VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Stuck valve

I am restoring a 32 chevy. Staring with a rolling frame with engine, trans, rear end. But it has set for years. I am getting things moving again, but have one stuck valve left. I have soaked it with WD40, and buster, tapped it with a plastic mallet. I have heard of and will get "Kroil". What do you suggest next?
Thanks

just keep giving it shots of a rust buster penetrating fluid. It will break down, tap with plastic ended hammer. Just don't bash it with a heavy hammer. Unless you want to replace all the valves.

A shot of trans fluid should also help.

good luck

mike

A brass drift is much better than a plastic hammer. Produces a stronger force than plastic and will not mushroom the end of the valve stem. PB Blaster is the best penetrating oil I have found. 50-50 ATF in Acetone also works well. If after a few days you don't get the valve to move then remove the valve spring and apply some heat with a propane or MAP torch. You can use Oxy-Acetylene but sparingly (easier to do damage). It will eventually break free but it will likely be necessary to remove the head to get the valve to move back up. If you can get the valve to free up with the valve spring installed in most cases it will eventually bring the valve back to a close position. A quick compression test can determine if you need to remove the head and grind the valves. You can also used compressed air in the spark plug hole to test for leaks.

What causes this and how is it avoided in the future?
Thanks.

Old gas forms a varnish on the lower part of the intake valve stem. I try to not let my gas get over ayear old. Also add some 2 cycle oil to the gas before winter. A good brand of 2 cycle oil contains a fuel stablizer. The oil pre lubs the cylinder walls and intake valve stems when you start the engine in Sping. Also I never start the engine all winter and keep the gas tanks at about 1/4 full if possible.
Pouring some Marvel Mystery oil through the carb. throat with the engine running may also help (in Fall) That lubes the inside of the exhaust system as well.

Hello chevtrkmn,
I believe that sticking and stuck valves are caused by carbon buildup and/or varnish on the valve stem near the valve guide, eventually keeping the valve from seating fully, thereby promoting poorer combustion and accumulating more carbon. Little to no oil to the rocker arm and above the valve guide isn't helpful either. Your efforts are trying to soften and shed off the buildup to get the valve to come up and seat. With the piston on the compression stroke, both valves should by seated. If the stuck valve has it's valve spring fully compressed, there may not be any gap to work the valve up and down by taping with the hammer. An old trick used then and now is to remove the spark plug, lower the piston to bottom of stroke, feed clothes line rope into the cylinder to fill it, leaving a little hanging out the hole for retrieval. Rotate engine to bring piston up, pushing rope against the open/stuck valve to try and raise the valve some. You may be able to work both ends of the valve that way. Steady pressure only, don't slam the piston and rope or you may damage valve. Using good fuel, clean oil and proper timing should reduce those issues in the future. Good luck.

Thanks for the info. I have this problem with my intake valves on my 1938 1/2 ton. Exhaust seem to do OK. I am hoping they will loosen up enough without me having to remove the head.

Pour some MMO or ATF through the carb. with the engine running and dround the engine out and let it sit for a day. May help.
Don't forget to turn of the igniton.

All my intake valves are stuck or sticking and the engine will not run. I am spraying the valves from the top with blaster. They move now, but stick open and I think I don't have enough compression to run.

Hi,

Since the valve is stuck, try removing the spring, the spring cap and key. Then I use a tap handle (the T - handle that comes in a tap and die set) and tighten to the top of the valve stem above the key hole. Now you can gently turn it and it might break loose. Once it is loose you can apply upward force while turning it, and if there is light carbon build up. it will clean up quite nicely.

Also, it is not a long job to remove the head, so don't worry if you have to resort to that.

Good luck,
Blaine

This looks like they are really stuck and removing the head, cleaning the stems and grinding the valves will be best in a long run.

If the car has been sitting for a long time it's probably a good call to remove he head. Unless you know the condition of the valves and seats. If you have the body off and you are working on the bare frame take as much as possible off the engine clean what you can re-gasket everything roll the engine over and measure the cylinder bores.Get a dial indicator measure the end float on the crank. Sounds like a lot of work but a gasket set is $150 or so money well spent. Oil leaks are a pain and will make a mess of your nice paint job. Knowing some of the internal clearances in your engine will help later on in troubleshooting strange noises. Taking the pan off and removing the side cover will allow you to clean out any sludge that will cause problems latter on .Take lots of pictures before you start. Take your time it's not a race it's an adventure .

Thanks all. I am the one who started this conversation question. In the end I freed up the valve by first tapping it down about 3/8" with a brass rod and small ball pin hammer. But it did not come back up by the spring. So after much blaster etc. it still did not come back up. So I pushed about 25 feet of 1/4" of nylon rope in the spark plug hole (as suggested above), and used the piston to bring the valve back up. After about 20 up and down it freed up. Next to test compression and run the engine to see if they all seat.

Be careful... This is what my '36 did last summer... and after freeing up 4 valves I ran the engine for about an hour and it sounded good... Then the next day two of them FROZE AGAIN.

My suggestion is to run your engine for at least 3 or 4 hours, with the valve cover off, and spray the valve guides repeatedly with oil, or penetrating oil during the 3 or 4 hours.

And after you turn it off, spray all of the valve guides with some oil too.....

One other thing -- make sure that you don't have rubber boots inside your valve springs. That prevents the oil from going down the valve stems.

Pouring a light oil through the carburetor throat with the engine running at a fast idle will get the oil directly on the lower part of the guide and valve stem where the varnish is.

Yes yes yes... I forgot that part. Thanks Gene.

Ya gotta lubricate the LOWER part of the valve stems -- before the engine cools off.... This is a good thing to do after it's warmed up.. and then again just before you turn it off.