Hello everybody,
Do you guys have tips on how to remove a piston ring that is completely stuck into its slot?
I have tried:
- WD40
- softly hammering with a rubber mallet
- heat (flame)
- infrasound
But nothing worked, I can't even get one end sticking out to apply a lever.
I don't mind damaging the ring as I'm going to change all of them, and it looks to be broken in two anyway, but I want to preserve the piston.
Thanks!

I think I would be leaving the piston in a saucepan on the hob in boiling water
As aluminium and steel expand at different rates

Old pan full of diesel, warm is better and leave it immersed a few days.

Think i'd try alternating between pan of bowling water for about 20 mins ... and then a trip to the freezer for a few hours ..... followed by a soak in some wd 40 type liquid.

Good luck !!

Why is the ring stuck? If it is due to carbon build up it might be possible to soak the piston in something that will soften the carbon. Gasket stripper will soften carbon but might effect the piston if left too long. If the ring is stuck due to mechanical damage then it’s likely to be scrap

Hi,
The ring was stuck because of carbon build up and/or engine having been too long without running (old 1984 Kawa ZX550). Definitely not mechanical damage.
Anyway, thank you very much for your answers guys.
After a series of alternating boiling water/cooling in cold water, I could manage to have one end of the ring sticking out enough to use a tiny screw drive as a lever, and I could removed the ring. Finally!
Thank you very much for the tips guys.
A nice week-end to everyone

If you can find anyone with a proper degreasing tank that will do the job. I had some stuff called Turco Transpo that my engineer recommended when I was rebuilding the Auster engine. Bloody expensive but shifts anything. Drop something in overnight, tickle with a paint brush then wash in water - comes out as new. Great for stuck rings and exhaust valves. I've still got a small tub left but I'm too far away to be of use to you