Exhaust valves keep sticking up

[Flatfisher53]

So I pulled my head off my 1955 Farmall Cub and replaced the head gasket. And in doing so as I was inspecting etc...I would rotate the fan and I noticed that 3 exhaust valves are sticking open...obviously it doesn’t really run like that. So I worked them free and got them all lubed up in the guides...thing will run great for two days, then I go to start it up after sitting a day or two and it won’t run worth a crap...I take head off work the valves loose put it back together same thing runs great then sits a day or two and back to same problem WTH is wrong with this thing lol. I am very mechanical but kinda at a loss. Valves are not loose and I don’t really know what to look for at this point. Thanks in advance

[Glen]

Hi,
If the valves are really stuck, I think you will just have to keep lubing the upper valve stems, and work penetrating oil, and then later oil down the stems, until they work freely enough to work without sticking.
You could also remove the valve cover on the left side of the engine, and spray penetrating oil on the lower ends of the valve stems.
Some penetrating oils don't provide lube later, they are not like oil, evidently. The stems need some motor oil, they also have to be clean enough that they aren't tight in the valve guides.

While the cover is off is a good time to set the valve clearance, they are manually adjusted, using a feeler gauge. If the clearance gets too small, the valves won't close all the way, then it can get burned valves.

Below is a page from the 1955 Cub owner's manual, showing how to adjust the valves.

http://farmallcub.com/rudi_cub/www.clea ... e%2055.jpg

If the valves are not stuck much, you could try using an oil additive, and running the Cub doing some work, warm it up good.

The head bolts need non hardening sealer put on the bottom 1/2" of the threads, when putting the head on. The holes go into the engine water jacket. Without sealer, water can run up the threads, and leak out of the gasket.

[tst]

have you changed the oil? old oil sludges up and builds up slime causing sticky valves, get it hot and dump the old stuff and filter, go out and work it with fresh oil to clean out the old sludge that has built up, can through some sea foam in it also to help clean it out helps also

[Gary S.]

Try the easy stuff first put some Marvel Mystery Oil in the crankcase and gas.

[ricky racer]

[Flatfisher53]

I have pored marvels directly down the valve guides etc...I will change the oil and work them free again. Also does it need to be some special thread sealer or will pipe dope work...I ran out of the high temp stuff I was using but I do have thread dope

[Urbish]

Also does it need to be some special thread sealer or will pipe dope work...

For what? The drain plug?

[Cubfriend]

I think I have seen others recommend Permatex Aviation sealer. They say mix thoroughly as it settles in the can.

[MAGNETO]

Find a proper sized brass bore brush for cleaning guns. Remove each valve, and brush each guide until it is clear of deposits. I had the same issues, and this was the only way to keep the valves free. While you have the valves out, inspect them for bends or pits, use a brass brush to clean deposits off the stems. Liberally oil before reassembly.

[Glen]

Hi,
Below is a pic of one brand of sealer for head bolts.
I use Permatex Aviation Form A Gasket, it is a non hardening sealer.
They sell it at NAPA here in the west US. If you buy one, stir it well before using, it settles in the bottom of the can sitting.
They recommend retorquing the head bolts after the engine has fully heated up, and cooled down a few times. Torque the bolts when the engine is cold.