Recip Technology: Waterless Engine Coolants

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

Has the engine temp on your antique, homebuilt, or unmanned aerial vehicles (UAVs) been running a little high lately? If it has, then Evans Cooling Systems Inc. (ECS) of Sharon, CT, ( has something that may help.

Replenishing your engine’s conventional ethylene-glycol/water coolant with its waterless type coolant should solve your overheating problem. But before you call, you need to check out the following service bulletins by the European Aviation Safety Agency (EASA) AD 2007-0155, and FAA SAIB NE-05-84R1 to get information about coolant usage. If you have or maintain a Bombardier-Rotax (Rotax) 912 A, 912 F, 912 S, and 914 F engine, check out the Rotax service bulletins SB-912-043 Revision 2 (11/2/2006), and SB-914-029 Revision 2 (11/10/2006).

If you are aren’t operating or maintaining 912s or 914s, but still want the “down-low” on Rotax engines, go to and look up the March 2009 issue, in which AMT contributor James Careless wrote an article on Rotex engines. Careless interviewed Rotax engine expert Dean Vogel of the Aero Technical Institute. In the article, Vogel is quoted as stating that, “Rotax engines are a popular choice for certified light and homebuilt aircraft, auto gyros, and military UAVs.” Rotax wanted to keep these engines light, so it took features from motorcycle and auto engines, and created engines with external oil tanks, and that use motorcycle oil and automobile grade fuel. These engines are water-cooled, which brings us back to Evans Cooling Systems Inc. and the information recommended in the EASA AD and FAA SAIB.

EASA and FAA recommendations
Sometimes OEMs and regulatory agencies act in mysterious ways that are not always apparent to us, but the reason for these service bulletins is clear. Some models of the Rotax engine have been overheating, and if you use a conventional ethylene-glycol/water coolant and your engine coolant exit temperatures exceed 120 C, you may experience a loss of coolant, engine overheating, knocking, and engine damage that can result in an in-flight shutdown. EASA addressed this overheating problem when it published the service bulletin AD 2007-0155 in which Rotax owners and operators are required to use a waterless-type coolant if their engine coolant exit temperature will exceed 120 C.

Aircraft maintenance technicians tend to be pretty cautious when it comes to using new product on our airplanes. We too have taken an oath to do no harm. More so when we are addressing a serious problem like engine-overheating, and we should be informed about waterless-type coolants. Now, if you maintain heavy-duty diesel semi-trucks or are working on a Motorcross or NASCAR pit crew, then you probably already know the waterless-type coolant, as the non-aqueous blended glycol products (NPG+, NPGR, and HDTC) produced by Evans Cooling Systems Inc.

Evans Cooling Systems Inc.
Sometimes if you work hard and persevere good things happen for you. This is the case for Jack Evans, founder of Evans Cooling Systems Inc. Evans Cooling Systems is a company that is one of the pioneers and recognized experts in cooling systems and in waterless coolants. Evans spent years in research and development to help race cars run faster without overheating and creating damage from pre-ignition knocking. His efforts paid off when he concluded that the water in the cooling system was the root cause of damage in high-performance engines. Evans quickly recognized that a substitute coolant had to be developed to progress engine design and subsequent performance. After investing several million dollars and spending years on R&D the results are the waterless coolant product line along with many patents and patent applications that cover it.

The Evans waterless coolants have boiling or vaporization points higher than conventional water-based coolants, which is what Rotax, EASA, and FAA considered when they issued their ADs and SAIBs. When using waterless coolant in your internal combustion engine, you get greater thermal efficiency, reduced detonation, and pre-ignition emissions, and reduced engine-wear with low system pressure. The radiator cap is still there but you can remove it without a gusher attacking you.

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