On Mon, 16 Aug 2004 02:35:58 GMT, "Jay Honeck"
wrote:

Any aircraft engine crankcase I've been inside of has relatively small
slots below the crank where the case halves meet effectively isolating
the sump from the crank in regard to "windage".

Ah! The man who truly *knows* weighs in!

:-)

So how 'bout it, TC -- is the M20 a good thing, a bad thing, or 'bout the
same thing with regards to my O-540?

I've read mixed reports about the M20, unfortunately have no personal
experience. Have heard people swear by them, have heard people swear
at them.

Have taken care of several Bo's with the original Walker (?) air/oil
sep. They were for the most part equipped with wet vac pumps as well.
In those cases, there was what I would consider to be an acceptable
accumulation of oil on the belly.

I can't really speak with any authority on the whole "putting crud
back in the crankcase" deal, but I can add that every 325-350 hp
Navajo breathes through a factory-installed air/oil sep. My guess
would be that these engines tend to be heavy-breathers. When they get
up there in hours, the oil stripe on the bottom cowl gets heavier, in
spite of the air/oil sep.

Was never of the mind to bypass one to see how much difference they
make. Cleaned the inside of them rather infrequently, usually at
mid-time (900-1000 hrs) and at TBO.

We ran the Navajo's at 11 qts after an oil change, usually keeping
them between 10 and 11 in service (dump in a qt when it get down
around 10). Actually, never really thought about the air/oil sep being
a factor in determining that level.

Only ever had one come up shy on TBO-catastrophic turbo failure w/oil
contamination. Don't think I coulda blamed that one on crud from the
ari/oil sep...

TC