Next steps after freeing stuck engine

[JoeyO]

So, my 56 cub came home with a stuck engine. Sat outside with an open exhaust pipe. Fortunately for me, the VERY awesome Dale Finch lives fairly close and has helped me get to where I am. After soaking the cylinders in mystery oil, we pulled the head off. I was surprised the bolts gave me no trouble. #2 cylinder was rusted. A few love taps with a block of wood (patience is not a virtue of mine) and the engine is now free. 2 valves also need coercion which makes me nervous. A local tractor mechanic suggested I pull the one piston out and soak it to see if the rings are frozen, hone that cylinder and put it back together. Does that sound right? Should I pull the two valves and have them checked? Thanks for the help.

[SamsFarm]

Or you could take the minimalist approach and lube the stems of your stuck valves, work them up and down till they do not stick anymore, put it back together, start it up and drive it around.

Put some seafoam in the gas and oil as directed.

None of us (except maybe Dale) know the exact condition of your engine!

[staninlowerAL]

Freeing the stuck valves is not too difficult as noted. My opinion is to go a step further while you have the head off and check the condition of the valves and seats. If they are not sealing properly you will have to go back into the engine to correct the problem later. While you have the engine open is the best time to check and correct any problems with the valves.

[ricky racer]

You've got some of the best help available right near you! That's a good thing, Dale's a wealth of knowledge! I guess what I'd suggest is, keep in mind you're working on an engine that is 66 years old and it's likely there is some wear to be concerned with. I'd measure the bores to see if they are in spec. With 66 years of use it's likely been bored out so you need to verify the bore diameter. If the bore is in spec either standard or bored out, that's a good thing.

With the piston out, remove the rings and place one of the rings into the bore and square them up by inserting the piston to push the ring a bit to make sure it's square with the bore. Measure the ring end gap with a feeler gauge. Do this first about 1/2" down from the top of the bore, then again at mid-bore. Any difference in end gap measurement in the two different positions will indicate the condition of the bore. What you find regarding the bore measurements and bore condition will likely be somewhat representative of the condition of the rest of the engine bores. If everything is within spec, myself, I'd probably remove all of the pistons, clean them up and fit them with new rings, run a ball hone through the bores to add a new crosshatch pattern. Clean the bores out good and reassemble the pistons. I guess while you're at it, inspect the rod bearings and check their clearance with plasti-gage. If all is good, continue with your reassembly.

Regarding the stuck valves, remove them and give them a through cleaning and check the fit in the valve guides. If all is good, put a little lube on the stems and see how they feel. If they're good put it back together and see how it runs.

Keep in mind, I'm talking without seeing what you've got. If Dale suggests something different, go with what she suggests.

[Jim Becker]

If cylinder 2 was rusted, chances are the #2 exhaust valve was open while it was sitting out. You definitely need to check the #2 exhaust valve seat for any rust or pitting. (The others should be looked at, but this is a likely start and end point.) If there is any damage to the seats or the sealing surfaces of the valves, you need to do a proper valve job. If a seat is too bad to clean up, it may need to be replaced (machine shop job).

[NJ Farmer]

I would run it a little bit to work the rings and valves past their previous stuck position….el al lapping the rusted areas. Then I would change that motor oil because you have all kinds of crappy debris floating around the oil system that the filter will most likely never catch.

From then on monitor then engine and run it often and hard! Cub motors like to be used….

NJ Farmer