Stuck Piston

[41craig]

I have a 1924 J motor with a stuck rear piston. I removed the front cylinder with no problems. This is a side project that I'm in no hurry to rebuild. I removed the spark plug several years ago and spray Kroil, PB Blaster, or whatever I have in my hand, into the chamber every so many months. It has cast iron pistons. Any ideas ? Or should I keep doing what I have been doing ?
Craig

[JoJo357]

Try using any cheap ATF Craig. Soak for 3-4 days, try working it in-between, repeat if stubborn. Always worked for me.

*M.A.D.*

[TechNoir]

I am no expert but I would certainly try more penetrating fluid and maybe heat. Not oxy torch but heating the cylinder up to, say, 100 degrees C which is about 212 Fahrenheit


If that doesnt free it off then I would strip the motor. Assuming that the piston is not stuck at TDC then you should be able to split the cases which would leave you with access to the piston from underneath albeit with a rod and crankshaft attached. More penetrating fluid can be applied from underneath. And then heat again.

If that still doesnt work then you could try acid which should remove the rust and might free it up.

If that doesnt work then its mechanical means which would be to cut the piston out but that would be a long way off and the last resort after trying the previous steps.

Just my thoughts though as I have never tried this.

I am sure others will have suggestions

John

[exeric]

I've had to do this 4 times. Twice with blind bore cylinders, and twice with Honda cylinders. In every case, I made a wooden buck that would just fit in the cylinder and catch the bottom, or top of the piston. For a Honda piston, the buck needed to be relieved for the piston dome so your force was concentrated on the outer diameter of the piston. Pre-lubrication for weeks, months, or years can only help As soon as the piston moves, you're on you way to success. My only failure was with an Excelsior piston that was near the top of it's stroke in the cylinder. I did have access through the top motor mount stud hole but I just put a hole in the top of the piston. Cast iron pistons are great for old bikes but they can really lock up after decades of neglect. If I had to do it again, I would make a slide hammer puller that would put the force on the wrist pin. Good Luck !

[cHarley32]

I have always mixed acetone with the ATF fluid with good results. 50-50 mix.

[T. Cotten]

... maybe heat. Not oxy torch but heating the cylinder up to, say, 100 degrees C which is about 212 Fahrenheit..
John

"Brooder lamps" are safe and effective, Craig!

("Heat lamps" to city Folk.)

If not effective, there is little to save from the chisel anyway.

....Cotten

[41craig]

Many thanks to all that replied ! You have all given me a boat load of advice. One question about using acid. Won't that cause more rust ?
Craig

[T. Cotten]

Many thanks to all that replied ! You have all given me a boat load of advice. One question about using acid. Won't that cause more rust ?
Craig

White vinegar is acid, Craig!

I go through gallons. (Or used to...)

The question becomes how to apply it.

You want it to soak somehow. And 'brooders' can still help.

....Cotten

[41craig]

Thanks Tom !

P.S. That lamp looks like it came from Frankenstein's lab !
Craig

[T. Cotten]

Thanks Tom !

P.S. That lamp looks like it came from Frankenstein's lab !
Craig

Yes, Craig!

The bulb's socket threads came loose, so it was wired up direct, goobered with silicone, and suspended with Fisher lattice clamps. The stand itself is as I found it, and I have no idea of its original purpose.

That was perhaps three decades ago, and has endured almost daily use until quite recently.

One would think vibration would have gotten to the element by now,... but,.. it's ALIVE!

....Cotten

[gharper]

Craig,

I recently managed to save a set of Excelsior cylinders in the same condition. Soak, for a long time!!! I started with diesel fuel. I also like marvel mystery oil as a penetrant. Maybe the best mix is the 50/50 acetone and ATF, the Acetone really creeps in.

Next, disassemble the cylinder and crank. Hopefully all you have is one cylinder with a piston and rod stuck in it. Make a solid base to mount the cylinder on so you don't damage it. steel or aluminum is best but even good 3/4" plywood will work. Bore a hole for the base to rest on with the locating flange in the hole. Bolt all 4 ears down solid. Now you can work on the cylinder without fear of damage to the base. Remove the plug at the top center and the intake valve cage. Soak some more! Bead blast the bottom of the cylinder to make as clean a path as possible for the piston to come out. Soak some more. Put the largest piece of steel you can slide in through the intake cage pocket and onto the top of the piston. Use a steel rod to go through the top center hole to push or drive. Rest the end on the steel plate and drive the piston out if possible, or use a press, carefully! Of course, support the base as much as possible all the way around to avoid damage. Soak some more.... Use some heat..... Tap, tap, tap, heat, soak, and continue. It may budge, or come all the way out, or not move at all.

I was able to get one out this way, the second was so bad I had to remove the steel disc, bust out the top of the piston and pound on the top of the rod (wrist pin actually, as my pistons were not attached to the rods) Finally had to make careful relief cuts with a hack saw and then break them out.

Once removed, the bores were in decent condition, except where water got into the top and sat for decades! Huge pits all around. Those cylinders are getting a NikaSil lining as we speak.

Good Luck! Patience and perseverance pay off...

[T. Cotten]

... It may budge, or come all the way out, or not move at all... .. bust out the top of the piston ...Good Luck! Patience and perseverance pay off...

You're scaring Folks, Gene!

I only had to do it a coupla times.

My pertinent note is that after such abuse, the rods MUST be scrupulously inspected for "straight", and re-aligned, after a full refurbishment.

As any and all should be anyway. But more so. "Patience and perseverance pay off" with a lot of 'observation' along the way.

...Cotten

[Highlander]

Gene, not to get off topic though, I am curious as to who you are getting to apply the Nikasil linings for your cylinders? Thanks.

[41craig]

Well, I just pulled the motor out from under all the debris ( My shop is a wreck right now ) and the piston IS at top dead center. I tried to remove the intake housing to get a better look, but the cap nut is stuck. So now I'm soaking it. This may be why I shelved it years ago. Meantime I'll finish my '50 EL and then start to put my '42 EL motor back together. It's a good thing that I retired 3 years ago so that I can relax.
Craig

[Arley]

the antique tractor people plumb a hydraulic hose to the spark plug hole. Hook the hose to a tractor's hydraulic outlet. The piston will move ,I am sure it will be messy.