Search the Community

OK; this is a continuation of my engine saga of apparent excessive oil use here: Upon further investigation, we now found excessive oil coming out of the air-oil separator of my IO550G (see STC# SA02033AT, http://www.cessna170.org/OilSeperator/OilSep.html#Install). In fact, after 15 hours of flying after my last oil change, I had a black "cake" on my nose gear doors -- which came from the vent of that air-oil separator. Note that I don't see any oil on my hangar floor. One explanation is that I have excessive blow-by, creating pressure in the engine, which perhaps is overwhelming the air-oil separator? But I am grasping at straws here: Is there another explanation? Maybe the life time of those air-oil separators is limited (mine is 11 years and probably 1300 hours or more old, or so). Clearly I am blowing oil overboard, but mostly while flying and hot it seems. What puzzles me is that I had the problem (excessive oil usage, about a quart every 3 to 4 hours), then it went away for no apparent reason for one 35-40 hour oil change cycle, and now it is back. Does anyone know under what condition this air-oil separator would start blowing stuff overboard, instead of returning the oil to the engine? Really puzzled by all this -- and obviously trying to avoid experimental top overhauls (all the compressions are pretty good still).