I started stripping one of my recently acquired engines (thanks Smelly) and I found one of this pistons is stuck in the bore.

I have flooded it with oil from both sides and tried giving it a tap but it wouldn't budge. So what should I try next? Or is the treatment usually just give it a less gentle "tap" until it comes out? Or should I just dump it in the caustic soda bath and let that eat away the aluminum in the piston

It will be getting a re-bore so I guess I am not to concerned if it leaves a little score or mark.

Cheers,
Alex

Usually its because its been left standing and the rings have rusted to to the bore wall. It could have been overheated as well and seized but not commonly.

Take the oil out - it wont penetrate enough. Use diesel instead - fill the bore with it and walk away for a week. Then clean out the diesel and spray around the rim of the piston with a proprietary substance called "Yield" (supercrap, repco etc) and give it another day.

Then with a suitable block of wood on top of the piston, give it a few whacks with a FBH. It will shift even if it breaks the rings in the process.

Mike

Further to what Mike said , leave it soak with diesel sitting upright for a week , then turn it upside down and repeat the process . Often when the rings are rusted onto the bore they stop the diesel soaking through so you only loosen the top ring .

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I would fill the cylinder with vinegar.
It works very well.

A few drops of fresh lemon and some fish and chips, to eat while you wait ! Don't forget to remove the crank shaft first so the piston and rod can travel when you hit it with the FBH and lump of wood. Tap it one way and then the other and clean the Bore walls from and rust or corrosion so it can move freely. A cylinder hone works well. Good luck.

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

I havn't heard of that - does work does it.

How does it go on frozen studs and the like ???

My wife wife asked red or white wine vinegar as well ???


Mike

Or apple cider vinegar or rice wine vinegar?

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Mike, find an old rusty iron thing from in the dirt on the farm. Stick it in a plastic tub half full of vinegar. Leave it overnight. Hose it off and treat with oil to stop it flash rusting. you will be amazed.

I have used vinegar on rusted nuts, seized wheel cylinders, clutch slaves, rusty metal, etc.

It does not seem to matter what type of vinegar but I would use the cheapest one.

Ferrous Acetate - highly soluble in water forming a pale green solution. Produced commercialy by dissolving scrap iron in acetic acid (vinegar)

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

brown vinigar is best

sometimes i know stuff

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

I have tried vinegar and acid before on steel parts.
I found that it would eat the rust first but once that disappeared it would start on the fresh steel and eat it away.

So think the moral of the story is check it regularly if you do use acid to clean your parts.

Then a good spray of INOX & a """B F H""" & a block of wood

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.