High CHTs

Problem finally solved.

It was an airflow issue.  After trying a new radiator cap and changing the coolant twice, fixing the carb heat (which was partially on) wrapping the exhaust manifold to keep heat away from the air filter and a few other things I noticed that when doing an engine run up with the upper and lower cowling removed the problem didn't occur.  It is actually near impossible to get the oil to 50 C with the lower cowling removed.  Yesterday I measured the radiator cowling openings on four other planes in the hangar that use the Rotax 912 engine and found they all had about 50% more opening than me.  This morning I took my Dremel tool with me and opened the cowling up so the opening is now a bit over 30,000 square mm in size (rather than 22,500) then did an engine run up and everything is as it should be.

Thanks for the replies.

Chris

Don’t forget that you can mask off part of the oil cooler if you are struggling to get the oil temp up.