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Evans waterless coolant

H

Harvey rv12

Well Known Member
I have Evans waterless coolant running in my Rotax RV-12. I have read that it runs somewhat hotter than glycol water based coolant. has anyone switched between the 2, and noted what kind of CHT difference results ?.
My CHT's are often bumping around the 230 deg mark, and I am wondering how much cooler it might run with conventional coolant.

Tom O.
 
Search this forum using the word "Evans." Several interesting and related threads. Why are you using Evans?
 
evans coolant

The Evans was installed on my plane when I purchased it. not sure whether or not to change to conventional.

am searching posts now.

thx
 
Evans

I'm using Evans coolant in my Subaru powered RV-9a. Some Subie users have switched to try to improve cooling but I don't know of any back to back testing. Personally I think there won't be much difference. The nice thing about the Evans is you can run as low as zero on the cooling system pressure and the boiling point is over 300 degrees. Also Evans is supposed to be better on corrosion resistance, and lasts indefinitely.

-Andy
 
I've had some experience with in on my Rans, haven't used it in my 12. Evans does run hotter, usually 10 degrees or so, it has a higher boiling point but doesn't transfer heat as well as glycol. You will run hotter with it, you don't have to worry about boiling but remember this will also raise your oil temp somewhat, something most of us hot weather flyers don't want.

Most everyone I know in the Rans community has switched back to glycol because we tend to fly into the back country where water is available and Evans is not. The two are totally incompatible so you can't add water is you have a leak.

Bill
 
I decided to run water and antifreeze in case I need to add coolant on the road. I figure water will always be available.
 
Hi Harvey,

Depending a little on your engine setup (i.e. open air engine versus closed cowl) Evans carries a 20F-30F temp penalty. Rotax doesn't recommend it any more. If your CHT's are 230F then this is a little hot for CHT's. Mine are 205F. I would think your oil temp would be up a tad high too. CHT's normally are approximately 15F-20F below the oil temp. This can vary slightly between engine and aircraft setups. As the guys mentioned water is easy to come by if you need to add and Evans isn't. Water does a much better job off heat adsorption and absorption. This is why fire department use it. It's the best inexpensive heat adsorbing coolant for heat (fire) out there.
 
I ran Evans for about 5 years. Switched back to conventional and my temps dropped about 18F. Wouldn't go back to it again. The coolant might be good for 300F but your engine will probably seize or be damaged way before that happens so that part is of dubious benefit. If your coolant temps are high, best fix the problem properly with a better rad setup.
 
rv6ejguy said:
I ran Evans for about 5 years. Switched back to conventional and my temps dropped about 18F. Wouldn't go back to it again. The coolant might be good for 300F but your engine will probably seize or be damaged way before that happens so that part is of dubious benefit. If your coolant temps are high, best fix the problem properly with a better rad setup.
Click to expand...

+1 Absolutely - you may be able to tolerate higher cooling temps, but lubricant capabilities have increased little (if at all for available oils) in half a century. Remember oil keeps the engine running.
 
Interestingly my CHT's are a little higher than my oil temp.
Based on what I'm hearing I am going to drain the Evans coolant and
Go with the dex/ glycol mix. Sounds like 10-30 deg reduction is possible.
Is there a thermostat in the 912?

Thx for the guidance
Tom O.
 
There is no thermostat, either in the liquid coolant cycle or the oil cycle. Some add one to the oil cycle (for faster winter warmup), search this RV-12 forum for "thermostasis"
 
Dexcool

As previous posters have mentioned, Rotax now recommends anti-freeze and water.

Specifically, anti-freeze that is labeled "Dexcool", run as a 50/50 mix with distilled water (do NOT use tap water). The mix can be up to 60/40 water/Dexcool.

Water has a higher heat capacity than anti-freeze.
 
dex-cool going in

I drained the Evans waterless coolant, and am filling with Dex-Cool coolant.
I will report back with temperature measurements, hopefully they drop by 20+ degrees.

Tom O.
 
Switch from Evans coolant

Hmm...maybe this is addressed somewhere else, I haven't looked, but since it's being discussed here and now, here goes...

If Evan's and water are totally incompatible, how do you drain and flush out the very last bit of Evan's coolant before you refill with Water/Dexcool?

Is it an issue? If not...cool (sorry)
If it is, will someone please describe or refer to the procedure to minimize the possibility of someone else doing damage.

(On behalf of someone who may benefit) Thanks!

Dave (Proudly overthinking problems and solutions since 1951) Welch
 
Dave,

It's not important when going in that direction (back to glycol), just flush it out with a little water and you're good to go. Add the 50/50 glycol.

The reason you can't have any water in with the Evans is because it runs so hot you're likely to boil any water mixed in with and create cooling voids because the water will turn to steam. The directions on Evans is very clear that if you have been running any water you must flush the system with a product that they make just for that purpose. The flushing product absorbs any water in the system and then you dispose of it before adding Evans.

So to sum it up. A little Evans in the glycol coolant - no problem. A little water in the Evans coolant - big problem.

Bill
 
DaveWelch said:
Hmm...maybe this is addressed somewhere else, I haven't looked, but since it's being discussed here and now, here goes...

If Evan's and water are totally incompatible, how do you drain and flush out the very last bit of Evan's coolant before you refill with Water/Dexcool?

Is it an issue? If not...cool (sorry)
If it is, will someone please describe or refer to the procedure to minimize the possibility of someone else doing damage.

(On behalf of someone who may benefit) Thanks!

Dave (Proudly overthinking problems and solutions since 1951) Welch
Click to expand...

Like BajaPilot says - flush with water - - but always use distilled water in cooling systems where aluminum is present (basically all).
 
No worries then

Thanks Bill, makes perfect sense.

I'd misunderstood the "totally incompatible" statement to mean that the Evan's coolant and water are not mutually soluble.

Whew...another non-issue safely avoided!
 
cooler temps

I flew the plane today with the dex-cool ethylene glycol coolant, 50-50 mix with distilled water. the temps were about 30 deg cooler than with evans waterless coolant. And for the first time, the CHT's were cooler than the oil temp. my CHT's in a climb were around 205, and then in level flight around 195. Conditions were 75 deg OAT, 5400 rpm.
I'm happy.

Tom O.
 
Originally Posted by DaveWelch View Post

If Evan's and water are totally incompatible, how do you drain and flush out the very last bit of Evan's coolant before you refill with Water/Dexcool?


Dave;
Evans says you can have up to 3.6% water mixed in.
 
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