I mowed with my 322 today, all good for an hour. Then, HUGE cloud of blue oil came out from under the hood & side grills! Moved about 30' to a flat spot and the smoke had already stopped. I shut it down, opened hood, and looked around. Large spot of oil on inside of hood, right side, and no other place. No signs of oil on engine or any other place! I let it sit for a half hour, turned key, and it fired right up...no smoke, no missing, everything normal! I finished mowing in another hour with no smoke/problems. This is the first and only problem I've had in 2 years, and (right now) I'm not too concerned.
Sooo, here's what I'm thinking: One valve hung up open allowing either combustion or exhaust pressure to blow back into crankcase...past rings, valve guides???...and blow oil out fill port on valve cover...I haven't located (or looked) for crankcase breather, but dip stick is on opposite side of engine and those are the only 2 exits I can think of.
Anyone have thoughts? Bob