Craig,

I used a analog manometer, ran the hose thru the cabin heater valve and
tapped it into the crankcase vent line just before the Air/Oil Separator.
You can tap into the Crankcase Vent anywhere but it would probably be better
about 12" or more from the outlet.  The gauge will indicate at what power
setting and flight condition pressure is changing.  You might call Alan at
Barrett
Precision Engines and get his take on your problem

Steve Colwell  Legacy 550


Clark, Steve, and Fred,  

What do you recommend for monitoring crankcase pressure in various phases of
flight?  I'd assume it's something that temporarily replaces the oil
dip-stick cap?  Running wires into the pressurized cabin would be a pain for
a temporary test, but could be managed.

The TSIO-520WB on the left side of my P-Baron infrequently dumps about a
quart a minute out the breather (clean oil on the flaps). Twice happened on
initial climb, last time on low-power descent like you describe.  Basic
compression test good, did find that the breather outlet is in front of the
cowl flap exit, whereas on others it is a couple inches aft.

> Your oil on the belly and excessive use problem sounds like my
> original Performance Engine.  I finally installed a pressure gauge in
> the crankcase breather.  My engine would show zero pressure on the
> ground regardless of power setting.  On the takeoff roll still zero.  
> At about 120 knots it would jump to 5" and stay there until power was
> reduced.  When MP was slowly reduced to about 18" the pressure in the
> crankcase vent line climbed to over 30".  That was when all the oil
> was being blown out the breather.  The prop was unloaded just enough
> to allow the worn rings to flutter