OS 46 FX rattle noise
This engine has 2 gallons of fuel through it and has developed a strange growling/rattling noise easily heard in the air at 1/2 - 3/4 throttle. both the idle and the high end show no signs of the noise. It isn't as easy to hear on the ground, but it is audible. I run a 10X7 on 15% omega and the temp is about 35-55 right now in Wichita, KS at an altitude of 1000 - 1400 feet. I also have another OS 46 FX with about 1/2 gallon of fuel through it that does the same thing... just not as loud. I think that the airframe on the first one amplifies it a bit. I'd like to know what the problem might be, it really does sound like the engine has some serious trouble, it has never been in a crash and NEVER had a lean run. I don't use after run oil but I do run all the fuel out of them after every flight. Local field experts have adjusted the low and high end and the engine purrs like a kitten on idle as well as giving instantaneous throttle response. I am at a lost to what the noise is though, a few think it might be the bearings but this thing is only 2 gallons old!
Thanks for any help.