Rotax 912iS overheating

[kmach]

Something to consider,
different propellers with their different blade designs push air through the cowl different. Some dont produce allot of airflow close by the prop hub, this affects temps on the ground.

[Guy Buchanan]

K-IV with 912uls. I don't think you should be having heating problems on a K-IV, there's plenty of radiator and oil cooler. Need pictures to see what you're doing. One thing I did that I don't know helped was to be very strict about shielding my oil and water lines from the exhaust, including shielding the oil filter. I know no one else does this, but it may have helped. (Indeed my problem is too low temps. 180F for oil and 140 - 160F for CHT's.) Remember the exhaust system is radiating heat at something between 800 and 1200F.

[Xengineguy]

Do you have a thermostat installed? If you do . It is sometimes almost impossible to get all
the air out of the cooling system w/o putting the system under a vacuum then
filling it. Most newer cars require this procedure.

[mr bill]

What kind of equipment do the auto people use to draw a vacuum? I have been wrestling with this issue since early November. For the moment I have no thermostat, but later in the spring when it warms up enough to work on it, I will resume work on installing a thermostat. Odd thing is, thermostat worked well when ambient air was above 45 F, but thermostat would not open when temp dropped below that.

[Xengineguy]

What kind of equipment do the auto people use to draw a vacuum? I have been wrestling with this issue since early November. For the moment I have no thermostat, but later in the spring when it warms up enough to work on it, I will resume work on installing a thermostat. Odd thing is, thermostat worked well when ambient air was above 45 F, but thermostat would not open when temp dropped below that.

Hi Mr Bill,
The vacuum system is available from snap on and many other vendors
maybe eBay also. It simply takes the place of the radiator cap
You hook an air hose to it and it creates a vacuum on the system.

The thermostat problem is likely lack of enough hot coolant to signal the thermostat to open. Do you have a small hose from the thermostat to the inlet
Side of the water pump? If you do you might need to drill one or two 1/8” holes
In the thermostat to bypass a little more coolant. More signal. Hope this helps

[mr bill]

I will try your suggestions after the weather warms up. My fingers don't work as well in the cold, as they used to. Thank you!

[ofergd]

A few answers and comments.
I am running a 912iS with computer controlled ignition and fuel injection. At full throttle it runs rich but below 97% power it turns to economical lean of peak, there for it runs hotter than the regular 912 ULS.
The big overheating problem is when on the ground while taxiing.
Anyway, thanks for the advise

Ofer Gd

[Gawilkie]

Not all oil coolers are equal in their ability to cool oil. My five kit came with an Earls cooler it could not handle the temps for the 912uls, it was located at the front of the cowling. I tried everything but it still ran too hot. I called Kitfox and John McBean told me the new oil cooler and the different mounting location would cure the temp problem. He was correct, now I have to tape parts of the oil cooler to get the oil up to temp. Cht and oil temps are somewhat related high oil temps contribute to overall engine temps. If you have the old style oil cooler replacing it with the new style will probably cure your problem.

[ofergd]

Also all cooling is related, I have problems with cooling the water. Oil tempetatures are high, but OK. Coolant temperatures are too high. I have an old type Rotax heat exchanger approximately 4" by 18" that I got with the kit. I just purchased the currant Rotax cooler with the same cross section area, and looking for an installation configuration to get sufficient cooling.
Maybe I should have baught the larger cooler from Jhon.

[Jaguar56]

Pulling plane out of annual I was at the runup area holding for inbound planes. Fairly stiff wind. I had turned the plane to watch inbound and the coolant temps started climbing fast. OAT about 85. Reached red and I shut it down.

Thinking I might have an issue, turned the plane in the wind and waited a few minutes. Started things up and seemed to hold a little over 200. Decided to launch and stay in the pattern. Once in the air the temps fell down to normal.

Lesson for me was to try and keep it in the wind as much as possible on the ground. Heat backs up fast when wind comes from the rear.