Hangar Flying => Hangar Flying => Topic started by: Bill James on November 20, 2008, 10:09:08 PM
Title: Stuck Valve
Post by: Bill James on November 20, 2008, 10:09:08 PM
In the spirit of Thanksgiving, an EZ Chronicle from the past- Friday afternoon, of a three day weekend. Somewhere in the middle of northern Georgia. I give the engine three more starts hoping it will exorcize itself of the recalcitrant valve. But the valve stays stuck. It had stuck once before at Kanab a few months back, and had fixed itself on the restart. But not this time. Over there in the FBO hangar the two young A&Ps see me pushing the VariEze their way. It’s close to quitting time on a holiday weekend and they waste no time getting out of Dodge. Spraying gravel behind his multi-primered Fiero, one of them sticks his head out the window and yells “The Boss, Charlie, is across the runway. He’ll be back over here pretty soon. The hangar is open, use any of the tools you want.”
The FBO hangar is well equipped and everything is well used. Cool enough inside here. I get the cowls off and start unscrewing some valve covers hoping to save some time on the mechanic’s clock figuring out which valve is stuck. Assuming he does make it back over here. My goose is cooked. It’ll probably cost me the whole weekend, and some big bucks. Bet he owns the motel back in town, if there is one. Bet his brother-in-law owns the rental car agency, if there is one.
During every annual inspection I have a couple of A&Ps stop in to work on the engine a little, set the valves, check the timing, or just look the engine over. I always learn something. Watching this master at work today will make this session one of the best.
Charlie walks in and sets some tools on the work bench. “Stuck valve, huh? I heard it from across the runway.” Leaning past my efforts to remove a valve cover, he puts the palm of his hand on each of the four valve covers. "Here’s your problem right here, number 2." OK…I’m catching on. Stuck valve, no flow, temperature…three hot, one not…he’s done this before.
In the next thirty minutes he says only a couple of words. He moves to the tool chest and purposefully selects several tools. He removes the #2 valve cover and I remove all of the top spark plugs. With the switches confirmed off he pulls the prop through watching the two valves. He puts a finger on the exhaust stem and nods.
After securing the prop to keep it from turning he twists an air chuck into the spark plug hole and pressurizes the cylinder. He puts a pry tool on the valve spring and nods for me to hold it. He deftly removes the valve keepers and sets them and the spring on the bench. He taps on the valve stem with a rubber hammer. It's stuck. He quietly says Yep.
With a wooden dowel he taps on the end of the stem. It moves in and is pushed back out by the air pressure. I think we are both hoping it will free up by just tapping on it and loosening it up. But no go. He gets it to move a couple more times but it is sticking. With the wood dowel he taps the valve and it falls clanking into the cylinder. I catch my breath.
It’s Friday afternoon of a long weekend. The valve fell in. We are going to be pulling a cylinder. His brother in law surely owns the car rental place. Dollar signs ratchet across my eyes. No way I’ll be meeting the family in Fort Payne today. Maybe not even tomorrow.
But he doesn’t miss a beat. It doesn’t seem to bother him at all that the valve fell into the cylinder. He is rummaging around in a small drawer, looking at one drill bit and then another. Turns out they are “reamers.” He trial fits several of them into the valve hole, selects one and chucks it in a drill. He takes a stance beside the engine, positioning his feet and crooking his neck around like a batter at the plate. He deftly positions the drill and gently works the reamer in and out of the valve hole. He extends one pencil magnet and slides it down the plug hole and slides another extended magnet in through the valve hole. He fishes around for a half minute or so, then delicately, with his little fingers up, magically pulls the valve into position, one magnet pulling the tip into the hole and one magnet lifting the stem. Spectacular. I start breathing again.
He pressurizes the cylinder and taps on the valve stem. He unhooks the air hose and pushes on the stem with his finger. No smile yet. He finds the wooden dowel and taps the stem once, twice, three times, and the valve clangs down into the cylinder again. Good grief. And I thought we were out of the woods.
He picks up the drill, repositions in his stance and gently reworks the valve hole a couple of times. He inserts the two pencil magnets into the cylinder and works them around and glides the valve up into place again. With the cylinder pressurized he taps the stem with the rubber hammer. The valve moves in and out. He takes the air hose off and pushes the valve stem in with his finger and pulls it out with the magnet. Nice. He smiles.
With the cylinder pressurized he positions the spring compression tool and nods for me to hold it. He slips in the spring, washer and retainers. Replacing the valve cover he says, “Do you need a receipt?” I say no. He says “That’ll be fifty bucks”. Dinner in Fort Payne is good. As is the valve, from then on. Michelangelo lives.
Title: Re: Stuck Valve
Post by: flyingwaldo on November 20, 2008, 10:30:43 PM
Glad to see you back here Bill. Your posts are really good to see again!
Title: Re: Stuck Valve
Post by: Bill James on November 21, 2008, 08:08:27 PM
Thanks, good luck with the motor-
Title: Re: Stuck Valve
Post by: GlennBob on November 22, 2008, 09:24:44 PM
Wow ! !
Bill, . . .that WAS pretty cool. Who'da thunk it ? ! ! I'da thought you'd be pullin' a jug too ! !
Nice blow by blow ! ! Michelangelo ? ? Yeah . . I guess that was art work ! ! An cheap too ! !
Glennbob
Title: Re: Stuck Valve
Post by: Radioflyer on November 23, 2008, 03:10:20 PM
Nice writeup as usual, Bill. This is Ye Olde Rope Trick except done with compressed air instead of a rope to temporarily hold the valve. My question is How come I'm never so lucky to find a mechanic who both knows his stuff and charges a reasonable (i.e., non- "opportunistic") price?
By the way, the best internet pictorial I've managed to find on this method is at http://www.theleftseat.net/stickyvalvereaming.html
In my case, I wish there was such a pictorial for the "Wobble Test" which would diagnose impending valve sticking or valve guide wear before it became a problem.-
Title: Re: Stuck Valve
Post by: GlennBob on November 27, 2008, 07:51:16 PM
Boys,
Be careful about putting rope in your cylinder ! ! This is NOT a terrific idea. It can put uneven pressure on the piston and could damage or bend the face of the valve ! ! Compressed air is a much better option. This procedure looks like a time saver though.