In the case of Creavey I think the Teflon is extruded first and the
silicone
is
injected in the liquid state. This is probably done in a mold so the
pressure
required to inject the silicone does not expand the Teflon. I could be
wrong.
On the other hand I think air may be required to convert liquid silicone
to
the rubber state. That is why they call it RTV or Room Temperature
Vulcanizing
I think.

These picture you attached look like very poor workmanship was used to
make
these O-rings.
I have never seen a TES O-ring that looked anywhere near that bad
including
the
ones we bought from McMaster car. Creavey quality control on the other
hand
is
excellent. It is on the cool side of the engine as well. The O-rings look
to
be the proper cross section size however. Perhaps they were well under
diameter
and somebody stretched them to fit. If you try to do this one section of
the Teflon will yield while the rest of it remains the same. Perhaps this
is what happened some where along the line.

I have always thought of rubber, and that includes silicone, as being
"compressible".
What has been brought home to me after reading some bad O-ring experiences
years ago
is; rubber is no more "compressible" than hydraulic fluid. Furthermore
silicone expands
greatly when heated. If it is contained in a closed chamber without
expansion room such as an
O-ring slot it will generate tremendous forces. Enough to crack cast iron
and bend steel.
Therefore it is extremely important to have the right section diameter
when
installing
O-rings.

If the O-ring is oversize for the slot the process of tightening down the
tension
bolts will cause the hydraulic force of the rubber to break the cast iron
end housings.
The problem will compound itself when the engine is warmed up to operating
temperature
as the silicone expands.

The last picture is what happens when the TES O-ring is too large in
section
diameter for the size of the slot. You can see that the Teflon was cold
extruded
into the space between housings prior to final torquing of the tension
bolts.
The date on this photo is March 2003.

Paul Lamar ...No rotor no motor.



Now I'm getting very concerned! I've installed these o rings in my 20B and
now I'm wondering if I should tear it down and replace them with factory o
rings. I'm getting very close to my engine installation and would rather
do
it now than after the installation. Do we know of success stories with
these
o rings? Or should I just change them...

Bob Mears
Supermarine Spitfire

Bob,
I installed Creavey TES o-rings about 4-5 years ago. While I've only got
about 25 hours on the engine, there is no sign of leakage to date. We'll
see how things develop. Where did you get your TES o-rings?

Mark St.



 They were installed in my engine when it was rebuilt by Mazdatrix in May 2001.
 The engine has over 500 uninterrupted flight hours on it since then. It has not
 been off the plane since it was re-installed June 2001. I never saw the rings,
 Paul provided them to Mazdatrix on wood formers.

 Perry



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