912ULS High Oil Temperature

Roger,

Honestly - the only things left that I believe are possible:

• Engine running lean - I don't believe this is the case, but possibly
• Coolant not flowing due to blockage - I had changed the sprag clutch in 2020 and saw no blockage, or water pump issues. I haven't found any compressed coolant or oil lines at all. I also just replaced the radiator with no difference.
• Oil/Coolant heat exchanger dirty/clogged - I haven't checked this, but I believe it is functioning correctly. 
• Collapsed hose - I haven't seen anything like this at all
• Sensor measurement error - Not the case. I verified the sensors with boiling water, and verified the instrument with a 62 ohm resistor (shows 100C). I have swapped sensors, changed sensors, changed wires, ran a 12 gauge ground wire to the block to the instrument, etc.
• Airflow over engine - I believe this is the culprit. I have heard from other owners that a change in the cowling solved their issue. I'm going to try to find a way to verify this. I may put thermocouples around the cowling and fly it to see what the result is - if that tells me anything

Ok so get this. Tonight, I put the 1/2" spacers on the cowling sides and went for a flight. Climbed to 2200 and cruised at 4700RPM. CHT was 103, Oil Temp was 107! It dropped quite a bit. Although, today was 73 degrees and yesterday at the same time was 81 degrees.

I increased the RPM to 5000 and CHT climbed to 104, Oil temp to 109C. All within limits. 

Its supposed to be warmer tomorrow. I may go twice - once with the spacers and once without the spacers to see if I am crazy