol). Not sure if they are a mixture of the two or what magic they have performed to make them less toxic as a chemist I certainly am not nor plan to be. Two examples I found are advertised as low or less toxic but a few, like the starbrite brand pictured, list them as non-toxic and designed for engine use. I wonder if the less efficient heat transfer you describe with the PG will cause any concerns to my Yanmar 3gm’s? Your concern regarding warranty is very valid but in my case they are over 20 years old so my warranty has long since evaporated.

Manateeman,

Yes I recall that story but I am unable to find details as to how the antifreeze ingestion occurred. It would be interesting to learn the particulars of that case.

Thanks for the responses thus far.

~Jeb