Just wanted to share my adventure from yesterday - below is an excerpt from my post on the Yahoo Stinson forum and ISC forum, enjoy...
Long story short, while on climb out from W91 (Smith Mtn Lake, Va)
there was an alarming shudder from the engine followed by a noticeable
loss of power. I was departing the pattern from the left downwind of
23 and was maybe 1500' AGL.
I immediately dumped the nose and maneuvered to get aimed back at the
field. Once I rolled out I eased the nose up to capture best glide and
aimed about 1/3 way down the 3000' runway. I still had the throttle at
full but the engine seemed to be making very little power. I broadcast
my situation and intentions on the CTAF. A Cherokee 180 who departed
right behind me called me in sight and said that he would keep an eye
on my from above.
With increasing confidence that I could make it all the way to the
runway (if I didn't make the runway it would have been trees) I pulled
the throttle smoothly to idle to see if there was any response. There
wasn't much change so I left it at idle. Once I was confident that I
could make the runway I shifted my aimpoint closer to the approach
end, brought in the first notch of flaps, and maintained my speed.
Rolling out on final I began S-turning to work off a little bit of the
altitude and then brought in the second notch approaching the numbers.
As I touched down the prop came to a complete stop and I just rolled
down the runway in silence.
It just so happened that the owner of the one residence on the runway
happened to have his handheld turned on while knocking around his
hangar and heard my call. On rollout I saw him come racing out to the
end of his taxi way and wave me in. With just enough energy left to
make the turn I coasted to a stop on his ramp. Whole adventure start
to finish was maybe two minutes.
Next came the trouble shooting. We started with fuel - everything was
fine. Good flow, clean gascolator, clean bowl on the carb. Everything
looked secure on the engine so we were stumped for a moment. Phone
calls went out in a frenzy, each of us calling our IAs. In the midst,
for kicks, I moved the mixture and throttle while he watched on the
carb. As I pushed the throttle to full we heard a clunk as something
fell out of the carb into the airbox. Pulled the cowl and inspected
the air box - found a nice little chunk of metal that, at first guess,
looked like a piece of a valve!
Next we pulled the prop through to feel for compression - there was,
not surprisingly at this point, a dead one. We pulled the plugs and
confirmed it. Upon removing the exhaust we heard more metal parts
clacking around inside the heat cuff - more valve parts. So there were
valve parts in the intake and exhaust, not good. Off came the cylinder
and we got our answer - exhaust valve and guide gone and piston
punched through. Copious metal throughout the top and bottom.
My engine (Franklin 165) was built by George Heinly years ago but only has about 200 hours on it. I have flown most of that in the two years that I have owned the plane, so it sat for quite some time after he built it. I am religious about running MOGAS, and when I have to use LL I add TCP. I have read about the problems with the steel guides, but I though that my relatively frequent operation would have prevented issues there.