Stuck Valve??

[jgerard]

keeps you from smacking it into the top of the piston.

Jason
N43643

[mhorowit]

Frank - it gets the piston out of the way so you don't damage either the piston or the valve.

Also, using the leverage of the prop. to force the valve sounds ideal.

Arn't there a variety of chemicals that desolve carbon deposits? We had a discussion on that when we talked about cleaning plugs.

Finally, that idea about stuffing rope into the cylinder --brilliant idea.


Question--What does having cylinder at bottom dead center do to help loosen the valve?

[alwaysoar]

stuck valve

Jason, Is there a way to remove a cylinder without dropping the exhaust?

Ed @BTV VT
TF 527

[stormman]

hate to be the bearer of bad news boys but unless you have a cam with one inch of valve lift your never going to hit the piston on an A65. You would have to remove the valve spring or break the valve first. Check your valve timing specs. Im not trying to be a smart ass ( which i been reminded several times i am} just trying to keep you educated and on the right track.and not spread false information. Got enough John Kerry's out there! Think about the rope in the spark plug hole! And the banana up the tail pipe for a minute
"Get the Picture? The leader of the pack. " " Rooom Roooom"
Scratch That last sentence , as it will only be understood by the "old farts"

I believe that when you check the valve spec's you will see what i mean , BUT if i have too i will explain further.
As far as the kickback when starting you have to swing the prop real fast or get at lest one impulse mag to start on . It's just a fact of life.
Kevin , old does not always mean wiser. I can think of many wise young "Grasshoppers" in the Tribe and a few not so wise O Gs

A teacher affects eternity; he can never tell where his influence stops. .

BTW i was wrong once. On a galaxy far far away.

[jgerard]

Setting the piston at BDC before compressing valve springs is really just a habit. Not always required, just a habit.

Jason
N43643

[stormman]

And a Good habit at that

[Frank DeBartolo]

Stuck Valve

The exhaust valve of the #1 cylinder is stuck in the open position. We removed the cylinder and the valve is stuck open with the spring compressed. Looking for some comments on what could have caused this to happen. Looks like we will have to remove the valve and send the cylinder out for installation of a new valve and guide. Would like to know what caused this so I can avoid future hassle and expense.

Thanks,

Frank DeBartolo
N43684

[jgerard]

I was told by a old-timer (no offense guys) that had built a gazillion engines over the years that if you plan to run the small continental engines on 100LL you should bore the i.d. of the valve guide to the max allowable limit for a new part. It will never wear beyond that and no stuck valves. General consensus is to use MMO as recommended on the can 4-oz per 10 gal of gas. Or run aviation approved auto fuel.

Jason
N43643

[Frank DeBartolo]

I have been using MMO in the gas and Avblend in the oil and using amounts specified by the manufacturer. I have used 100 LL but have been using mogas which is 25% avgas. My baffles are pretty sad looking especially the rubbers that seal and trap the air. The metal baffles are pretty ratty looking (bent and dinged) and are touching the cylinders especially the #1 cylinder where the metal is tight against the cylinder at the rear where the exhaust valve is located. Could this have been the culprit and does a compression test tell if other cylinders are subject to a stuck valve?

Thanks,

Frank DeBartolo
N43684

[stormman]

I don't think so
. On another note i know guys who always throw in a quart of Moble one when they change their oil and never have had a stuck valve.
On the other hand there's five fingers

[alwaysoar]

stuck valve

I'm not sure you have to send the cylinder out. Our local IA can replance valve guides so I don't think (emphasize think!) it's a big deal. Have you taken the valve out and cleaned up the guide and the valve? It's stuck because there's something on the surfaces. I would do that before you send it out to save some $ and know for sure that it needs to be sent out. Do the easiest thing first. As far as other compression goes, the best way is a differential test, but you can also tell if there's a problem by pulling the prop through (be careful if the #1 piston is hanging out there) and listening carefully for blowby. If there is, you can hear it out the exhaust or carb if it's valves. I think you said in another posting the compression was pretty good (70's) at annual.

