Hi Guys,

My beloved, well-cared-for OS 1.08 started running very poorly in the air
two weeks ago. Brought plane in. Tweaked and investigated, couldn't find
what was wrong. No compression. Gave up went home.

Finally today I got some time to open it up and investigate further. Oh -
My - G_d! There's no stinkin' piston ring on the engine and it's not inside
the crankcase either! No bits in the bearings (no crunching crumblies in
there either.)

What happened ??? Do these engines throw rings occasionally? Where did it
go? Out the exhaust ??

Engine is about 7 years old and was running better than ever. I baffled.

Anyone with any suggestions about what happened and more importantly, how to
prevent this in the future?

Thank you kindly.
David

"DavidP" <dpando@bellsouth.net> wrote in message news:<LpvIa.12089$Re5.4070@fe06.atl2.webusenet.com >...
> What happened ??? Do these engines throw rings occasionally? Where did it
> go? Out the exhaust ??

The rings are made from iron, and are very brittle. It more than
likely disintegrated, or broke into several bite-size pieces, and blew
out the exhaust. In theory, as the piston goes by the exhaust port,
chunks of the ring could fall out, and the exhaust pulse would send
them on their way. At 10,000 RPM, it would take no more than a few
seconds, at most. If you can't find any of it in the bearings, count
yourself lucky, fix the engine, and go flying

> Engine is about 7 years old and was running better than ever. I baffled.

Murphy's law. When something's been "better than ever," it's moments
from catastrophic failure.

> Anyone with any suggestions about what happened and more importantly, how to
> prevent this in the future?

I don't know if it's even possible to prevent it. Sounds like you had
a lot of time on that engine, so the ring was probably fairly well
worn.

It really seems unlikely that all the pieces made it out without hitting a
port someshere, but stranger things have happened!

Gee, you ONLY got 7 years out of the engine? Cheap Jap crap! ;^)

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com
"DavidP" <dpando@bellsouth.net> wrote in message
news:LpvIa.12089$Re5.4070@fe06.atl2.webusenet.com. ..
> Hi Guys,
>
> My beloved, well-cared-for OS 1.08 started running very poorly in the air
> two weeks ago. Brought plane in. Tweaked and investigated, couldn't find
> what was wrong. No compression. Gave up went home.
>
> Finally today I got some time to open it up and investigate further. Oh -
> My - G_d! There's no stinkin' piston ring on the engine and it's not
inside
> the crankcase either! No bits in the bearings (no crunching crumblies in
> there either.)
>
> What happened ??? Do these engines throw rings occasionally? Where did it
> go? Out the exhaust ??
>
> Engine is about 7 years old and was running better than ever. I baffled.
>
> Anyone with any suggestions about what happened and more importantly, how
to
> prevent this in the future?
>
> Thank you kindly.
> David
>
>
>

DavidP wrote:
>
[snip]
>
> Finally today I got some time to open it up and investigate further. Oh -
> My - G_d! There's no stinkin' piston ring on the engine and it's not inside
> the crankcase either! No bits in the bearings (no crunching crumblies in
> there either.)
>


It sounds like the PRT (piston ring thief) is on the
prowl again :-)

Since you found no debris inside the engine, I'm a bit
more than amazed that you didn't find some damage on
the piston and cylinder ports while the ring pieces
were finding their way out the exhaust port.

DS

Amazed!!! It's unblievable!!! Sounds like a troll... But I guess anything is
possible. Well almost anything. Eddie Fulmer

"Efulmer" <efulmer@aol.com> wrote in message
news:20030620174509.13710.00000784@mb-m25.aol.com...
> Amazed!!! It's unblievable!!! Sounds like a troll... But I guess
anything is
> possible. Well almost anything. Eddie Fulmer

Sounds a lot like a troll lol! My old 1.08 tried to eject a bearing. That
didn't go that well. Boom, dead stick and lots of little metal parts all
over the place.

Shaun Bell

You got me. I've gotten really good gettting rings out, sometimes in flight.
(i take screws out of servos arms and keepers off of coltrol horns too)
The PRT gremlin
<G>

"DS" <"dstaffor[NoSpam]"@calpoly.edu> wrote in message
news:3EF37108.41758F7E@calpoly.edu...
> DavidP wrote:
> >
> [snip]
> >
> > Finally today I got some time to open it up and investigate further.
Oh -
> > My - G_d! There's no stinkin' piston ring on the engine and it's not
inside
> > the crankcase either! No bits in the bearings (no crunching crumblies in
> > there either.)
> >
>
>
> It sounds like the PRT (piston ring thief) is on the
> prowl again :-)
>
> Since you found no debris inside the engine, I'm a bit
> more than amazed that you didn't find some damage on
> the piston and cylinder ports while the ring pieces
> were finding their way out the exhaust port.
>
> DS