What causes a leak out the back of the X-valve?

[Loneassassin]

Lately my Mag has been leaking out the velocity adjustment hole on my X-valve. It sometimes goes away if I can get the gun cycling, but then it comes back usually. It used to leak a little upon airing it up, then it would seal up and work great all day. This has come about recently as I've done my final tuning on my pneumag parts. I don't believe those are related to the problem - it seems like more of a ULT or lvl 10 problem. I just want to why the air comes out the back of the x-valve.

I'll probably take the whole lvl 10 bolt apart and lube everything, as well as the ULT. I've been using lots of oil in the ASA every 2000 shots or so, but sometimes I think it's better to apply lube directly to all the moving o-rings...

[Ando]

Is it coming out of the very back where you adj the velocity? There's an Oring on the brass piston that is probably going bad. If it's been replaced then you probably have a piston going bad.

[athomas]

Yeah, just clean the back section out and replace the oring on the regulator piston assembly and you should be good to go.

[Loneassassin]

Do you guys mean in the X-valve itself? Cause this thing is not that old...

The previous owner only put about a half a case through it, and the owner before that apparently didn't use it even once. I've only played with it a few times. I'll take everything apart and inspect all the o-rings.

One other question - is Extreme Rage lube okay to use? I'm down to the last few drops in my Gold Cup bottle, and a local store has Extreme Rage for $3.00/bottle. I tried to find air-tool oil at the hardware store but all of it had petrolium distillates.

[Newt]

Your mag runs on oil. Use the best stuff you can get your hands on.

[athomas]

If a piece of dirt gets on the oring, it can cause leaking.

Use a very light synthetic oil. The orings only have to be moist to reduce friction.

[kit352]

can the oring be repalced with just a nitrile or buna one or do you need a urethane one like stock? my valve started doing the same thing today is the reason i ask. ive got tons of regular orings but no urethane ones that fit.

[athomas]

A nitrile or buna oring will work, but because it is a moving piston, the oring will wear out faster, thats all. That is why a urethane one is used in the first place.

[kit352]

makes sense. i never really thought about it moving. i figured it was just stationary.

[athomas]

The regulator valve pin opening and closing is what determines when air flows in the mag regulator. The pin pushes against the regulator piston assembly. When the valve is empty the spring pack in the back of the mag pushes the piston forward because there is no pressure holding it back. The regulator piston in the forward position holds the valve pin in the open position allowing air to flow. As the chamber fills the pressure gets higher. The higher pressure pushes against the front of the regulator piston and forces it back. When the force of the air on the front of the piston is greater than the force of the spring on the back of the piston, the piston is forced towards the back and allows the valve pin to shut the regulator air flow off. This happens for each cycle of the valve, so the regulator piston moves quite a bit in its lifetime, which is why it requires a good quality oring. This is also why it is critical to keep the area clean. Dirt changes the friction parameters and alters the ability to regulate to a consistent pressure value each cycle.

[Loneassassin]

Well, I think I discovered the source of my problems - the tank I've been using reads 600psi when it's empty, so I've been working with a lot less pressure than I thought. When I attempt to air the gun up when the gauge says "1000 psi", I don't think it's enough to seat everything in the valve.

But it was also leaking out the barrel, then would get better after firing a few times, then start up again. I changed my level 10 carrier to the next smaller one and that problem is gone. I think I was using the biggest one before, and the o-ring has finally broken in enough that the larger carrier is now too large. Plus the bolt is now even softer on the level 10 effect...