Anyway, try the easy things first--it might be no big deal. About the baffling: I don't know.

Ed @BTV VT
TF 527

[jgerard]

Frank-

What rpm do you normally run at? Do you have a cruise prop on the plane? What is the normal oil temp? How often do you fly?

If your prop has too much pitch and you normally operate at an rpm that is behind the power curve you can burn up cylinders, especially if the baffling is shot. Most guys tell me they get better compression, the engines make more power longer, and they have fewer cylinder issues if you swing a prop that will allow you to spin up to max rpm at full throttle in level flight. In other words don't baby the engine, wring it's little neck! The manufactures designed them to run at max continuous rpm for the whole TBO.

Jason
N43643

[Frank DeBartolo]

The prop is a McCauley 7443 metal prop. The prop will produce over 2300 RPMs in a shallow climb at full throttle. With the nose on the horizon (appx 80 MPH on my airspeed indicator that always reads 10 MPH on the ground and in the hangar) the tach says 2300 RPMs. The tach is an old non recording tach so I do not know how many hours really are on the airplane or engine or how accurate the tach is. The engine is supposed to have been overhauled appx 100 hours ago in 2001 but I am doubtful if this is true. This airplane is a good little airplane but the owner was deceptive about several things and for that reason I really do not know for sure when the engine was overhauled. For this reason I am looking for answers so I can address the issues so I can fly the airplane and not have face pulling a cylinder every 70-100 hours to free up a stuck valve. I am willing to install new baffles now and if there are other cylinders that will ultimately foul, pull them now as preventative maintenance. I will be installing a new Mitchell recording tach down the road.

Oil pressure and oil temp

On startup the oil pressure is at appx 45 psi and stays there till it gets warmer. On a normal day 60-80 degree surface temp the oil pressure stabilizes at appx 30 PSI and oil temp at appx 180 F. Over 80 degrees surface temp (85-90 degrees) the oil temp and pressure get a little funny. Temp goes over 180 towards 200 F and pressure goes down to 25-28 PSI after a sustained climb. Then slowly the temp will come down to 180-190 F and Pressure will build up to 28-29 PSI. These instruments are old so I don't know how accurate they are. However the baffles are a great concern to me and I feel compelled to do something about them.

Question: Could my problem be related to heating especially since the stuck valve is the #1 cylinder exhaust valve and the baffling around the #1 cylinder looks bad--especially the rubber part of the baffling. It appears as if it lets air go by and the metal part is tight against the back part of the engine and tightly hugging the #1 cylinder.

Thanks,

Frank DeBartolo
N43684

[jgerard]

Frank-

Seems like you have a good prop, I wouldn't think your lugging the engine. Might as well repair/replace the baffle while you're in there. You should find more info as to why the valve got stuck once the Cylinder is off. If it is heat related there should be some obvious signs of excessive heat around the valve. Look for discoloration. You may have a crack in the head or if the exhaust gasket was leaking it creates a hot spot on that side of the head. I'm confident your mechanic will sort all that out.

I am not positive but I think some of the continental engines have different rockers for the exhaust vs. intake. The exhaust ones have a oil squirter hole or something like that to help lube and cool the exhaust valve stem. If that hold true for your engine make sure the correct rocker is on the exhaust side. Also you want to replace the stuck valve, or all of them with the new stellite valves. Check the log book to see what valves were used when the engine was rebuilt. you need p/n 21479 if you want to run 100LL.

For the rest of the Tribe please feel free to verify the above info.

Jason

[stormman]

Someone probably said this already
put rope in the cyclinder , remove valve spring, chuck the stem in a drill and spay berryman's chemtool down the guide while spinning it with the drill , you can even pull bak on it a lite cleaning the valve seat. It works more often then you would believe and it's a quick fix that lasts alot longer than you might think. Spray a lube spray down the guide before you button here up.
This works if it's sticking in the valve guide which it probably is and if it doesn't i will give you all the money back that you paid me and it comes with a lifetime guarantee. Hell i will double your money back as i never had it fail to work yet.

"If it works FLY it"