Stuck piston ring

I've got a slightly strange issue with the top ring on my Villiers MK20 piston. All the other rings are perfectly free, but that one is stuck in it's groove. It's slightly proud of the piston around most of it's circumference and can be pushed back into the groove against the 'springyness' of the ring, but it is flush at the point of the gap and jammed in the groove. It's as if the groove has closed up and 'nipped' the ring at that point. I'm wondering if putting it in the freezer might shrink the piston enough to free it?

It wiil shrink as will the piston and you will gain nothing. you would be better gently filing the groove where its tight.

Maryalice

Be better to boil it in diesel or coke.

maryalice wrote:It wiil shrink as will the piston and you will gain nothing. you would be better gently filing the groove where its tight.

Maryalice

I will when I can get the ring out...

Propane, Plus Gas and Patience.

mattblack wrote:

maryalice wrote:It wiil shrink as will the piston and you will gain nothing. you would be better gently filing the groove where its tight.

Maryalice

I will when I can get the ring out...

You may already  have a lip holding the ring in place hence my suggestion you carefully file the groove to remove any edge,

Maryalice

maryalice wrote:

mattblack wrote:

maryalice wrote:It wiil shrink as will the piston and you will gain nothing. you would be better gently filing the groove where its tight.

Maryalice

I will when I can get the ring out...

You may already  have a lip holding the ring in place hence my suggestion you carefully file the groove to remove any edge,

Maryalice

Hmm, I can see where you're coming from but it's very tight, I've stuck it in the freezer anyway as my thoughts are if the piston shrinks the groove will effectively get bigger...

[quote="mattblack"]

Hmm, I can see where you're coming from but it's very tight, I've stuck it in the freezer anyway as my thoughts are if the piston shrinks the groove will effectively get bigger... [/quote]

Good thinking batman, and by that logic the ring will get smaller too.....

Alluminium expands 2.4 times that of steel so Its fair to assume that alluminium shrinks at a similar rate so putting it in the freezer will cause the gaps to close and trap the rings even more.

Maryalice

I've got it sorted now. The freezer thing didn't work so I carefully ran a craft knife around the top and bottom of the ring where it was tight then applied some WD-40 and used the piston ring compressor to push the ring back in the grove. Then I gently 'worked' the gap with a small screwdriver and repeated the compressor thing until one end of the ring came free. The other end needed some gentle persuasion with a small punch before it came out of the groove. It looks like it was just a build up of carbon that was holding it, it's all cleaned up and back in now.

Well done. I usually end up breaking them!