Kitfox 7 912 ULS in the AZ heat

[vwav8tr]

Hi Fox Fam. Went for an early morning flight to beat the heat. OAT was 90-92F. The Water temp creeped up to just under 240F. Like a needle below Redline. Cylinder temps were 180F as was the oil. All in the green however, I’d like to bring that water temp down a pinch. Question to the seasoned folks, what temps are you seeing at 90F 3000’ MSL and 24” Manifold settings? Or do I just need a bigger radiator?

Thanks all!
-Scott

[jiott]

I am having a hard time with your temp numbers; cyl head temp on the later model 912's is actually coolant temp, and on earlier model it is still quite close to coolant temp. So how could you have 240 coolant and 180 cyl head temps? I think one or more of your temp sensors may be way off. If you have 2 cyl head sensors, as is standard, and they both agree I would be more inclined to believe them.

[Av8r3400]

I am having a hard time with your temp numbers; cyl head temp on the later model 912's is actually coolant temp, and on earlier model it is still quite close to coolant temp. So how could you have 240 coolant and 180 cyl head temps? I think one or more of your temp sensors may be way off. If you have 2 cyl head sensors, as is standard, and they both agree I would be more inclined to believe them.


100% agree. Where are you measuring "coolant temperature"?

[vwav8tr]

Excellent point. The aircraft is new to me so I'll trace down where the Water Temp is sourcing it's data from. Will report back. I'd feel way better if the Cylinders and coolant were 180F.

[avidflyer]

Here is a bit of a post by Roger Lee from the Rotax owners forum. 180 degree was redline on the Rotax 582 two stroke, but the 912 can run much higher. JImChuk

The 105C (221F) should be fine and is more accurate now with your new heads. What are your CHT's running? If you are using a 50-50 coolant mix then 248F should be the max temp.

[Shadowrider]

The new kitfox 7 radiators come with a port that you can put a coolant temp in. I am guessing your temp sensor is reading wrong. Take a heat gun and measure the radiator right by the sensor after running and see what it is reading? Guessing your CHT's are correct and your coolant temp sensor has problems?

[Dave S]

Scott,

Here is the authorative way to determine if you have the cylinder head temp or coolant temp version on your engine. Rotax has a running list of engine modifications. Easy peasy visual of the cylinder heads.

There is a photo/drawing of each version on page 7 of the PDF below.

https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-020.pdf


The new version cylinder heads started with engine serial number 6781410; however, an older engine could have had new version cylinder heads installed as service items so the engine SN may or may not apply. Best bet is the info in the service instruction above with the photos/drawings.

[vwav8tr]

Pulled the Cowl, turns out I have the old heads with the temp probe on the bottom. This reads CHT as I understand it. I also have a Water Temp Probe in one of the water hoses. I'm planning to pull that probe and test for accuracy. But wanted to follow up that I have Both CHT and Water temp.

Thank you all for guidance.
-Scott