Mailing List flyrotary@lancaironline.net Message #14873
From: Leon <peon@pacific.net.au>
Subject: More on Corrosion in Stored Engines.
Date: Thu, 6 Jan 2005 13:02:04 +1100
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Guys,
 
Something I forgot to mention.  Another way of inhibiting the internal water galleries of an engine that is to be left for considerable periods of time,  is to use machinist's soluable oil (you know,  the milky coolant stuff you see on lathes and mills).  In daze of old when knights were bold,  (and back when blokes wore hats),  soluable oil was "The G-O"  to prevent corrosion in cooling systems. 
 
It's only foible was that it would soften rubber hoses after a while,  so you had to change them on a regular basis,  otherwise disaster would strike (usually on a hot day going up a hill) as surely as Granny Smith Apples are green.  But it certainly prevented the formation of that turbid orange/brown slurry in radiators and blocks that often masquerades as cooling fluid!!
 
One of my mentors,  Ray,  was fanatical about lubricants and maintenence - he was,  at the time,  Maintenence Superintendent for a sugar refining company.  He was responsible for looking after all the bulk handling cranes,  front end loaders,  and all the bulk handling & delivery trucks.  One of Ray's cars was an absolutely immaculate black '37 Dodge,  and when he finally overhauled the engine after some 300,000 + miles and 35 years, (the crank case breather was getting a bit fumey),  the cooling passages and the rad core,  thanks to the soluable oil and regular flushing,  were as clean as my cat's whiskers.
 
This (soluable oil - not the cat's whiskers) will have the same effect as the soap solution (but it doesn't froth!!).  Both exclude air from the metal surfaces to inhibit oxidation and galvanic corrosion.  As the water evaporates from the passages,  it leaves a thin film of the oil itself.  Where the water cannot get out,  it still does its trick like it does on machine tools.
 
Cheers,
 
Leon
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