Wrong Coolant

[Bryan Dougherty]

While having my oil changed in Key West, tech also offered to change the coolant in my Yanmar 6LY3-UTP (in ’09 mainship 34T).  I usually have all supplies on hand so I know what we’re using but I only had 1 gallon of ELC coolant and he said no problem he’d bring what’s needed.

I return back to the boat this week to find the left over/extra coolant used was Peak Fleet Charge SCA Precharged…it says good for all Heavy Duty Diesel.  I called him as I’ve read the manual and posts that the Yanmar’s should have the Texaco or Havoline…he said they use the Fleet charge all the time in Yammar’s and it protects against liner cavitation, which is the issue Yanmar is guarding against.  

So…I’m a follow the manual guy…how big a problem is this?  or not at all?  I’ve got 20 hrs of running until the boats back in its winter home and I could get it changed easily or is this something I need to address right away or is he right and not at all.

Thanks in advance.

Bryan

Topic

[Bryan Dougherty]

Thanks…

Rob and Dave,

Thanks for the response/advise…I’m going to change this coolant out for the Dex-Cool when I get the boat back to North Palm Beach this weekend. As careful as I’ve been on all service items for this engine its not worth the risk to keep it.

Cheers

Bryan

[David Marchand]

Knowing the right coolant to use on a Yanmar is difficult, because Yanmar’s recommendations were written twenty years ago and referenced specific brands that were available in Asia at that time and are not available in the US or have since gone out of business.

So a bit of history:

At about that time GM developed their Dex-Cool forumulation to deal with aluminum exhaust manifold cavitation and licensed it to others. The two manufacturers that Yanmar recommends use the Dex-Cool forumulation. So a good assumption is that any antifreeze that says Dex-Cool is ok and these are available at your local auto parts or big box store.

Now what about the Peak stuff. I looked it up and it does not say Dex-Cool but it does say low silicates, so it probably is not based on the GM Dex-Cool license. Silicates were the source of the cavitation problem.

So my guess is that you are probably ok, but to be totally safe, drain and replace with Dex-Cool stuff.

David

[Rob Schepis]

If there was ever a time I went 100% by the book it was maintaining the coolant when I owned a Yanmar 6LP.  I’m with you, what they use “all the time” means nothing.  I’m a little out of the Yanmar loop but I believe they call for “silicate-free”, not “low-silicate”, like the tech used.

[Author]

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