I have been chasing a coolant leak on my 914F3 engine. The engine has had a recent 5-year hose replacement completed. Flew for about 12 hours and a leak started...very slowly. Initially I noticed a small "spray" of coolant in the neighborhood of the overflow bottle - the upper cowling wasn't particularly stained but the firewall and the electronics mounted there was sprayed with fluid. Initially there was always fluid in the overflow bottle - with either a hot or cold engine (cold, it was down about 1/4 of the way). After a few more hours of flying, and continually adding fluid, the leak is now significant - there is never fluid in the overflow bottle, and I've constantly added fluid prior to each flight. However it isn't flyable considering the leak rate now. Found a few loose hose clamps, including one that was absolutely loose and free to rotate. Flew again for about 45 mins and the leak seemed significantly better but not resolved. Flew again for another 45 mins and the leak became major again. Don't think the hoses or clamps are the problem.... is there a possibility the cap is bad on the expansion tank? Any other options work taking a quick look at?
