John McLaughlin wrote:
 >
 > I just received a used 1990 13B NA engine. Exterior of engine is clean -
no
 > leaks, Turns over smoothly and evidences as much compression as possible
 > hand cranking. 6 ports were not functioning. I removed the intake

manifold

 > to take a look.
 >
 > As one would expect, there is a good bit of carbon and sticky black gunk
in
 > both the main and auxiliary ports. I'm wondering how I should try to
remove
 > the carbon. I'm worried about some of it finding its way into the rotor
 > housing and damaging the seals.
 >
 > The seals feel good as felt through the exhaust ports - travel seems
smooth.
 > I'd like to avoid tearing the engine apart, but obviously need to do
 > something with the buildup.
 >
 > I've heard of using ATF to dissolve carbon buildup. Does anyone have any
 > other suggestions?
 >
 > John McLaughlin

John,

I briefly considered not rebuilding my engine as well, as it looked in great
shape from the outside ('91 turbo II), and supposedly only had 30k miles.
Mike Wills reminded me that this thing was going to be my only engine in an
airplane - for crying out loud.  He was right, of course, and I just thought
of all the money I was saving over an aircraft engine and decided it was
worth a rebuild.

After considering the options, I decided to do it myself following Bruce's
video.  I'm really glad I did, mostly because the apex seals were at min
tolerance.  The water gaskets were also in extremely bad shape.  There was
also a big gouge in one of the rotor housings.  One of the oil pressure
regulators was stuck.

I also had a great time doing it.  I had never rebuilt an engine before and
it was really neat to take the thing apart and finally (well, better anyway)
understand how it all works.  Looking back I highly recommend the experience,
it didn't take all that long and Bruce's video was perfectly helpful.  I also
REALLY don't recommend flying a used engine that hasn't been rebuilt.  If
nothing else, take it appart to get all the grime out of the seal slots
(there was a LOT of it in my engine and mine was good compared to others I've
heard about).  Total cost was about $900 in parts and supplies and took about
me, a bumbler, about 40 hrs working time (counting watching the video over
and over and fretting about what parts to get etc).

Dave Leonard

 
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