Hydraulic cylinder piston ring removal?

TimWafer · Jul 27, 2019

I'm rebuilding the power steering cylinder on my Gleaner K2. It was leaking like a sieve. The rod was badly pitted and I'm making a new one out of a rod blank. Ive got all the seals for that but was wanting to replace the piston ring as long as I'm doing it all. It looks like a solid aluminum piston with a single groove in the middle. (its a two way cylinder). The parts book lists a Teflon piston ring and an oring. Maybe the oring is under the Teflon ring? Anyway I cant figure how to get that Teflon ring off or a new one on. Its hard and appears brittle and I see no gaps at all in it and it fits tight in the groove. See no way it could possibly stretch to fit. I see no seams in it or the piston. How was it even installed initially.
I can probably leave it alone and use it as is but it does have a little wear on it and if possible I would replace it.
Anyone familiar with this type of ring?

Bob · Jul 27, 2019

Automatic transmissions commonly use rings like that. Heat the new one up in hot water, carefully stretch it into place, then "work" it down into the groove.

For some applications, there's a "re-forming tool" much like an internally-tapered piston ring compressor that you work over the ring to squash it down into the groove, then leave it in place for a bit to "encourage" the ring to assume it's original (smaller) profile.

MARK ROBKE · Jul 27, 2019

You can cut or pry the Teflon seal off-it does ruin it. The o ring will be under it. To install the new one, I lube everything it comes in contact with, with white lube. I heat the Teflon seal in a Styrofoam cup in water in the microwave-almost boiling. however you chose to do it, but keep the seal in the hot water until you immediately install it on the piston. Try not to distort it as you work it into its groove. Allow it to cool, and use a small piston ring compressor to squeeze the ring back to size in its groove. I let it sit with the ring compressor on for a while before I put the piston in the bore, lubing the bore with white lube also. Mark.

Eagle Beagle · Jul 27, 2019

You can also cut a pop can into a strip wider than the seal. Wrap the strip around the seal and place a worm gear hose clamp tightened up to help shrink the seal. The clamp will damage the seal without the strip.

Beagle

teddy52food · Jul 27, 2019

A few wraps of electrical tape to hold it down in the groove, then put it in the freezer for a while will
keep it in the groove. Hot water to soften it to stretch it on.

TimWafer · Jul 27, 2019

Thanks Guys!

Cliff Nelson · Jul 27, 2019

I use this procedure regularly but cut a strip from a plastic jug instead if aluminum.

Hydraulic cylinder piston ring removal?

TimWafer

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Bob

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MARK ROBKE

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Eagle Beagle

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teddy52food

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TimWafer

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Cliff Nelson

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