update to my chasing down my oil leak on my 0-200

starter replaced, leaking oil seal, replaced a pair of pushrod tube seals

with improved versions from Real Gaskets in cylinder 4, pilots side front cylinder,

removed two cylinder hold down nuts and sealed the studs threads with high temp rtv, also on cylinder #4

removed two nuts holding intake spider to seal the threads with high temp rtv.

the leaks were a combination of all of the above, test flight today clean and dry, no apparent leaks.

They say if an 0-200 is not leaking it’s out of oil!

Hope it lasts, the moral of the story is don’t give up!


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O-200A breather , longer one as supplied with O-200D

I would be interested in a more detailed explanation of how crankcase oil makes its way to the carburetor on a running engine. Thanks.

It didn’t come from the crankcase Jim, it came from the intake valve spring area due to the increase in vacuum when the engine drops to idle (difference is 20” of water).  So any excess oil in the rocker arm area can get sucked back into the intake system on engine shutdown.  The decrease in pressure is a result of the throttle butterfly in the nearly closed position.  Still the observation is a bit rare even in a newly rebuilt engine.


Ok thanks. I have a breather fitting extension on my engine, so I was interested in your observation. I always have a small amount of oil in the carb box area when I remove the lower cowl, so I may have the same situation you describe. The amount of oil is so small as to make locating the source difficult.


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