Model Forum / Radio Controlled / Air Models / June 2006

Mark-

The varnish is cooked veggie oil, so products intended to remove that
work well.  Oven cleaner is widely used, some brands work better than
others.  I got a pint can from a food service supply store that works
well.  It is a gel that looks and smells very much like the product
"Demon Clean" (or similar, not sure of the exact brand name) sold by
Dave Gierke for cleaning model engines.  
Another widely used solvent is antifreeze - soak overnight in a warm
crock pot.  
No solvent I have used does a complete job.  A Scotch Brite pad and
some elbow grease will be needed too.  

Abel

I use an aerosol product called Mar-Hyde Tal-Strip II aircraft coating
remover. I usually find it in auto supply stores. You just spray the
part, wait a few minutes and then wipe it off. In most cases you don't
even have to use anything abrasive. One word of caution though. You
need to use the stuff in a well ventilated area and use gloves. I have
also read that people soak the parts in heated antifreeze. Apparently
that works too but personaly I prefer the Mar-Hyde product.

There was a great article two months ago by Dave Gierke in Model Airplane
News on the topic of de-varnishing an engine.  Try to get your hands on that
issue.

A letter to the editor following Dave's article suggests a product called
"Dawn Power Dissolver" sold in most grocery stores for removing burned on
grease.  I've tried it on external varnish and works great too.  But read
Dave's article.

Ted shuffled out of his cave and grunted these great (and sometimes not
so great) words of knowledge:

The easiest (and most effective) way to clean the engine is the crock
pot method.

Take a crock pot you WILL NEVER USE FOR FOOD AGAIN (The anti freeze
poisons the pot and you will never be able to get it out of the pores of
the pot).  Put the pot in a sheltered OUTDOOR area. (The fumes WILL GET
TO YOU otherwise )  Use PERMANENT type antifreeze in the pot.
Disassemble the engine as far as possible. Make sure to mark the top of
the piston, top of the sleeve and the con rod with a mark to indicate
the rear of the engine.  (I scratch a mark in them with a scribe.)

Put the engine and parts in the crackpot.  Make sure they are covered by
the antifreeze, turn the pot on low and come back in 8 - 10 hours.
Remove everything from the crock pot and flush well with water, then dry
well (I also put them in a 175 - 200 degree oven for about 30 - 45
minutes ).  The parts will come out sparkling clean and like new.
Lightly lubricate with some afterrun oil (Marvel Mystery oil or air tool
oil ) and reassemble the engine.  Replace the gaskets in the engine.

Extremely stubborn areas/parts (mufflers) may need a second treatment.

Mark, as a C/L flyer therfore a user of older engines, I would not
reccommend cleaning or replacing the piston/sleeve unless the
compression is very low.  In older engines the varnish helps to improve
the piston/sleeve seal. Cook the rest of the parts.

Phil