Hello all, As a result of a concern about tracking down a potential antifreeze leak (which I haven't done yet), I wanted to confirm the coolant type. There is no mention as to specific types either in my 3JH2E operating or service manuals. Yes, I could go (way) out of my way to get Yanmar branded coolant, but let's face it - it is not only way more expensive, its available almost exclusively at Yanmar dealers, and the nearest one to me is 15 miles away and isn't open on Saturdays or Sundays. And of course, what happens if you need more when you're out cruising?
In doing research, I found the following bulletin, published by Mack Boring: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=2ahUKEwizh_zu8Y3eAhWOy1MKHSFlD3cQFjADegQIBxAC&url=http%3A%2F%2Fldmarineservice.com%2Ffiles%2Fyanmar_bulletins.pdf&usg=AOvVaw3WK3R6vfJyTHOt5yGzFMDZ In the section about coolants, it recommends: Texaco Long Life Coolant, numbers 7991 and 7998. Unfortunately, one really can't find either product on the web, so I can't seem to find if it was orange (DEXCOOL) or red for diesels, or for that matter if it was ethylene glycol or propylene glycol based. Havoline Extended Life Anti-Freeze/Coolant, number 7994. Per this link, 7994 is DEX-COOL, but is ethylene glycol based. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwij_o2I843eAhWK0FMKHXc5AfMQFjAAegQICxAC&url=http%3A%2F%2Fwww.rialtainfo.com%2Fvw%2Fvw_images%2Fradiator_%26_coolant.pdf&usg=AOvVaw3ZxHApMqFHHgB-qcUwOYWa Dex-Cool Long Life Coolant, which at least at the time of introduction was propylene glycol based and is Organic Acid Technology (OAT) thus meaning less toxic. Funny thing is, Dex-Cool was not even introduced until a year after my boat was built (1995) and at the time, was only being used in GM cars. Prestone Extended Life Coolant, product code AF888. Per the attached, guess what, it's Dex-Cool. https://www.autozone.com/antifreeze-radiator-additives-and-windshield-wash-fluid/antifreeze/prestone-antifreeze-engine-coolant/87934_0_0. It is ethylene glycol based, but Prestone says it is OAT, which would seem to conflict with what I can find about traditional Dex-Cool. Not entirely satisfied, I wanted to see what a Yanmar official publication recommended. In a 2009 JH Series Operation Manual, it recommends Texaco 7997 and 7998 (same as above). It also recommends Havoline 7994, as above. It however says nothing about Dex-Cool or Prestone AF888. I get similar results in a 3JH4E manual. Then, of course, I was faced with the fact that while I used Prestone AF888 when I flushed and replaced my coolant, I was replacing what appeared to be traditional green coolant (presumably old-style ethylene glycol). I only now read a lot of horror stories of replacing green with orange Dex-Cool, saying that one can never flush out the system sufficiently to keep the orange coolant from gelling to the point the engine overheats. So, at this point I have no real idea what to thing other than the Prestone AF888 I used should be OK as long as it doesn't a). Turn color B) Gel up and c) My engine temperature stays OK. Sigh... Does anyone else here have anything more authoritative? Bruce Whitmore 1994 C&C 37/40+ "Astralis" (847) 404-5092 (mobile) bwhitm...@sbcglobal.net
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