Evinrude RBM piston rings

[Bill Roth]

I had a stuck piston on a 1914 Evinrude and using the wax method we finally got it out. While cleaning the piston I may have stretched the lower ring to much loosening it up. These rings are pinned to the piston. Has anyone found a safe way to get it back close to specs? I was thinking of clamping it and applying heat, but will it go back to closing the gap or create a bigger gap?

Any ideas would greatly be appreciate!

Bill in MN at: anbroth1544@gmail.com

• This topic was modified 4 years, 7 months ago by Bill Roth.

[Tom]

What makes you think it’s stretched? Unless it’s been heated a lot, stretching it without breaking it is unlikely.

T

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Bill Roth

[RICHARD A. WHITE]

With no disrespect to you, the rings are intentionally bigger than the bore when relaxed. That is so that they “ride” on the cylinder walls to give the compression needed to keep the engine running.

My experience is that if I work the ring too much trying to remove it…they break…. makes me say bad words, but then it is always my fault they break.

Put the ring in the bore, by itself, use the bottom of the piston skirt to ensure it is true in the bore, measure your end gap to proper specs, if it is the range, reinstall it on the piston an go.

Regards

Richard

http://www.richardsoutboardtools.com
classicomctools@gmail.com

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ROGER HUDSON, Bill Roth

[PM T2]

I would have to say that it’s practically impossible to bend these rings enough to actually spring them out of spec. Trust me when I say that the ring will tell you in its own special way that you’ve over-stressed it in an outward direction because you will turn a single-piece ring into a two-piece that requires an impossible do-it-yourself assembly job to make it useful again.

Put it back in its groove, compress it properly, and reinstall it in t he bore and things will be fine.

Hope this helps.

Best,
PM T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...

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Bill Roth

[Bill Roth]

We found that It wasn’t stretched. Yesterday with a second set of hands we were able to compress it and tap it in. Thanks for your comments!

[Bill Roth]

Got the piston/rings in with a second set of hands and a little tapping. Thanks for you suggestions!

[RICHARD A. WHITE]

Awesome…..

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[Bill Roth]

RICHARD A. WHITE wrote:

With no disrespect to you, the rings are intentionally bigger than the bore when relaxed. That is so that they “ride” on the cylinder walls to give the compression needed to keep the engine running.

My experience is that if I work the ring too much trying to remove it…they break…. makes me say bad words, but then it is always my fault they break.

Put the ring in the bore, by itself, use the bottom of the piston skirt to ensure it is true in the bore, measure your end gap to proper specs, if it is the range, reinstall it on the piston an go.

Regards

Richard

Took your idea and that worked. Thanks

[Bill Roth]

RICHARD A. WHITE wrote:

With no disrespect to you, the rings are intentionally bigger than the bore when relaxed. That is so that they “ride” on the cylinder walls to give the compression needed to keep the engine running.

My experience is that if I work the ring too much trying to remove it…they break…. makes me say bad words, but then it is always my fault they break.

Put the ring in the bore, by itself, use the bottom of the piston skirt to ensure it is true in the bore, measure your end gap to proper specs, if it is the range, reinstall it on the piston an go.

Regards

Richard

Took your idea and that worked. Thanks

PM T2 wrote:

THANKS

[Author]

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