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I've seen advertisements for Evans Waterless Coolant and have seen Jay Leno tout it on his YouTube channel. My question deals with the operation of the cooling system after you have properly introduced the coolant into the system.

Once converted, the system (as the name implies) will not have any water in it. The operating ranges of Evans is from -40°F to 375°F and won't boil or evaporate until the high end. Most engines run under 250°F. Considering this, the engine will never boil over under normal operating conditions. My questions are:

  • Could you run your cooling system with no pressure?
  • Would there even be pressure, considering the evaporation of water in a regular system is what causes the pressure in the first place?
  • What other benefits could come from running a waterless coolant? (This would be besides the obvious things like no corrosion or electrolysis.)
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Hmmm, about the benefits/drawbacks, I first wanted to complain that this stuff only has a heat capacity of 2.6J/(g * K), while water has 4.2J/(g * K). Water has an exceptionally high value, which makes it a great coolant, while other liquids are normally in the range below 2.4J/(g * K). However, water is usually mixed with anti-freeze, a 1:1 mixture has a value of 3.2J/(g * K). So your liquid isn't that much worse.

However, the liquid has a viscosity of 2000(mPa * s) at -40°C, while the standard 1:1 mixture has about 100(mPa * s), and pure anti-freeze has in the order of 1000(mPa * s). This means the stuff seems to be comparable with pure anti-freeze, though they don't state values for high temperature.

So, since the heat capacity is a little lower and the viscosity much higher, the performance of this product is not as good as of the standard mixture. But it's impossible to say how the performance actually is.

Besides lack of corrosion. I can't see a benefit. May be others can?

About the pressure:

Put some water into a closed, air-filled cavity, and heat it. When the temperature rises, more and more water evaporates, and the pressure rises exponentially. At 100°C, there's an overpressure of 1atm w.r.t ambient pressure in the cavity. At 120°C, it's already 2atm. If the cavity is opened now, the pressure expands, and since the water is hotter than 100°C, it will boil over. (physically speaking: The water wants to maintain the over pressure by evaporating as fast as it can)

For the mixture, the values are 0.9atm and 1.4atm, since the boiling point is higher (about 110-115°C)

This product has to be heated to 191°C / 375°F to generate a pressure of 1atm, so the pressure will be much much lower at typical motor temperatures.

Finally, a typical cooling system must be pressure tight to increase the boiling point, since motor temperatures can rise above the boiling point. But this is not necessary for this product. On the other side, the system is made pressure tight, some pressure will develop, but by far not as much as with standard mixture. And when you open the radiator of a very hot engine, the mixture will jump into your face, this product will not.


Comment: Are there any indirect benefits of not having pressure (or rather much reduced pressure) in the system? What about water/mixture's propensity for forming steam pockets at hot spots ... does this product alleviate this problem?

Hmm, steam pockets form when the temperature of the hot spot is higher than the boiling point at current pressure. The pressure in the cooling system is limited to about 2atm by a pressure relief valve, so the boiling point of the mixture is about 135°C / 275°F. The boiling point of the product is already much higher at ambient pressure, so steam pockets are less likely to form. If some pressure builds up in the system, the boiling point rises higher...

  • Are there any indirect benefits of not having pressure (or rather much reduced pressure) in the system? What about water/mixture's propensity for forming steam pockets at hot spots ... does this product alleviate this problem? – Pᴀᴜʟsᴛᴇʀ2 Dec 3 '16 at 16:54

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