I have the most baffling problem in the history of aviation. In
January, the engine in my Mooney 231 was overhauled by a reputable
shop. Since then, I can not fly at high altitudes (above 15K) without
consuming mass quantities of oil. It appears the oil is coming out
the breather tube.

After spending a month at the Mooney factory we learned the following:

1. They hooked up an airspeed indicator to the oil dipstick tube and
discovered that, at altitude, opening the cowl flaps will reduce the
crankcase pressure by nearly 1/2.

2. It isn't the crankshaft seal (already replaced that).

3. Not the position of the breather tube (Mooney verified it to be
correct) and today our local shop removed the elbow from the end so
that the tube now ends well inside the cowl (ensuring it's not in a
low pressure area). Didn't help at all.

4. Forty minutes at 17K will use in excess of two quarts. Below 15K
there is no visible oil loss.

5. Compressions on all cylnders are between 74/80 and 78/80.

The airplane has both a Merlyn Automatic Wastegate and the Turbo Plus
Intercooler.

Any thoughts??

Thanks,

Steve Conley
N231ML - SAC