Non-mechanic's opinion: Blowing out two quarts per 10 hours may be tolerable but it makes enough mess that it's worth fixing.
Fixes assuming that the oil is coming out the breather hose: 1. Get the elbow for the breather hose that has an extension inside the crankcase. This was standard on some of the later Coupes. Lots of older machines have been retrofitted by having the appropriate size tube silver soldered into the elbow. The idea is that there's a lot of oil splashing around inside the crankcase, splashing on all the walls. There's always air or gasses being blown out the breather hose. The gasses come from blow-by from the cylinders or whatever, even on a plane with good compression. With the standard elbow, the air blowing out the breather tube sets up a flow sucking along with it the oil on the crankcase wall. Our Coupes seem to have a slightly enhanced blow-out effect because the engine is tilted down to the right a touch. An O-200 engine in a Coupe sometimes has a LOT of blow-out. With the short tube sticking a little way into the crankcase, the air going out the tube doesn't suck oil off the crankcase wall. Just air goes out the tube. #2. When the breather tube comes out of the crankcase, it can either go down in front of the engine to exit, or it can go up and back over the cylinders and go down behind the engine. If it goes straight down, any oil drops that get out of the elbow _will_ be lost down the tube. If the elbow is turned so the hose goes up to the rear on a slope, an escaping drop may flow back down into the engine. Easy and cheap but not the definitive solution. #3. An oil/air separator. This would drain separated oil down to the sump, I guess. Summary: I knew a pilot with a new O-200 installation who had to make a forced landing on his first 2.5 hour flight for loss of oil. He implemented suggestion #2 (above) and added an air/oil separator which allowed him to do 2-3 hour flights before oil exhaustion. It was the elbow extension into the crankcase solved the problem. -- Ed Burkhead Peoria, Ill. Ercoupe N3802H, 415-D
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