M Stuck Valves

Firing on #1 & #4 only, suspect stuck valves on other 2 cylinders.

What is Best/Safest way to Free Up the Stuck Valves.??

WD 40 & let it soak? Rubber Hammer?

Thanks RickA

WD40 NO NO NO!!!!!!!!!!!!! Now ATF is what I would use but PB might also work. If exhaust valves pour ATF right down the pipe if intake that is a bit harder to mess with.

How could that possibly help anything? If the valves are stuck, they are stuck open or there would be bent pushrods and broken rockers. Take the valve cover off and verify if they are stuck. Then put penetrating oil on the valve stems while alternately tapping on the valve stem and prying up on the spring. In stubborn cases you sometimes can go through the spark plug hole and pry up with a screwdriver.

Same idea, Tom. Old likes ATF as a penetrant.

The valves are usually stuck in the stem area. Pouring anything down the intake or exhaust would go directly into the combustion chamber and would never touch the stem. You might as well pour something on the ground. It would be easier because you wouldn't need a funnel. Besides, since the M has an updraft induction system, pouring anything "down the intake" would be like pushing a rope.

If an inspection under the valve cover confirms your suspicions, you're on the right track.

There are better things than WD-40 for loosening them up -- any of the usual potions, ATF, Liquid Wrench has served me well, PBBlaster, Kroil . . . your choice on that.

If your push rods aren't bent, you can tell this after pulling them once you've removed the rockers) then the problem is a valve or valves stuck open. In that case, after a good soaking with your penetrant (a day or two) a little judicious tapping with a 12 or 16 oz. hammer to get them started in the downward direction can help to free them. It may take a heavier hammer to compress the springs, but the point is, reagardles of your hammer size, youu just need a little motions to free it up, and there is to be NO walloping! If you do detect a little motion, then apply more penetrating lubricant and tap some more. The tension of the springs will do the job of working them back upwards.

If the valve is stuck closed, I'd caution against prying up against the caps on the springs. In that case, I'd remove the spring (not easy with the head on!). Before any tapping, you need to turn the motor to get the piston on the cylinder in question to TDC. Happily, this is the same spot for both #1 and #4. With the pistons at the top and feeding through the plug hole, fill the cavity above the piston with all the small clothesline you can jam in there. This will hold the valve up enough to keep it falling so far that you have to pull the head to get it back. Then the valve springs can be removed without a danger of them falling down in case you've misdiagnosed. Once that's done, the same judicious tapping and relubing is called for. Once they've moved down, lube some more, pull them back up and reinstall the springs, caps and keepers.

Once you're confident they're all free, reinstall your push rods and rocker, do a quick check on the clearance and then turn it with a crank or the starter with the ignition off and watch to see that they're all operating.

Rick - First make sure it's not an ignition problem (fouled plugs, broken or swapped plug wires, etc).

If the spark is OK remove the rocker box and check valve action and valve lash on the affected cylinders.

You may find a momentarily sticking valve has caused a pushrod or two to become disengaged. It's not unusual for an M that's been sitting a while (it happens to one of mine the first start EVERY spring).

If a valve is stuck, try soaking it repeatedly with PB Blaster, ATF or your own favorite "snake oil" penetrant. GENTLY tapping/pushing down on the rocker above the valve stem between applications of penetrant will sometimes free up a lightly stuck valve.

However if the valve not work free you'll need to remove the head. And while the head's off check for bent pushrods on the affected cylinders.

Do a compression test on those "non-firing" cylinders. With the engine cranking, check for spark at all the plug wires. Make sure the tractor has a good set of plugs. If there is spark to all the plugs and your distributor or magneto is in good working order, take off the valve cover and see if there are any stuck valves. I had a problem similar to this with my F-20 when I got it and found 3 stuck valves. I was always pouring PB Blaster and oil on top the valves, pryed them up with a large screw driver and tapped them down again. Repeat several times until the valves move freely and do not stick.

Your only about 50 correct since pouring ATF in will in fact get it to the stems just takes time. Yep pulling the valve cover and working the valves helps BTDT many times and I play with stuck engines all the time

Make sure the plug wires are in this firing order on the cap. Hal

2-1
4-3

A stuck valve is a lot easier to loosen than a stuck mind. CAUTION: Do not drink any ATF! Not only is it poisonous but you would have to stand on your head for at least 48 hours for it to do any good.

A comment like yours helps no one and is in fact in bad taste. I tell it like it is and have been doing these tractor engine for decades and know what does and doesn't work.

We puled the Valve Cover & guess what ??

We found both #2 & #3 Exhaust Valves Stuck...

The #2 Exhaust has bent the Pushrod, and #3 Popped out of the Pushrod..

Not sure yet if we have bent a Valve or not,hopefully not.

Seems like you have good access to both Valves thru the Sparkplug Hole.

Once the Valves are Free, might be able to Rotate them to see if they are bent??

Should be able to hold them up to Replace Valve Springs/Caps & Retainers if not bent.

Appreciate All of your input..

Thanks Guys

RickA

My dad was a big fan of Marvel Mystery Oil. We had an old M that would stick a valve occasionally. He would put the recommended amount in the crankcase and it seemed to work.

Gene

They will not be bent, there is nothing to hit at all. They can be lubed up from the top with penetrating, not WD40, oil, then tapping on them will begin to loosen them up. If you end up taking the spring off, put a 2' piece of rope in the cylinder, and move the piston up (by hand crank, not starter) to hold the valves in place. The pushrod (unless cracked) can be straightened out on a good block of wood (carefully) then roll tested for straight. No issue at all, they will be fine. JimN

ya, by the time you guys argue about wd40 or atf i would have the head pulled off valves removed and freed up AND the RUST CLEANED OUT of the valve guides and then lubed up and back together before you get done your patch job.just what do you think that rust left in the guides does.and also you can visually see how the valves and seats are, incase a valve job is due.i guess real mechanics know right from wrong.

You got that right Tom!

Your question was the best/safest way, so here goes.

The best way is to pull the head, take it and $150 down to the local engine machine shop and have them do it for you, while they rebuild it. Pick it up when they call that it is ready, and re-install it on your tractor and the darn thing will magically work just like new! I've done this several times to various tractors and it has yet to fail me. Usually takes less than a week total.

"tom" Is not right about anything.

Great answer. You sound like a real mechanic.

Great answer! You and rustred below sound like real mechanics.

(quoted from post at 15:21:16 06/22/09) A stuck valve is a lot easier to loosen than a stuck mind. CAUTION: Do not drink any ATF! Not only is it poisonous but you would have to stand on your head for at least 48 hours for it to do any good.

Click to expand...

If anybody knows about that - it would be you, Tom
mike

and a thank you to you tom. i believe in doing a job properly.i can grind my own valves, but usually seats and guides are needed so i just take the heads in and let my head doctor do the work. some of the suggestions i read here i know the guy has no clue what he is flapping about.i judge a man by his work not his mouth.