53 plymouth engines?

[JerseyHarold]

Thanx James the valves all move up and down now, the lifter spin freely, so, I can rule that out, gonna pull timing chain cover and remove chain, that will tell me some more.....

It has been mentioned and disputed here before, but some folks have had good luck unseizing an engine by vibrating the crankshaft nut with an impact gun. Basically a few BRRP's each day over a week or so, not one big impact festival. Keep the cylinders wet with your choice of penetratng fluids.

[Rusty O'Toole]

Do any of the pistons move? Have you tried tapping them down? Make a wooden drift as big as the piston and you will not damage anything.

Usually only 1 or 2 pistons get stuck. 1 or 2 intake valves will be open when the engine is sitting, those cylinders will get rusty and stuck.

Another way to shift a stuck piston. Put the head on, fill the cylinder with oil, attach a hydraulic pump to the spark plug hole. Have even heard of doing this with a grease gun. In that case the mechanic made a plate to bolt on top of the cylinder and screwed a grease nipple into it.

If you can get the pistons to move a little bit it should be possible to get them out. You could try removing the pan and taking out the pistons that will move first, then work on the others.

[Rusty O'Toole]

Another way to turn an engine is to remove the starter and pry on the flywheel with a pry bar. This gives a lot of leverage. Be careful and don't break any teeth off.

[55 Fargo]

I pulled the timing cover, then removed the timing chain, the valves and camshaft are moving nicely, but the crank will not budge.

I might as well fill each cylinder with some type of penetrating goop, and let sit, if that does not work, will pull rod caps and remove pistons, this is getting fun.

Here is a short video showing you what I have done, please excuse my video.

[wayfarer]

That 251 looks pretty clean inside!

If you have rust showing in the holes you might try something like vinegar, some folks swear by Coke (as in Cola), or even something a bit stronger like 'driveway rust remover'.

The large block of wood and a bfh trick is good if the crank is out but not as effective with 5 other pistons holding the crank in place.

[JerseyHarold]

You may want to use a thin piece of plastic (like a strip of milk jug) to clean any loose crud between the pistons and cylinder walls, so the liquid can get to the rings easier.

[55 Fargo]

You may want to use a thin piece of plastic (like a strip of milk jug) to clean any loose crud between the pistons and cylinder walls, so the liquid can get to the rings easier.

okay will try your method, will use the shop vac, and get as much crud, out, then will pour what?

What may be the best stuff to put in the cyls to try and loosen up the suspect psiton.

Should I use a wooden dowel(does it have to be round, or just fit in cyl), and gently tap each piston to loosen things up.

I am hoping to rebuild this engine, with whatever machine work done bya shop, and I will do assembly.

My current engine is running well, so I am in no rush, this can be a couple year thing.

[Young Ed]

Fred I'd use ATF. And a dowel is probably too small. You want something like a 4x4 or something as big as the cylinder.

[55 Fargo]

Fred I'd use ATF. And a dowel is probably too small. You want something like a 4x4 or something as big as the cylinder.

Thanx Ed, will fill em up with ATF tomorrow, should I add any solvent to that mix?

I was thinking of having my Dad make me a round dowel, almost as large as the cylinder, he could turn this on a wood lathe, and make it out of oak.

Or I have some real heavy 3 X 3 asian hardwood pieces, that I could try

[Rusty O'Toole]

Rockwood I would try oiling with ATF or Marvel Mystery Oil and prying on the flywheel with a pry bar in the starter opening. If that did not turn the engine the next step would be to take off the pan, carefully remove the rod caps, and take out the crankshaft. Then remove the pistons one by one.

Do not mix up the rod caps and put them back on as soon as the crank is out of the block. When the caps are off cover the bolts with pieces of rubber hose to avoid scratching the crankshaft.

First tapping them down with a piece of wood then when they are free, push them up and out of the cylinder. If there is a ridge around the top of the cylinder you have to remove it with a ridge reamer or the rings will hang up. The pistons will not come out the bottom of the engine.

The piece of wood needs to be a 2X4 or stove wood carved to fit into the cylinder and cut off flat at both ends. Rest it on the piston and strike with a big hammer. A carpenter's hammer is not big enough you need a ball pein or sledge at least 1 pound.

If you can get a wooden plug made the exact size of the cylinder it would be perfect. It does not have to be hardwood or any special wood.

[55 Fargo]

Rockwood I would try oiling with ATF or Marvel Mystery Oil and prying on the flywheel with a pry bar in the starter opening. If that did not turn the engine the next step would be to take off the pan' date=' carefully remove the rod caps, and take out the crankshaft. Then remove the pistons one by one.

Do not mix up the rod caps and put them back on as soon as the crank is out of the block. When the caps are off cover the bolts with pieces of rubber hose to avoid scratching the crankshaft.

First tapping them down with a piece of wood then when they are free, push them up and out of the cylinder. If there is a ridge around the top of the cylinder you have to remove it with a ridge reamer or the rings will hang up. The pistons will not come out the bottom of the engine.

The piece of wood needs to be a 2X4 or stove wood carved to fit into the cylinder and cut off flat at both ends. Rest it on the piston and strike with a big hammer. A carpenter's hammer is not big enough you need a ball pein or sledge at least 1 pound.

If you can get a wooden plug made the exact size of the cylinder it would be perfect. It does not have to be hardwood or any special wood.[/quote']

Thanx Rusty, will soak in ATF or Marvel, how long should I leave it?

I have lots of wood around here to make my weapon, and several hammers to pound some sense into the pistons.

I would like to see if I can free up the pistons, without removing them at this point.

I have no ridge on the tops of these cyls, well maybe a couple allows my finger nail to slightly snag, and I mean slightly....

[RobertKB]

Hey Fred, I am following this with interest. Keep us updated! Might be an idea to start a new thread as this one has covered a lot of other ground as well.

[55 Fargo]

Hey Fred, I am following this with interest. Keep us updated! Might be an idea to start a new thread as this one has covered a lot of other ground as well.

Me too, I am all fired up about this, could possibly start a new thread.

I am hoping to work on this engine a bit mor tomorrow....

[Broke4speed]

I love discussions like this. I had never thought about using the hydraulic pressure method of unseizing an engine. I've had good luck in the past with ATF and a chunk of wood, on old VW Rabbit engines...but I think the steady pressure method would be wicked to try.

I know of a DeSoto 291 Hemi that's frozen tight...cheap too...

[Rusty O'Toole]

I would push the piston down, clean the cylinder with fine sandpaper, oil it and push the piston out. If the rings snag on the ridge you will have to remove it but if it is as small as you say it should be no problem.

If you can get the pistons bead blasted it will clean them up and make it easier to get the rings out. If they are stuck in the piston some heat should help free them up, the main thing is to not damage the ring groove, it is OK to break the rings as they are to be replaced anyway.

In the worst case new pistons are $65 a set for NOS, $155 for brand new from Vintage Power Wagons.