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I thought about it for my V8 Land Rover a couple of years back, as did several of my mates, after much discussion/debate around the local club. Some decided to try it (I didn't), and
all are now back on standard coolants!
Firstly, I'd be very wary of the sales hype around these "waterless" coolants. They have a much lower specific heat capacity than pure water, and transfer heat away from its source less efficiently. Water is, without question, the most efficient liquid at conducting heat for a minimal rise in temperature. Yes, it doesn't work below 0C, and you'd have to add a pump lubricant/corrosion inhibitor if you were running it neat, but it is best at what it does.
The biggest drawback of water is its relatively narrow operating range (0-100C). Pressurising cooling systems can expand this range by another 15C at the top end without effecting heat transfer. Adding ethylene glycol, propylene glycol or any other substance widens it operating range, but at the expensive of thermal conductivity. Just adding one part ethylene glycol coolant to one part water (50/50 mix) reduces its specific heat capacity (cooling efficiency) by about 20%, propylene based products are even worse. Evans is even less efficient at thermal transfer than the above commonly available coolants.
The only thing Evans (or similar) does is to widen the operating range (it boils at close to 180C). Who'd want there engine to run at temperatures anything like that? There would have to be something already very wrong!
A well-maintained, normally operating engine with a modern high pressure cooling system and aluminium radiator (like an XT) is designed to run between 90C and 105C for peak efficiency, which is perfectly within the bounds of water's capabilities. And at these sort of temperatures water is 20% more efficient than anything else out there at removing heat.
Waterless coolants might just make sense if you've got a poorly maintained cooling system/engine that is prone to boiling. Even an engine prone to a bit of overheating would be better of with a water based coolant, as it would be more efficient and run cooler. In fact a waterless coolant would probably make the overheating issue worse?
Those who tried it found that their engines ran hotter with waterless coolants (a sign that it is less efficient). Two, had cylinder head gasket failure, which they put down to the constant running at higher than normal temperatures.
Also bear in mind that the procedure to change to something like Evans is very expensive. The whole system needs to be flushed (twice) with hydroscopic fluid to purge any water out (Evans fails if contaminated with even the tiniest amount of water). That in itself costs about �20 per flush, then there's the cost of the Evans itself, which ain't cheap!
Probably the worst thing about it is, if you loose some coolant out on the trail, or have to make an emergency repair, you won't be able to, because you can't just top it up out of your hydration pack or water bottle! To protect yourself in the wilderness, you'd have to lug around a bottle of Evans everywhere you went.
Just running 100% glycol coolant would achieve very similar effects as using Evans, for less money, and you wouldn't have to flush anything, and you'd be able to do an emergency top-up with good old H20!
Last edited by Pleiades; 13-02-14 at 18:55. Reason: typoos!
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13-02-14, 11:15
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