Thanks Jim
I am trying to duplicate the climb and test it. I guess it was a combo of High heat , high RPM, high weight and most likely high density air.
I lost a quart of coolant but I can't see where it came from is my problem. I think the leaked stop once I leveled off into cool air? Otherwise I was diverting
I am going replace the hoses and clamps first. We are guessing they are original and I will clean out the radiator . How about that synthetic coolant rotax recommends? The radiator doesn't look that dirty but this is a new plane to me so who knows if it was ever cleaned out or how old the hoses are. I could smell a hot hose was the only thing that told me there was a problem.