What cylinder head temperatures are you seeing in flight? I have done a few short ground runups to 122F oil temp and by then I am just going over the 248F CHT alarm limit.
The top hose of the radiator is warm and the expansion tank's coolant level has moved down to midway between min and max after the first run so I am reasonably sure the coolant is moving. Scott expressed the idea that ground run may not push enough air through the radiator to get 'regular' cooing and he well may be correct, but what are you seeing in flight?
As an aside, I at first thought the CHT max of 248F might be an error because that is the max for the oil temp also..a real coincidence...and looking around on the internet some Rotax 4 cylinder engines have CHT max given as high as 284F (a number reversal that led me to suspect an error in the instructions but I guess it wasn't.)
The top hose of the radiator is warm and the expansion tank's coolant level has moved down to midway between min and max after the first run so I am reasonably sure the coolant is moving. Scott expressed the idea that ground run may not push enough air through the radiator to get 'regular' cooing and he well may be correct, but what are you seeing in flight?
As an aside, I at first thought the CHT max of 248F might be an error because that is the max for the oil temp also..a real coincidence...and looking around on the internet some Rotax 4 cylinder engines have CHT max given as high as 284F (a number reversal that led me to suspect an error in the instructions but I guess it wasn't.)