Chuck Dunlap wrote:
I just took apart my 13b after replacing it with my
spare. I removed
it because it was low on power and blowing oil out the breather
tube. I found the front rotor overheated. The front face was the
worst, the side seals were partially disintegrated and totally
seized in their slots. The oil seal O-rings were
completely gone on
that side, only part of an O-ring remained on the rear face.
The cause was a piece of silicone sealant stuck in the E-shaft
oiling jet, blocking oil cooling to that rotor. I had
modified the
jets by removing the ball and spring and installing a
smaller Weber
jet. This was a bad idea, I think the spring would have
acted as a
filter and kept the debris out. The offending debris came
from too
much sealant used for the stock oil filter bypass plate. Second
lesson learned: Don't use silicone sealer anyplace after the oil
filter. Or at least use it very sparingly.
Paul Lamar responded:
Amazing you flew that airplane all those years with this problem.
Eh? How do we know when the silicone sealant debris obstructed the
oiling jet? I'm not saying that it happened only 15 Tach
minutes ago,
but how do we (or at least Paul) know when it happened?
Russell Kent
Chuck has been noticing something wrong for years. In fact I
probably got a ride in the airplane back when it was
suffering from this problem. I assume the silicon was used
when the engine was assembled for the first time. Jerry Hey
got a ride not too long ago when we did some airflow
measurements on Chucks cooling system so the performance was
not all that bad. I drove my Cosmo with shot oil O-rings for
about ten years.
Paul Lamar
Here is a brief history.
Sep 2000 First Flight, engine #1 straight from wrecking yard.
Oct 2000 Paul flew with me at Copperstate
Jan 2001 Replace with engine #2 which I built. Engine #1 had 80 hours on
it, using oil due to overheating from insufficient oil cooling.
April 2001 Flew to Sun-n-Fun
June 2001 Flew to Seattle
Feb 2002 Flew to South Dakota
July 2002 Flew to Oshkosh. Engine was using oil again but ran just fine.
October 2002 Swapped engine #1 back in after I rebuilt it. Engine #2 had
160 hours.
Engine #1 now has Paul's TES oil O-rings and 2 piece apex seals I got
from Hans Conser
I flew it last Sunday with the new engine - power is better, 5600RPM
static.
I Might be able to fly it to Copperstate if Tracy can help get the EC1
programmed. It won't idle.
I have made gradual improvements to the oil cooling and it is not a
problem anymore. Hard to tell exactly when the oil obstruction occurred,
but I am sure it was obstructed before the Oshkosh trip. That rotary is
one tough little motor. Of course I would not have taken it to Oshkosh
if I had known about the obstruction. We need a good compression tester.
Seems like the only way I could have detected what was going on. When it
happens gradually it is hard to notice, especially when other things are
getting changed/improved.
Chuck Dunlap
If we had a PIC data acquisition system we could use it with a high
speed pressure sensor to get a plot of compression. Ed is doing
some PIC programing and this would be a piece of cake for Ed
and a PIC. Put me down as the first customer Ed. Dump the data
to PC through as USB or an RS232 serial port. Same thing would work
great on exploring pressure waves in tuned intake manifolds.
Paul Lamar
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