On friends, old airplanes, and #3 exhaust valves

The verdict is in on the rough running engine in my J-3 Cub - the exhaust valve on the #3 cylinder fails to seat properly. Just why is a mystery for Lee to divine, but after a week of head scratching and hypothesizing, Russ and Stu and Bill and Bob and Bill and Mike and Steve all pitched in and we found the problem. I wrote George, who flew with me when I brought the Cub to NY:

Hi George ..Well, I went out to the airport and fired up the Cub last weekend … engine ran rough. I couldn’t believe it. It felt like the motor was running on three cylinders, it was shaking so badly … There was a lot of muttering and mumbling on my part … the cylinders all felt the same compression-wise … It really felt like there was a miss, but at the same time it could have been an out-of-balance prop (although I store it horizontally) or some other goofy thing. It was the same on each magneto … On Monday I went out and pulled the lower plugs and cleaned them and that seemed to help a little, but only marginally. I’m going to pull the upper plugs over the weekend. The airplane has been sitting for about 3 months while I decide What To Do With The Rest Of My Life and I can see now that letting it sit is probably not a good thing to do. The engine rebuilder guy is all for the plugs – I am completely mystified. Cold up in New York today ... blah blah blah ...

George wrote back:

I believe that airplanes are capable of sulking when they are given insufficient attention by their owners. In this case, though, I’d look at plugs. You did exactly what I’d have done. The other malady that comes to mind, regardless of the apparent compression, is a stuck valve. Can you pull the rocker covers and have somebody prop it while you observe? ... Cheers, G

After glossing over that crack about insufficient attention we scratched our heads and after Russ waved the magic wand I wrote again:

The problem has been diagnosed – partly. At least we know which cylinder it is and maybe part of the cause. You got it – stuck valve. The telephone diagnosis was coke in the valve guide but then my ol’ buddy mechanician took a closer look and it might be more than that – even to a cracked cylinder. So tomorrow off comes the jug and it’ll be shipped maybe to Superior for a closer look. We worked through it all, and without any contesting and everybody finally agreed that the way to do it is the right way. We’ll all end up feeling good about it (if the engine proves good when all’s said and done). What was really strange was that the cylinder held pressure when we checked it the first 2 times … then when we ran it for about 2 minutes with the rocker covers off (what a mess) – just enough to put a little heat in the cylinder – we hand propped it through all 4 and the prop swung right through what turned out to be #3. Pushback into the hangar and tried the pressure gauge again and it held pressure again … backed off the prop a little to unseat the valve and WHOOSH that was that – the valve never re-seated. I can’t tell you what a relief it was to find a specific problem that made sense. Let’s hope the problem turns out to be the cylinder – if it’s tappets, we’re going to have to split the case again. Newly rebuilt engines are new to me – I prefer airplane engines with a couple of hundred hours on them if they’ve been treated well. … Our trip to Hville is going to be another quickie – enough time to be struck dumb by the mess and then back before the Christmas traffic gets ghastly. On the way back, we’re thinking of overnighting at Broxton Bridge Plantation near Ehrhardt … the owners have a little over 7500 acres with an airstrip, meeting house, B&B, fishing hole, shooting, and horseback riding … a real find, if what I read on their website is anywhere close to accurate. I always wanted a plantation. You and I could sit on the veranda, listen to the crickets and the bullfrogs and make friends with a condensation-beaded glass of something cold.

>>>>TODAY WAS THE DAY<<<<

... and here's what I tacked on to my last note to George:

Well, Geo … it was partly the valve (fixed today) and partly an out of balance prop. So we were both on the money. I couldn’t believe it – after pulling the cylinder and cleaning the valve seat and guide, the engine still was a little shaky – not running rough, just shaky. AT LEAST PART OF THE EQUATION WAS SOLVED. (CAPS LOCK off). So Russ pulled a metal prop out of his hangar and bolted it on – the engine is smooth as glass. Just in case the problem was really fixed and the prop change was an illusion, we re-mounted the wood prop and it shook again … remounted the metal prop and it was smooth. Pretty solid evidence. So the wood prop that looked so nice and felt so comfortable in my hand when pulling it through is in the back of the car and will go with us to Florida – by car now instead of Southwest Airlines. More on that. Last week when we flew back up to NY, I had a little ear blockage in my right ear – no biggie, this has happened before and resolved in a few days. This time it didn’t resolve and I’ve had a middle ear full of gunk for a week. No real hurt, but uncomfortable, if you know what I mean. So I went to my local ENT guy who couldn’t see me but another doc in one of the other offices could so I saw him – we didn’t speak the same language but he supplied me with the meds I already knew I needed from my research (on the internet, natch) and I finally got in to see my real doc today – he said no fly, flyboy, so that’s the best excuse I could have gotten – a gift, actually – to drive and take my prop and a couple of rifles and whatnot at the same time. Life just keeps on happening no matter what plans you make … ain’t it a kick?

And that's how my week has been.