Coolant Choice?

[SWeidemann]

I will be draining my coolant in order to change out the engine mount and install the optional cabin heater. My question is what coolant should I put back in the engine?

This 912 ULS has been using "water" coolant and I have been told by some of the folks I bought it from it has larger radiators since it was flown in AZ most of it's life. However, the "waterless" Evans coolants looks like good stuff for a number of reasons, and I am considering it. If I go to the Evans, how much flushing will have to be done?

Advantages of Evans that I see:
Will not freeze. No boiling. Low pressure.

I'm sure there are current experiences and opinions.

Thanks much, Skot

[Micro Mong Bldr]

Hi Skot,
Does Rotax have anything to say about this? Remember, nothing else has the specific heat of water.
Cheers
Larry

[Av8r_Sed]

Evans main benefit is to allow higher temp operation without boiling, a real advantage in very hot climates. The downside is you can only top off with Evans if you're out on a trip and need to replenish. If you're mainly flying in the midwest I wouldn't bother.

[Dave S]

Hi Skot,

I have been running Evans (waterless - propylene glycol) in our plane since new (912ULS). At the time Rotax instructions indicated to use this. Since that time, Rotax has recommended both options: 100% propylene glycol - Evans waterless or Ethylene glycol 50% + 50% water.

Some folks run a little higher temps with the waterless than they do with the 50/50 ethylene glycol - the mix has a little better specific heat which helps keep the temps down and it probably has a little lower viscosity than the 100% propylene glycol.

I decided to stay with the evans as I have never had any issues with the temp; and, I like the idea of the higher BP of the Evans. The temp issues can be aircraft specific.

If you change from mix to Evans, Evans sells a flush to use after draining out the old stuff - refill with the flush, run and drain - then install the Evans.

If you go to the Evans website or maybe even Aircraft Spruce, you should be able to find current directions.

Bottom line you can use either - just follow the instructions for the one you use.

BTW - the other use of propylene glycol?.....it's an approved food additive. Often shows up in dog food as a moisture sequestrant.

Sincerely,

Dave S
KF7 Trigear
St Paul., MN

[Av8r3400]

I've put hundreds of hours on Dex-Cool without any issues - in your same climate. It's available everywhere if you need some and in an emergency you can use water as a filler.

Evans is a great product, but it's hard to come by in a pinch if you need it...

[kmach]

Evans = around 25 degrees F higher running temps than 50/50 .

If you are having boiling issues while idling and taxi then evans will help out with that because of its higher boiling temp .

If you have high temps at cruise then 50/50 will help reduce the temps.

I switched from evans to 50/50 when I dropped the coolant to do the 5 year hose replacement and add in a thermostat.

I am very happy with the 50/50 temp numbers, as well as ease of topping up if ever required

[SWeidemann]

Guys,

I appreciate the responses. I am leaning towards the 50/50 water mostly because of the option to simply add water "in the field" if there is a leak and the fact there are no known overheating problems with this one.

Thanks, Skot

[Olle1975]

Hello,

during winter I use a mix of 50:50. By hotter temp during summer I change the liquid and fill up with 60:40 (water:antifreeze) mixture.

Anybody done the same procedure?

Olaf

[Dave S]

Hi Olaf,

Just curious; what kind of temperatures (aloft & on the ground) is your plane exposed to when you seasonally run the 60:40 mix?

Thanks,

Dave S,

KF 7 trigear
912ULS Warp Drive
St Paul, MN, USA (snowing again today)

[cubtractor]

I had the same experience as Kmach. About 25 degrees hotter with the Evans.