X-Valve Issue (single shot mag)

[robertreed711]

So I'm having an issue with a new (to me) x-valve. When I air it up it fires once and then I can hear a small leak and the trigger pull seems to increase and it won't fire again. The first time this happened I de-gassed it and aired it back up, at this point it wouldn't fire and had the heavy trigger pull again. I degassed again but this time I pulled the trigger to reset the on/off pin just as you would to remove the valve, aired it back up and same as the first time, fires once, trigger pull increase, won't fire. I was able to repeat it this way multiple times

I thought it might be the bolt not quite resetting but I pushed back on it and it was seated so that wasn't the issue.

I then swapped valves with another gun and the problem valve had the same issue in another gun but the original gun had no problem with the other valve so I have narrowed it down to the valve and not the gun.

I thought about switching on/off's but I was getting low on air and figured it would be a waste of time. I suspect this has something to do with the on/off or the o-rings above it but I've never had this problem before so it's just a guess.

Any ideas?

[vintage]

what pressure are you running?

[robertreed711]

standard high pressure, 850-900 psi. Functions fine with 2 other x-valves.

[dboggs79]

Sounds like a valve reg issue to me. Pull the reg piston out and inspect.

[robertreed711]

I think the issue was the quad o-ring. I found a different tank with ~1000 psi in it so I took the on/off out of my purple mag which has the 2 urethane o-rings at the top (problem valve on/off had quad o-ring inside urethane o-ring) and tried it in this valve. Everything seemed to function ok so I swapped the o-rings on the original on/off and tried it in the valve and that also seemed fix the problem. Sear reset seemed a little bit slow but I was getting close to having too little air so I believe that was what was all that was causing that.

Let me know if this doesn't make sense.

[athomas]

Replacing the quad oring with a regular oring is the same as putting in a shorter on-off pin. If the sear is rotated too far and the valve isn't opening properly, the on-off pin will push on the sear with more force than if the on-off is fully open. Check the trigger rod length and the length of the on-off pin itself.

[robertreed711]

Replacing the quad oring with a regular oring is the same as putting in a shorter on-off pin. If the sear is rotated too far and the valve isn't opening properly, the on-off pin will push on the sear with more force than if the on-off is fully open. Check the trigger rod length and the length of the on-off pin itself.

Maybe these will answer some questions

[Cyco-Dude]

nice calipers!

[athomas]

A low tank pressure can cause issues. If it is measuring low air pressure on the gauge, then it is possible that the air pressure is actually lower than that. Using a known good tank will probably help.

The gap behind the trigger is good.

Going from a quad oring to a regular oring gains you some distance off your on-off pin. It shouldn't make a big difference in the average valve unless there is a tolerance issue somewhere. The main areas of concern are the rail, body, valve, and sear. The sear is pretty much always correct unless it is worn out. But then it would create an open condition not a closed one. If using an aftermarket rail, it could be an issue causing the sear to sit too high, creating a shorter distance to the on-off. Same with the body. The valve is usually bang on, so it shouldn't be an issue.

Make sure you press the sear pin all the way into the rail if using a classic style rail. Make sure your rail bushing is in place.

If you get it working with a full tank, try the quad oring again. If it causes an issue, you should use a shorter on-off pin. Yes, you can use the regular oring, but it means your pin is too long anyway, so go to a shorter one. You can simulate a shorter pin by adding a level 10 shim in between the two halves of your on-off assembly.

[BigEvil]

So I'm having an issue with a new (to me) x-valve. When I air it up it fires once and then I can hear a small leak and the trigger pull seems to increase and it won't fire again. The first time this happened I de-gassed it and aired it back up, at this point it wouldn't fire and had the heavy trigger pull again.

Sounds like the reg is not doing its job. Replace the reg seat oring and the reg pin orings. Again, like was mentioned, try it with a known good tank.