SouthBend A Stuck Piston

[T….in Wisconsin]

Looking for advice on freeing up a stuck piston.

It has been advised to soak in Acetone & ATF.

Appreciate any feedback on what has worked for others.

Thanks

[joecb]

Your best “tool” is to use a lot of patience.  Go slow, soak with penetrant of your choice, repeated heating cycles will help too. Can you tap (hammer!)  on a hardwood dowel down thru the spark plug hole? Do not try pulling hard on the connecting rod, likely break the rod. Since the piston skirt is exposed, try supporting the skirt on wood (wood board with hole to clear the rod end) and pressing on the cylinder to gain some movement, if it moves , then work it back and forth. Using the “grease – gun ” pressure system will require blanking off the ports which may be a problem considering how far down the piston sits. If you end up “pulling” don’t pull on the rod, try to get a hold on the wrist pin , wrap wire etc and pull from that. I like the “start” pushing in approach , get some movement going. … Patience and soak.

Joe B

[T….in Wisconsin]

I’ll continue to soak along with heat cycles.

Why tap thru the spark plug hole with a dowel? piston has cleared the hole.

Thanks, I appreciate your advice.

 

[Tubs]

Tubs.

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

[T….in Wisconsin]

Ingenious set-up!

Did you use heat to help break it free?

Thanks

[joecb]

It appears that we have a failure to communicate. You wrote…

“Why tap thru the spark plug hole with a dowel? piston has cleared the hole.”

the piston appears to have cleared the exhaust port, sure,   but the spark plug hole is at the top of the cylinder?  unless of course the spark plug hole is at right angles to the bore in which case your comment makes sense.

Just another word of caution about pulling from the conn rod, do not use extreme force as you may break the rod, especially if its bronze.

Joe B

[T….in Wisconsin]

Good morning Joe,

Yes, the spark plug hole is 90 deg to the bore.

I understand the concern as to not break the rod ends.

I’ll make sure the piston has broke free of the bore before trying jackscrews to remove, and then with caution.

Thanks for the advice.

[T….in Wisconsin]

Pic for reference

[Tubs]

After letting the cylinder soak my first attempt was to applying 120 lbs of air.
Second attempt was to fill the cylinder full of paper towels soaked with trans
fluid, blocking the exhaust port, and trying to push it out with grease. Most
likely I had applied heat at some point but I don’t have a clear recollection of
doing that. This motor came from a metal shed with a dirt floor where it had
sat for decades. When the cylinder moved for the first time it sounded like
the crack of an aluminum baseball bat. When tightening the nuts the cylinder
would jump a bit when there was enough pressure. It took several hours to
separate them. The brass rod survived without issue. I expect that once you
get the piston to move it won’t be to difficult to remove, but again don’t try
twisting the piston using the rod.
If this wouldn’t get it out I was going to have to get replacement parts.
If I broke the rod I was going to have to get replacement parts.
If yours is in the same condition as my example, the cylinder it likely
unusable. My piston wasn’t salvageable either. I did reuse the rod.
In any case use, your best judgment.
Tubs

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

[joecb]

Tubs, Good info.  Looks like you would have had to block off the intake passage too once the piston moved down a little way.

And another caution for Tim, from his photo, looks like the cylinder is from an opposed twin, hence the off-set conn rod. This will present an issue if attempting to pull on the rod, as it not a straight pull like on Tubs cylinder. Even more likely to damage the rod.

Joe B

2 users thanked author for this post.

T....in Wisconsin, Tubs

[Author]

Posts