XValve Leak

[3DSteve]

I have an Xvalve with a confounding leak.
It leaks from the middle of the gun. I can hear it from the barrel, feedneck and near the trigger.
It leaks when the trigger isn't pulled. When I pull the trigger, it continues to leak but dies out and stops leaking after 4 or 5 seconds.
I've tried several carriers and carrier Orings.
I've tried new on/off top orings
I installed a ULT.
Swapped out the Reg Valve Pin assy
I tried a different rail/body/sear combo.
I tried a different bolt.
The leak persists despite any of these.
Any ideas?

[Justus]

Diagnose first by cutting the valve in half. You say that the leak dies when you pull and hold the trigger. That pretty much means that the on/off is doing what it's supposed to do, and your leak is located somewhere in the powertube. Leave your on/off alone and just narrow your search to the bolt.

You mention X-valve, so that means a Level 10 bolt. Check first to make sure that you have all the internal parts - the backing washer, carrier o-ring, carrier with the thin black outside o-ring, and the powertube tip with o-ring. Inspect your carrier o-ring to make sure it's free of any damage. Put a drop of oil on it and rub it between your fingers. Then insert it into the carrier with two lines, no dots. Assemble the powertube, no shims, and check for leaks. If it's just a tiny tiny hiss, then oil your valve (put 4 to 6 drops of oil into the fitting closest to the valve; take off your barrel; air up; fire a couple dozen times). If it's a fairly decent leak, then you need to go down a carrier size. Remove the carrier but keep the original carrier o-ring. Put that o-ring into the carrier with one line and one dot. Assemble. Check the leak. If still leaking, go down another carrier size, keeping the original o-ring still. The next one will be one line, no dots. Followed by one dot, no lines. Followed by no dots, no lines. If you get to a point where you don't have any leak, but the gun won't fire consistently, it's likely you're experiencing bolt stick. This is because you've reached a carrier size that puts too much friction on the bolt stem, and doesn't allow the air pressure behind the bolt to overcome the force of the bolt spring. If that happens, go back up a carrier size and run a few hundred shots to break in the o-ring. Then move back down a carrier size to stop the leak.

If all that fails, set that o-ring aside and try again from the top with a new carrier o-ring. If you're using a brand-new carrier o-ring, know that sometimes they have a break-in period as described.

[3DSteve]

Thanks for taking a crack at it, Justus, but I don't believe that is the problem.
I'm sorry. Perhaps my 1st post wasn't very clear, but I've already done that.
This is an exceptional leak. I've tried all the normal things. I have a healthy XValved mag, and two parts kits from which to swap parts on this leaky Xvalve and have yet to find a way to make it stop. Pulling the trigger DOES stop the leak EVENTUALLY, but it takes about 4 seconds of hissing.
I've swapped the entire Regulator, on/off, and power tube assy (including the bolt) one at a time and haven't solved the problem. The closest I came was by swapping the on/off with my ULT from the healthy mag. The gun didn't leak when initially aired up, but firing it made the leak reappear permanently.
It's a factory annodized Red Xvalve. Could there be a problem with some body tolerance? This seems unlikely. Could a previous owner have messed something up in the body? Am I insane?

[Justus]

If the leak stops when you hold the trigger, even if it takes a few seconds to trail off, it means that your on/off is working properly. It's not the back half of the valve, it's got to be in the powertube. (Taking a few seconds for the hiss to stop just means that the leak is small enough that the built-up pressure in the powertube, after cutting off the air supply by holding the trigger, needs that amount of time to vent to the point where you don't hear the leak anymore)

Check to make sure everything is okay with your powertube. No cracks, and no ability to unscrew it from the valve.

[athomas]

I agree with Justus. it definitely sounds like a powertube issue.

You mentioned that you changed carriers and such, but you never mentioned removing the shims. Too many shims will cause your problem. A worn sear will also cause the problem.

Always remove the shims when tuning and testing a level 10 bolt for leaks or force. I wouldn't even put them back in if they were there. Then use the largest carrier that does not produce a leak using the same white powertube oring in each carrier.

[3DSteve]

There are no shims in the lvl 10.

I'll try another sear again.

[Tunaman]

Did you use orings from an RT parts kit?

[3DSteve]

Tuna - Yes

It's definitely an On/Off leak.
I've got it working without leaks with the regular RT on/off now. It just leaks with the ULT.
It's slow going, but I'll dig into it more tomorrow.

[OPBN]

Did you change the O ring on the LVL powertube cap?

http://www.airgundesignsusa.com/downloads/RT-ULE.Tac-One.Manual.pdf

#4 on page 13.

[Tunaman]

Tuna - Yes

It's definitely an On/Off leak.
I've got it working without leaks with the regular RT on/off now. It just leaks with the ULT.
It's slow going, but I'll dig into it more tomorrow.

If you used an RT parts kit. Make sure you didn't put a banjo bolt oring on the on/off. I have done this myself. They are very close in size to the on/off/powertube oring.

[Tunaman]

Did you change the O ring on the LVL powertube cap?

http://www.airgundesignsusa.com/downloads/RT-ULE.Tac-One.Manual.pdf

#4 on page 13.

This oring is static and does nothing but stop the powertube tip from unscrewing by itself. Theoretically you never have to change it unless it breaks.