Possible seized engine?

I have a 55 AC CA that I have broken the engine down. The pistons look pretty good but I can't get it to crank over. I placed marvel mystery oil onto the piston about a wek ago. With it out of gear or the clutch pushed I can not move the crankshaft at all. The was only a list rust on 4 of the valves. I have the starter off. It hasn't been turned over for at least 10 year but under a shed. Any thoughts?

You could pull the pan to see where the crank is and if it is horizontal you could take a block of wood and persuade the pistons to go down (starting at one end and working back and forth). That should get it free. You could also put your favorite rust penetrator in there and then put it in high gear and rock it. Or pull the pan and unbolt the rods and pound on the pistons until they give and then push them out the top so you can rehone the sleeves.

I would probably try it in the rock in gear method first, then blocks of wood and finally pull pistons. Since it has been shedded it hopefully won't be too bad.

if you have the head off, pour a bit of fuel oil in the cylinders, and light the fuel and let it burn so the block gets warm, or just evenly heat the block with a propane torch. Also, make sure the trans is in N, and the clutch is not stuck on the transmission shaft, and stuck to the flywheel.

Maybe that crankshaft has tied itself into a half-hitch knot. :>)

Allan

Unbolt the connecting rods one at a time and try to drive out the piston with the sleeve using a piece of 2 X 2 oak and a big hammer. Pour ATF on the pistons and let them soak. Hal

I tried everything on a "b" i rebuilt once,brake fluid,atf,mystery oil,deisel,a dozen different penetrants.the one thing that finaly worked after a couple months of struggle was a product called "break free" i bought at a plumbing supply house.i sparayed it down and the next morning i was able to turn engine slightly by hand.once it started moving i simply moved it back and forth until i worked it over tdc on that cyl.then i cleaned it up good and sprayed it again and let it set overnight .i had pounded until i gave out on the top of that piston and it never budged till then. i pulled that one piston,unstuck the rings.reinstalled it set the shims in rod bearings right and fellow is still using it,that was maybe 10-11 years ago.about the only tractor i ever made in any money on i think when i sold it.a got it for hauling it off, and had the price of a gasket set in it when a fellow stopped and wanted to buy it.i told him what the deal was,that i had had just threw it together to pull a trailer.but he offered me more than i could refuse.and in fact called a few weeks back wanting to buy another one just like it!those ac's are tough old tractors.i picked up a bunch of scrap ones( and i do mean scrap from a tractor wrecking yard) and in the piles were the remains of three or four.i cobbled one up out of those that had the front steering from a wc,the engine from a wd45 that had a crack and a patch all the way down the side of the block lenghthwise,and the trans and rearend from a wd.old buddy of mine needed a tractor for mowing so i gave it to him, has ran it for probably 15 years every summer and fall mowing his pastures.guys must have got on to how easy they are to fix because you sure dont see them setting around like you used to around here anymore.

Use some rags to soak up that MMO and then fill with ATF. Le ti sit a few days and then if you can do so safely put a tablespoon of gas into the ATF and light it up. Keep adding gas to to the ATF and relighting till 90% has burned off. ALWAYS wait till the fire has gone all the way out before adding more gas. If it does not free up that way you will have to pull the oil pan and take the rods loose and pop the sleeves out. Yep BTDT on a C

With starter OFF, can you use a big bar to lever ? Don't knock the teeth off. What about wrench on front pulley. T bar so you give equal pull and don't snap the bolt off. Dave