I had a blowby problem with my Coupe that was very frustrating too. Oil would
seep out of the crank seal (and on to the windscreen) and out of a couple of
the pushrod tubes. I had three different mechanics replace the crank seals with
new ones, to no avail. Finally, one of them said "try this" after bending my
breather tube back slightly behind the exhaust pipe and slightly backwards.
That fixed all my problems. We had switched exhaust earlier, and didn't
realize that the positioning of the tube is quite critical. By having it
slightly pointed the wrong way, it created high pressure in the crankcase and
problems only showed up in flight when oil started showing up on the upper cowl
and windscreen.
I recently installed new exhaust again, and had the same problem show up.
Again we had to play with the positioning of the tube, and added a short hose
to get the thing "downwind" and all was good again. I hope that your problem
is a simple as that.
Marty Duke N846MD KRNT
