Recip Technology: Waterless Engine Coolants

A look at the technology and SAIB NE-05-84R1

According to Light, tests have shown that when Evans waterless coolant is forced to operate at a temperature considerably hotter than conventional coolant temperatures, engine metal temperatures remain under control and engines are safe from detonation. Evans is up against the problem that water-based coolants have been the industry standard for more than a century. Waterless coolant is comparatively expensive because it is a proprietary product and because it is not diluted for use. However, waterless coolants provide advantages that are unavailable to water-based products and the payback period is short.

High costs for fuel and environmental concerns have focused attention on fuel economy. Tests have demonstrated that using a waterless coolant results in a significant fuel economy improvement for heavy-duty diesel engines, and by reducing fuel consumption you decrease emissions, which results in a cleaner environment. You also reduce the cost of transporting goods from coast to coast, thus making basic items like bread and milk cheaper to buy.

There is another added benefit to engine owner, operators, and maintenance technicians. Evans NPG Coolant contains ethylene glycol and also an enzyme inhibitor that acts to prevent ethylene glycol poisoning, so it is less toxic than traditional coolants. It is also a “fill and forget” fluid that is good for the life of the engine. The only time you would have to replenish the coolant is if it became contaminated with water. Sounds too good to be true?

I asked Tourville about the downside to using Evans waterless coolant, which could be the initial price point, depending on your idea of coolant cost. The highest priced Evans coolant lists for about $43.00 a gallon. But, as I am a former aviation maintenance type, that did not sound like a bunch of money for what you get. We AMTs know that aviation quality parts, tools, bits and pieces, and replenishment fluids are all expensive.

Advantages to owners and operators
The primary advantages to owners and operators are lower operating cost, and engine utility and reliability. These benefits can be gained through:

  • Avoiding boil-overs
  • Higher gasoline efficiency
  • Reduced emissions
  • Higher compression and power
  • Knock reduction
  • Improved octane tolerance (lower octane fuel usable)
  • Reduction of hot spots (critical metal temperatures)

The primary advantages to OEMs are “fewer design limitations and weight reduction, including improved stability of engine operating temperatures, and improved aerodynamic styling. The radiator no longer needs to be higher than the engine and can be placed anywhere. Also, weight reduction is possible if higher coolant temperatures are used. Smaller radiators mean less coolant, plus the use of light-weight metals (Evans has a coolant compatible with magnesium for engines), and small cooling jackets in the engine, smaller fans.

In addition, these coolants offer faster combustion chamber metal surface warm-up, CO reduced in start-up (liners get hot faster) mostly because of the lower specific heat of waterless coolant. Finally there is the elimination of premature spark plug failure and head cracking by better cooling of head.

The primary advantages to maintainers are lower maintenance cost, safety, and waste disposal. Evans suggests that the low-pressure system reduces stresses on plumbing and that a leak would be less likely to be a spray phenomenon. The elimination of accidents resulting from accidental removal of radiator caps from hot engines is an important safety consideration too. Also frequent maintenance checks of coolant additives are eliminated, as well as the subsequent adjusting of additive levels. Finally, coolant disposal costs are reduced, if not eliminated altogether, as no coolant needs to be replaced (limits of coolant life have not yet been found). According to Tourville, vehicles have been tested up to 1,000,000 miles.

SAIB NE-05-84R1
I asked Tourville if Evans had worked with Rotax or the FAA before the SAIB recommending that owners and operators use a waterless engine coolant was issued. He said they had not. I found this interesting considering that Evans Cooling Systems Inc. owns the patent and is the only company that produces this type of coolant. It appears that Evans Cooling Systems Inc. was not aware that the FAA was preparing to issue SAIB No. NE-05-84R1.

We Recommend

  • Article
    Recip Technology: Rotax Engines

    Recip Technology: Rotax Engines

  • Company

    Bombardier Aerospace

    Bombardier Aerospace offers 24/7 technical support for operators of Bombardier Learjet, Challenger, and Global aircraft. For Learjet technical support: (316) 946-6100 or

  • Press Release

    FAA: Water-Based Coolants Can’t Protect Rotax Aircraft Engines Past 120 Degrees Centigrade

    Evans Cooling Systems found itself the beneficiary of a recently revised FAA Special Airworthiness Information Bulletin (SAIB) recommending waterless coolants for Bombardier-Rotax (Rotax) 912 A, 912...

  • Article

    Tech Forum

    Evans coolant clarification In the March Issue of AMT Magazine I wrote an article about some service bulletins issued by the European Aviation Safety Agency (EASA), the FAA, and the Evans...