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Old 08-15-2014, 12:22 AM   #20
Marin
Scraping Paint
 
City: -
Join Date: Oct 2007
Posts: 13,745
Quote:
Originally Posted by Mule View Post
The surveyor ask, "are you ever going to have this boat in freezing temperatures? If not, drain the antifreeze, replace with water and add a rust inhibitor. Water is a much better medium to promote engine cooling than antifreeze."

Comments.....after busting my Marvel Mystery Oil myth I figgered I best air this one out too....
I think that is pretty bad advice. Coolant, particularly diesel coolant, contains components that combat corrosion and other issues that can arise inside an engine. They are formulated to resist the cavitation that FF speaks of, for example.

If water with a rust preventative was all that was needed, then everybody would be using it and the engine manufactures would be including it in their operators manuals. I have yet to see an operators manual--- be it for my 1970s Land Rover to our new Ford F-150 and everything in between including vehicles from Austin-Healey, BMW, VW (diesel), Land Rover, Ford, Aston Martin, and Subaru--- that talked about using water and an anti-rust additive. Some of these vehicles-- like the new Ford and our Range Rover-- have aluminum engines, so the coolant has to be compatible with that material.

Most of the ratios that have been specced for the engines in all our vehicles and coolant-cooled boats have been 50:50 for our climate.

When we bought our current cruising boat the previous owner had put Sierra non-toxic anti-freeze in the FL120s, I think because the manual for the new hot water heater that he'd just had installed called for it (coolant from the starboard engine circulates through the hot water heater to heat the water).

Immediately after taking delivery of the boat, I asked people we know in the marine diesel manufacturing industry what we should be using for oil, coolant, etc. When I mentioned the Sierra coolant that was currently in the engines, one of the most knowledgeable and experience of these folks said, "Get that sh*t out of the engines NOW."

The coolant that was universally recommended by the industry people we talked to was Cat diesel coolant. Cat doesn't make it, of course, but it's made to their specifications, and it contains all the anti-corrosion and other characteristics that are what should be in a diesel engine's cooling system

So that's what we did, and we've been running Cat coolant ever since. Again, it's a 50:50 mix, which is what's called for in our climate.

I'm not saying that Cat is the only brand that should be used. There are plenty of others, I'm sure. But it's important to use a coolant that is specifically formulated to provide the cooling and combat the problems that can occur in a diesel's cooling system.
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