Thanks Ralph.
I got the aircraft back a couple of days ago and what a difference! Smooth throughout the rev range and the coolant seems to be behaving itself as it is going into the expansion bottle when hot and returning to the header tank and engine as it cools (which it did not do before). I have only flown it for 2 hours / 4 flights, but so far all is good.
So...what has been done on it?
The aircraft manufacturer checked things themselves and then returned it to the Rotax importer who has spent 17hrs working on it. The gearbox was removed to check crank alignment, crank angles were measured, the prop was slightly out of balance and a couple of washers added (but an alternative prop had been previously tried), differential compression test on cylinders, coolant system pressure tested hot and exhausts removed to check for the leakage Ralph has described, one carb flaot replaced as it was slightly 'heavy'. carbs rebalanced....the engine was then run with an accelerometer fitted and that showed no abnormalities. A lot of checks, nothing particularly significantly doneexcept changing the carb float ....yet it now seems to work fine.
I was anticipating that some 'fault' would be found and rectified but apart from the carb float this does not seem to be the case - and that would obviously not effect the coolant issue.
I would like to thank the aircraft manufacturer (P+M) and Rotax importer (Skydrive / Conair) for their help and patience in rectifying this problem.
Andy Buchan
