Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Mon, 27 Jan 2003 09:13:21 -0500
Message-ID: <redirect-2000186@logan.com>
From: "Gary Casey" <glcasey@adelphia.net>
Subject: engine corrosion
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<<Has anyone else noticed this kind of condensation after a flight?  It's
been a long time since I have flown pistons but I do not remember ever
having this kind of water on the oil cap.  To me this is probably why the
engine had internal corrosion damage to begin with.  Is there any kind of
crank case dryer available or is this just a by product of a twin turbo
charged engine?  I have now taken to removing the oil cap after each flight
to let it dry out.>>

Moisture build-up in the crankcase is pretty much unavoidable as the blowby
is combustion produces which is saturated with water vapor. It has nothing
to do with the type of engine.  As the engine cools these vapors will
condense.  The oil is what protects the metal parts from corrosion.
Occasionally one will see water droplets in cooler parts of the engine, such
as the filler tube as that might not get warm enough during a short run to
cook out the moisture.  Warm oil temperatures - should be 200 degrees or
so - will cause the excess moisture to evaporate during operation, keeping
the problem to a minimum.  The consensus is that between flights colder is
better and a heated hanger promotes corrosion by keeping internal parts
warm.  Opening the filler cap may allow moisture out, but I would think it
would take several days for the crankcase to dry out.  The best approach is
not to worry about it - fly the airplane every 2 weeks if possible and use a
detergent oil (most are).  I would guess the original problem was cause by
long periods of inactivity in a warm, humid environment. without adequate
storage precautions.

Gary Casey