From: Sky2high@aol.com
Message-ID: <7d.26d0812.260629dd@aol.com>
Date: Sun, 19 Mar 2000 08:02:21 EST
Subject: Oil temperature control,Thermostatic Valves
To: lancair.list@olsusa.com
Mime-Version: 1.0

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Experimentation is the mother of truth.

The thermostatic valve in a Lycoming 320/360 (Vernatherm) never completely 
closes the oil path to the cooler (See Gary Rodgers comments, LML V1 #2).  
Examination of the Vernatherm shows that it is a plunger whose length is 
controlled by temperature. This is a continuous operation beginning from some 
low temperature (maybe 80F) to fully open at about 180F.  The oil faucet to 
the cooler is always open to some degree (pun intended) until full flow at 
180F.

Cruise operation in dense cold air (not the hi-altitude thin cold air), where 
true airspeed can be less than indicated and engine cooling is great, results 
in oil temps that may not rise above 150F.  This can be problematic because 
combustion byproducts and water are not cooked out of the oil.    

Observation has shown that a winter oil change followed by low oil temp 
operation results in the oil darkening in a few hours.  Summer changes and 
operation at higher oil temps (180F-200F) keeps the oil looking fresher, 
longer.

I recently installed an air door on the oil cooler air inlet (instrument 
panel knob - cable contolled) which has given me complete control over the 
oil temps.  On cold winter days the air door is almost totally closed and the 
oil temp is maintained at 180 degrees.

Scott Krueger 
N92EX

P.S.  Gary, I live in the Chicago area and we blame Canada for our cold air 
masses.  Who do you blame?

 

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