Stuck Valve in 39 Flathead

G

Gordon Ellis

Member
Cylinder #1 has zero compression. I can see thru the plug hole that one of the valves is operating. I assume the other is stuck open.
What ideas do you guys have to free this valve without removing head or intake manifold?
Thanks for any advice.
 
If it's not the one under the plug hole you will struggle to free it up without taking the head or intake off.
First port of call would be to flood the area with some sort of penetrating fluid.
If that doesn't work it may be possible to snake a bent tool over the valve head through the plug hole, but having never done it, I can't say if that is even possible.
It's also worth noting valves do not like off center shock loads. They like to break.
Get ready to realise you will need to pull something.
I'd go with the intake.
Mart.
 
If you or someone you know has a smart phone you can buy a little camera for about $35 that will let you peek in and take a look.
 
Good advice above. I would first rotate the engine so you are at TDC, power strike for #1.
Pop the distributor cap, which is probably marked with cylinder numbers. #1 is at about 10:00 position or second plug wire socket from the top. At this position, both valves should be closed.
 
I use an allen wrench to hit the valve. Try to hit the center, not the edge. Be carful not to wreck the spark plug hole threads
 
I had a stuck valve on an engine that had not been run in a few years. Put some Sea Foam in the tank and ran the car a few times and it eventually freed itself up.
 
modern ethanol fuel strikes again old fashion fuel made from oil [liquid dinosaurs ] modern day fuel made from what ever to make alcohol of some sort alcohol is a solvent not a lubricant so it washes oil away from valves try using small does of twostoke oil in fuel [about what you would put in a gallon of chainsaw fuel ] to each tank seems to work and doesn't blow smoke
 
Try to get a bit of MMO down the stem of the open valve going through the plug hole, this could help brake up carbon on the valve stem and guide. The Allen wrench advice, suggested above sounds good but do not use excessive force it can bend the valve.
 
I just buy some head gaskets and pull the head. How easy it is to get off depends on how long it's been on there. They can be a PITA. Valve bend easier than most folks think so I don't take chances. It could likely use a good cleaning anyway.
 
I would prefer pulling the intake first. You can get at the actual valve train, not just the head. The big thing is that you don't have to drain the coolant. I find it a messy job to avoid if you can.
 
tubman said:
I would prefer pulling the intake first. You can get at the actual valve train, not just the head. The big thing is that you don't have to drain the coolant. I find it a messy job to avoid if you can.
Click to expand...

X2, You should be able to see most of what's going on through the intake side.
Should be able to pry the offending valve up, thusly freeing it. You can oil the stem from the bottom, a bit.

Karl
 
As stated above, marvel mystery oil works amazing. Pour a good amount in the spark plug hole and let it sit. If that doesn't help, it would seem easier to pull the intake manifold that way you don't have to drain the coolant and you can get a good look at the lifters. Good luck ��
 
If it will run, albeit, with a miss, I would also flood it with MMO or some other solvent for a few days and then run the piss out of it. If that doesn't free it up, you'll either need to pull the intake or heads to free that valve.
 
In my younger days I accidentally broke the head off a stuck valve on an 8BA when trying to push it closed through the spark plug hole, I was careful to try pushing in the center of the valve head only and it still didn't work out. I agree with the others advising you to pull the intake.
 
Charles Thompson of TRW developed the way to weld valve heads onto valve stems that allowed for a lot of valve innovations and saved a lot of raw material in the manufacture of valves. The welded joint is very strong at holding the stem on in the way a valve normally works but not so much strength if pushing unevenly on the top surface of the valve head. If it bends even a slight amount, the engine compression will suffer a lot.

I've had to work some valves a very long time just to free them up let alone keep them from sticking. Flatheads don't have a lot of spring tension acting on those old valves. Since I have all the special tools to pull valves out, I remove the manifold and heads first, then pop the valve assemblies out of the pockets to break them down and clean them up. It's a lot faster than tapping and rotating till they are completely free.
 
If I remember correctly from way back in automotive shop in high school, I was told some valve stems were made with stellite? And if we were to hit that valve tip with a hammer the valve may explode. Not sure if that's true or if the instructor was just blowing smoke up our butts. I never researched it any further but I've always been a little leary of tapping on valves...lol
 
When I see cheap flatheads, if they turn over, I buy em. I still see em at junkyards, craigslist, farm auctions. 2-400 for a motor that turns

First thing, I wanna know what I bought, so it goes in my test stand, squirt some oil in the cylinders, spin it over and check compression. Undoubtably, there will be a couple dead holes from stuck valves.

Gravity pulls down. Taking the intake off to lube a valve that is stuck open would require
gravity to go up to get on the stem thats inside the guide. Not gonna happen, and now you see what a gross mess is usually inside these motors, and you get depressed, and need a new intake gasket to continue the test. Worry about the mess after you hear it run and know what you bought.

I have done about 15 motors like this. Use a spray can with plastic tube so you can aim at the open valve stem thru the spark plug hole. Flood it. For several days. Then get the allen wrench in there, try to tap it down. If no luck...repete. Once it moves it will certainly only go down once, and then stick up again. repete until you win. They will start and run with a couple dead cylinders, so if its stubborn, run it to warm things up and usually you will get it to travel free
 
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I would , if it was mine , remove the intake, check condition of spring , make sure the valve guide clip is still secure and soak and try pulling th valve done . Making sure the cam lobe is 180 away from that valve . While your in there , clean out as much gunk as you can and check other valve springs , keepers etc.
 
cas3 said:
When I see cheap flatheads, if they turn over, I buy em. I still see em at junkyards, craigslist, farm auctions. 2-400 for a motor that turns

First thing, I wanna know what I bought, so it goes in my test stand, squirt some oil in the cylinders, spin it over and check compression. Undoubtably, there will be a couple dead holes from stuck valves.

Gravity pulls down. Taking the intake off to lube a valve that is stuck open would require
gravity to go up to get on the stem thats inside the guide. Not gonna happen, and now you see what a gross mess is usually inside these motors, and you get depressed, and need a new intake gasket to continue the test. Worry about the mess after you hear it run and know what you bought.

I have done about 15 motors like this. Use a spray can with plastic tube so you can aim at the open valve stem thru the spark plug hole. Flood it. For several days. Then get the allen wrench in there, try to tap it down. If no luck...repete. Once it moves it will certainly only go down once, and then stick up again. repete until you win. They will start and run with a couple dead cylinders, so if its stubborn, run it to warm things up and usually you will get it to travel free
Click to expand...


https://www.youtube.com/watch?v=kkHZyjiT_wk&pp=ygUhZmxhdGhlYWQgdjggcnVubmluZyB3aXRoIG9uZSBoZWFk


Hey Skip. Come to find out they will run with four dead cylinders. Maybe the head on the side with the zero compression cylinder could be removed, and a guy could take a small brass hammer and play 'whack a mole' with the motionless valve head. All the while spraying pb blaster on the offending valve with the other hand. Just looks like more fun than an allen wrench.
 
I use transmission fluid mixed about half/half with acetone in an oil can. Very effective penetrant. Better and cheaper than most over the counter penetrants. Real good with broken bolts. Try it with an oil can with a flex head, may just get into that intake valve stem/guide area.
 
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