Interesting Motor Discovery-OS1.60

[george kennie]

Sounds very familiar. I had a S.T. 51 that had been loaded up with Klotz
200( I mean full) and put away in a plastic bag and stored for  an
extended period of time. A few months back I decided that it was time to
give it a test run to make sure everything was still A.O.K. I threw a
prop on it and flipped it over and mentally observed "wow, what
fantastic compression!"  I took it out to the back yard and benched it
up and fired it up and ran it up to max rpm and was favorably impressed
until I brought it back to idle whereupon it immediately ceased to
reciprocate. I stood there with my mouth open as the prop lightly
windmilled. The thing had absolutely no compression. I mean quadruple
zero, triple O, double ott, nothing!!!! Upon inspection it was
discovered that the piston
ring was virtually welded in the groove. Attempts to dislodge the buggar
only resulted in a broken ring. Ultimately the ring was replaced  and
all returned to normal.
So I guess the lesson is that synthetic oils may be lacking as a
protective agent or of questionable lubricity.
Georgie



Bob Pastorello wrote:

> Finally got around to getting the Wagstaff Extra airworthy, after not
> being run for the winter.  Felt rough, so tore it down.  Bearing was
> not really bad, although a little rust was present (wasn't a SS
> bearing).  Upon investigation, noting the serious lack of compression,
> I proceeded to replace the bearing.    While the piston was out, of
> course I cleaned it....lo and behold...RING rusted SOLID in the
> groove.  After careful working with my Amsoil spray, it freed, and I
> cleaned the groove.    What was interesting was oil on top of the
> cylinder, and on the cylinder wall (not a lot, but a film was
> there)...and the side of the piston around the ring groove was bone
> dry. Fixed it all up, ran like a top, very smooth - so shoudl be good
> to go.  I have never seen a ring stuck like this before, and just
> thought I'd share the tale in case anyone runs into inexplicable
> roughness and low compression....
> Bob Pastorello
> rcaerobob at cox.net
> www.rcaerobats.net
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