I was given a leaky old Crosman Mark 1 by a friend and told, 'if you can fix it, you can have it'! I am rebuilding it at the moment, but am having some unusual problems with the o-rings. I found the correct size from the tbaytel website and bought them in Viton. When I assembled the pistol it didn't leak and would fire ok. I didn't shoot any pellets, just fired it without the bolt in place. The next day, nothing! I figured it had leaked overnight so I tried to unscrew the cap on the base of the handle. It was really tight and I had to resort to pipe grips to undo it, but when the o-ring on the cap was exposed, it started to fizz and pop! I pulled it out and watched it writhe around and bubble up on my workbench! What's going on? Is Viton not compatible with CO2? The o-ring on the valve body was also bubbling when I took it out. I have ordered the correct size o-rings in urethane, so I will see what happens.
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Crosman Mark 1 o-ring problem
- Thread starter shooter64
- Start date
I've had the same effect with some hydraulic shop seals, not with others. Huge, distorted seals, then normal looking after sitting overnight.
Urethane should be the fix. Or a different composition seal than the one you had, anyways.
Cheers
Trev
Urethane should be the fix. Or a different composition seal than the one you had, anyways.
Cheers
Trev
Nope, Viton is not compatible with CO2. The CO2 molecules are able to penetrate the Viton, and you saw the result. Even though the o-rings will eventually return to "normal", they will be filled with tiny pinholes, as a result of the little bubbles of CO2 bursting.Is Viton not compatible with CO2?
The best o-rings to use are 90 durometer urethane.
Running a close second are 90 durometer Buna-N.
