Beech C23

[Big Chip]

This definitely qualifies as “other vehicles”. It’s a Beechcraft Sundowner with a Lycoming O360.

I’d been having an intermittent rough running issue that was a bit of a problem when you’re trying to climb out. It happened twice on missed instrument approaches, thankfully simulated approaches. After doing a low pass and adding power to climb it would go rough and feel like it was going to shake the plane apart. It cleared up the first time and second time went back, landed and played with it until it cleared up.

The original thought was the “sniffle valves” that are part of the intake system. We assumed they were sticking open and creating a huge intake leak. They are designed to let excess fuel out of the intake and when the engine starts it sucks the valve closed to seal the hole.

I finally got it to do it on the ground so I put plugs in place of valves. It didn’t fix it. Took #2 rocker cover off and found this:

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Hard to see but the exhaust valve is stuck wide open.


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[Big Chip]

We did a compression test and found #3 was at 54 so made the decision to buy 4 new cylinders.

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Made the decision about the cylinders based on the condition of the cam.




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[Big Chip]

Needed a new crank seal too. The old one was spinning in the case.

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I had removed the old seal and spent probably an hour cleaning up the home. There’s about an inch between the prop flange and the case. At least this flange has holes in it to work through, some are solid.


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[Big Chip]

This is the plane, by the way.

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It was in for an annual in this picture. I’ll probably do the annual inspection along with the cylinders even though it isn’t due until The end of January.




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[1987 GMC Jimmy]

Something similar happened to my dad when he had a Continental IO520 swapped into his '62 Beech P35. I think he lost a cylinder or two right as he took off even though it did fine with the run up, and this happened right above the treeline with too much runway gone to abort safely. He barely had enough power to keep it above stall and maintain altitude, but he took off over a swamp so if memory serves he just turned wide until he had his heading right and shot for two or three airports directly between home and the mechanic FBO. He said it cleared up little by little and he was able to bypass each emergency landing airport to make it home, but if it had lost more power, it wouldn't have been so good. I think that flight is around 90nm... Besides that incident, that Bonanza was the best plane. Him, my mom, and I flew in it from Brookhaven, MS to Sacramento, CA back in 1999, and it did great. He sold it in '02, but I really miss that plane. He did, too. He bought a wrecked B55 Baron in '99 that he fixed up himself, which had a nose gear collapse in 2008 and got totaled, and he had an A36 Bonanza that he bought in '04 and lost about fifteen months later in Hurricane Katrina. Then there's at old 210, which was the last plane he bought. If I could get my hands on that P35 someday, I would. As far as I know a lawyer in Montana owned it, sold it, and it's just sitting unregistered somewhere in the Pacific Northwest collecting dust.

 

[Big Chip]

He was definitely on the right track with the Beechcraft! We do the maintenance on a lot of Beech. A few Barons, a few Bonanzas, a couple Sierras and several Musketeers. I think they’re the best built planes but they sure are a pain in the ass to work on!

The IA I work for says h s never seen a stuck valve in the 25 years he’s been working on these things but the old guys all have a story about it. When it stuck I thought it was a fuel issue, water or debris or something because it cleared up in short order.

This engine has about 1000 hours on it and it has overhauled, chrome cylinders. I had to lean the thing pretty good on the ground or I would get rough mag drops because of the oil soaked bottom plugs. I’m hoping that problem is gone after this.


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[Big Chip]

New cylinder and piston

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No cylinders and cleaning

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[Big Chip]

Started hanging cylinders today

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I’ll hang the last one tomorrow when I have some help and get everything torqued down. There’s through-studs that are easier to torque correctly with assistance.

 

[1987 GMC Jimmy]

He was definitely on the right track with the Beechcraft! We do the maintenance on a lot of Beech. A few Barons, a few Bonanzas, a couple Sierras and several Musketeers. I think they’re the best built planes but they sure are a pain in the ass to work on!

The IA I work for says h s never seen a stuck valve in the 25 years he’s been working on these things but the old guys all have a story about it. When it stuck I thought it was a fuel issue, water or debris or something because it cleared up in short order.

This engine has about 1000 hours on it and it has overhauled, chrome cylinders. I had to lean the thing pretty good on the ground or I would get rough mag drops because of the oil soaked bottom plugs. I’m hoping that problem is gone after this.


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I'd be a little concerned with that mag drop, but like you said, it'll probably be gone now. It's coming together, though. I think they're the best built planes, too. You can just look at them and tell that the design and workmanship rivals a Cessna or a Piper, or at least that's how I feel. I've never been around the Sierras and Musketeers much, but I know it takes a lot of patience to work on all of them. I remember my old man replacing the fuel bladders on his B55, and that seemed like quite a job. He actually trailered that thing home from a salvage yard in Atlanta (tornado damage), which is about 6+ hours from where I'm from on two rinky dink borrowed trailers. He put it back together, replaced or overhauled what was needed, and painted it himself in his hangar. He paid a local A&P in Mexican food to sign off on his work, but I know he did a lot himself after it was together and going.

 

[Big Chip]

This is the problem with the rough mag drop:

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There was a fair amount of oil fouling on the lower plugs. If I leaned it when I was taxiing it was fine. I could clear it up by running it up and leaning when it was on both mags until it stumbled. A couple times and the drops were smooth again. I’ve known for a while there was a bunch of oil getting by the rings but as you know they don’t give airplane parts away.

Your dad sounds like he was a very ambitious man by the way! Kudos to him for undertaking those projects.




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[Honky Kong jr]

This is the problem with the rough mag drop:

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There was a fair amount of oil fouling on the lower plugs. If I leaned it when I was taxiing it was fine. I could clear it up by running it up and leaning when it was on both mags until it stumbled. A couple times and the drops were smooth again. I’ve known for a while there was a bunch of oil getting by the rings but as you know they don’t give airplane parts away.

Your dad sounds like he was a very ambitious man by the way! Kudos to him for undertaking those projects.




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Only problem I see is, that 7 of them plugs aren’t as well lubed as the one is. Lol I tried to stay out of this one damn that was hard....

 

[Big Chip]

Only problem I see is, that 7 of them plugs aren’t as well lubed as the one is. Lol I tried to stay out of this one damn that was hard....

The #4 lower plug came out really easy! The surprising thing is that wasn’t the cylinder with the low compression. We use a differential tester for these engines so we run everything at 80 psi as the baseline. #4 was 74/80. #3 was the low one at 54/80 and those plugs were not too bad.

I don’t know if you can see the numbers on the plug tray but we put them in the tray in the position they come out of the engine so we can monitor the cylinders and when we clean them we rotate them. So #1 top would move to #2 bottom, 2 bottom to 3 top, etc. there’s a couple different ways to rotate but that’s what we do. Plugs are generally good for about 500 hours or so. We clean them, gap them and do a resistance test on them if they’re suspect.


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[Dooley]

Squares and Beechcraft go well together!

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[Big Chip]

I love Beech 18’s! That’s one of my favorite planes. Is that you tugging it?


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[Big Chip]

Hold downs nuts, piston pin end caps, cylinder base o-ring

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The last time these valves will look like this:

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