Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Sun, 25 Aug 2002 17:09:37 -0400
Message-ID: <redirect-1711562@logan.com>
From: StarAerospace@aol.com
Subject: Re: Engine Heaters Cast as Bad Ideas... Acid?
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There's a lot more than oil and water in the salad dressing in the crankcase. 
 100LL contains tetraethyl-lead which, when burned, produces lead vapor which 
deposits on everything it touches.  Some of it even gets on the valve seats 
where it does some good, while the rest goes to all sorts of places we don't 
want it to.  Over time, this would build up to unacceptable thicknesses.  
Something has to be done.

Enter scavenging additives.  These are combustible additives that contain 
REALLY nasty, corrosive, and sometimes carcinogenic chemicals that clean out 
the excess lead.  They are also really bad pollutants and are the unspoken 
environmental reason for banning leaded fuel.

Traces of everything the engine burns end up in the crankcase, especially 
with the sloppy piston clearances of air cooled engines not using TBC's.  So 
along with the oil, water, ash, shellac, carbon, lead, etc., there are trace 
amounts of these corrosives.

Water by itself isn't that corrosive.  Where its power comes from (if we want 
to call it that...) is in dissolving almost anything ionic into individual 
positive and negative ions and creating a corrosive solution.

Keeping the engine warm all the time is asking for corrosion;  warming it up 
just before starting it makes sense, since everything will be much closer to 
operating clearances.  Plug it in during the 30 to 60 minutes that it takes 
to load up and get the weather and it wouldn't have much time to cause 
corrosion.  Like the mixture control, engine heating can be not-used, 
misused, and abused.  It's all up to the operator.

M2c,
Eric Ahlstrom