Brad
I have been going trough a lot of trouble shooting on my Legacy
IO-550exp related to oil blowby. I have the Andair separator. My problems
related to two issues. If you are blowing a lot of oil this system can
be overwhelmed and if it fills to the outlet port. You will really start
blowing oil because of back pressure. I originally plumbed into the
accessory case for the drain back oil with poor results on long trips.
Lancair recommended this but Continental, Airwolf, M20, Cirrus all say the
only low pressure place to return oil is the rocker valve cover or push rod
tube. The accessory case sees high crankcase pressures and has oil
spraying onto the port. I also tried a remote collection cup sold by Andair
which worked OK till it filled. I am now plumbed into the rocker valve cover
with good results but do not have enough data on long flights to be sure. Many
of these systems rely on pressure from a vacuum pump to aid siphoning back to
the crankcase. Without that you have a little disadvantage and be sure
there is good gravity feed back to the engine.
Why am I loosing so much oil? I think oil levels play a very
important part in this and would like to hear from others on their
opinion. I originally ran at 6 quarts because the common wisdom was that
anymore and it would just get blown out the breather. I am worried that
anything less than 6 could cause cavitation and foaming in the oil pan and
accelerate the oil blowby problem. Cirrus specifically recommends not letting
the level drop below 6. Not a lot of fun watching oil pressures drop from 75
to 50 and getting out of the plane and having the belly smeared with oil. I am
now running closer to 7 and hope this gives better results.
My oil temps run near 180 and have never gone above 200 except during
extended ground operation. I have the oil cooler door and tried removing it
because I never used it but my oil temps were to low in the winter. Home
base Vermont.
Hope to visit with a lot of you at Oshkosh.
Peter
Hebert
N23PH LEG2/G
pjhwfd@aol.com
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