Mailing List lml@lancaironline.net Message #21696
From: Gary Casey <glcasey@adelphia.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: air-oil separator
Date: Sun, 30 Nov 2003 11:07:37 -0500
To: <lml@lancaironline.net>
<<A question.  If you are going to dump the oil overboard then why even have
an air/oil separator?  Seems to me that it would be cheaper and easier just
to do what the factory engine is doing, fun a tube over the exhaust and burn
it off as it drips down the hose.  ????

>>>Amen.  You should either catch that crap in a receptacle of find a way to
dump it overboard (my preference).  It is nasty stuff.>>

All those comments lead me to make an observation and ask a question:
Certainly there is a lot of oil droplets suspended in the crankcase vapor,
but probably 90% (99%?) of these are separated out inside the engine.  I
assume the engine manufacturers decided it wasn't worth the cost and weight
to design in a more thorough separating system in order to catch some of
what remains.  The few percent remaining are then categorized as "nasty
stuff?"  How could they be any more nasty than the oil that is caught inside
the engine?  My observation is that the oil in the catch tank is only
"nasty" because the tank is cool and allows the water to remain.  If it were
drained back into the crankcase the normal evaporation would take out the
water and then it would be "good stuff."  Converted to a question it would
read "why not just drain it back in the engine like the designers intended?"

Question:  I have heard of the blow-by ports in the exhaust pipes
occasionally filling with carbon, potentially causing an obstruction.  Is
this a problem?  Should the breather tube instead by just ported overboard?
How does "New Cessna" do it?  Okay, that was more than one question.

Gary Casey


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