The Stovebolt Site Forums The Shop Area Engine Shop 1946 216 with Stuck Exhaust valve

Hi, I am trying to get a 1946 Chevy pickup I just purchased running. The motor turns freely, but when I popped off the valve cover I noticed one of the push rod's was missing. Needless to say, I ordered a new one, but upon placing it into position and turning the engine over by hand, the stuck valve did not want to give!

I have read all over to put Marvel Mystery Oil on the valve and tap the top with a hammer. Not sure if I should be hitting the top with a lot of force or gently tapping (so far it has been gentle) I still have not been able to break it free. The last time the truck ran was in 1956! Should I drop the oil that is in there? There appears to be lots of sludge, in the upper part of the motor. I also put my finger to plug the spark plug holes, all but the cylinder with the stuck value blew out any air, I am not sure if this would be correct. Also, I assume if the Intake valve is moving on that cylinder the piston should still be good?

The cylinder is the one closest to the water pump.

Should I remove the head? I am trying not to, as it appears to be a lot more work.

Any other ideas or thoughts would be greatly appreciated.


Thanks in Advance, Chris

You need to get a good penetrating oil and put the straw in between the valve spring coils and spray the valve stem. It take a little bit at a time. You might also want to take the rocker arm off the valve, then use a small piece of wood on top of the valve stem and give it a good whack with a heavy hammer. Do this a few times then go back and start spraying the valve stem. If it moves a little don't get carried away. Keep spraying and working it.
Good Luck Don

Chris,

Sounds like a neat find. Any pictures?

It does sound like you might have an engine with a significant problem. There must have been a very good reason for the pushrod to have been removed. I would guess that the vave must have siezed up while the engine was running. Certainly whoever removed the pushrod would have tried to unstick the valve.

Anyway, you could loosen the adjuster on the intake vave for number 1 cylinder (cylinder closest to the water pump) and then rotate the engine with number one plug out, and see if it will draw air in on the intake stroke, and out with the compression stroke. That may be enough to tell if you have a hole in the piston or a broken off valve head. You could also apply compressed air at the spark plug hole and see if it will hold any pressure.

Although you don't want to do it, I would advise taking the head off and give a look see. It is easy to do, and if all is OK, it will just be the cost of a couple of gaskets.

It would also be worth your time to drop the oil pan and check out the lower end. At least you can clean out all the gunk.

Good luck, and let us know what you find out!

Kurt

You can try lots of quick fixes or you can do it right. Pull the head and fix it right. I stuck several intake valves shut on my '38 by using old gas. I ended up pulling the head and driving the valves out. A good cleaning (head and gas tank) solved the problem for me.

A valve that is stuck too tight to respond to penetrating oil and some gentle tapping probably needs more attention than you can give with the head in place. Even if it frees up somewhat, there's a danger of damage once you get the engine running. I'd suggest pulling the head and let a machine shop do a good cleanup and a valve regrind.
Jerry

Thanks for all the advise, I went ahead and started removing items to pull the head. After reading the responses it sounds like the best approach.

Currently, I am trying to figure out how to remove either the fan or the water pump. I removed the four bolts holding the fan, but it does not want to come loose. I was also able to pull the thermostat housing and upper radiator hose off. Any advise would be greatly appreciated.

Thank again, Chris



1946 Chevy pickup picture

The fan is a tight fit on the hub, especially if it's been there a long time. Soak the area with penetrating oil and wiggle the fan blades side to side to break the rust loose. Be careful not to bend the blades or gouge the radiator fins- - - -it's pretty close quarters in there.
Jerry

If you want to remove the waterpump, remove the radiator first.

I don't think you have to remove the waterpump to pull the head. It is attached to the block, not the head.

Do you have a shop manual? If not you might want to review the online shop manual info at the

Old Online Chevy Manuals project.

Here is a link to the section of the shop manual about removing the head

Removing the head.

Good luck!

Kurt

Also how do you remove the temperature sending unit from the block? It appears to be soldered into the connection on the block, or it could just be stuck! Is there a trick to getting it out?

Once the threaded nut with the square head is removed, the temp sender bulb should lift out. Be careful not to flatten or break the capillary tube- - - -it's not a solid piece, it has a tiny hole in it that goes to the dash gauge. Penetrating oil and carefully wiggling it with pliers usually loosens it up.
Jerry

I guess you mean how do you remove the temp sending unit from the head? There should be a fitting over the sensor that you unscrew. Do be careful, it is a soldered connection to the tube that is in the head. If you open the tube, then by by gauge.

Dig around right at the head. You should find something you can put a wrench on. make sure the sensor does not twist with the fitting.

Kurt

Still stuck on the sending unit, I was able to get the square head loose, but it doesn't want to come out. I put some penetrating oil (mixture of ATF fluid and acetone) on it and will leave it over night to see if it will do anything tomorrow.