Rotax 912uls hi CHT and coolant temps

[kitfox812]

A lot has been said about the 912uls cooling. I have had CHT temps over 240degF for over 2 years in the summer. Not to red line but Not Comfortable to fly any distance with. I have over 1100 hours S7 and my Evans "lifetime" coolant and was ready for a change. I read an article, (I think by Roger) about using 50/50 Antifreeze instead of Evans would bring the temps down 25 to 30 degrees.
It works!!!! My CHT and Coolant Temp are down 25 degrees today with the same OAT as when they were in the 240 range. I am ready to take a summer trip again. BTW, I chose Prestone DexCool (Orange).

[Dorsal]

What instruments are you using?

[kmach]

I did the switch from evans to a 50/50 mix and also experienced the 25 degree CHT drop.:)

I have a dynon d120 monitoring the cht's , egt's , coolant temp ... etc

[kitfox812]

I have used the Grand Rapids 2000 EIS since I finished it in 2007.

[BigJohn]

A lot has been said about the 912uls cooling. I have had CHT temps over 240degF for over 2 years in the summer. Not to red line but Not Comfortable to fly any distance with. I have over 1100 hours S7 and my Evans "lifetime" coolant and was ready for a change. I read an article, (I think by Roger) about using 50/50 Antifreeze instead of Evans would bring the temps down 25 to 30 degrees.
It works!!!! My CHT and Coolant Temp are down 25 degrees today with the same OAT as when they were in the 240 range. I am ready to take a summer trip again. BTW, I chose Prestone DexCool (Orange).


I had the same issue a couple years ago with a 912uls and went to the DexCool 50/50 from Evans and dropped approx. 25 degree's, I then put in a much larger oil cooler and dropped another 10 degree's on the CHT and considerable on the Oil, Now I can fly the hot desert area's in 120 degree weather and not get my CHT over 220 in a hard climb.