Help with leak.

[051473]

Just got a used phantom that seems to be in very good shape. I have only fired it a little in my backyard and mostly it works great. But sometimes the gun leaks when I cock it.

If I hold the cocking handle back air continually leaks out the barrel. Then it will not cock. After draining all the air the gun will cock again.

Like I said, this only happens sometimes. Seems to happen after making a velocity adjustment. Any help with this?

PS Got my safety fixed. Thanks guys. Also, is there an average number of clockwise turns to get about 280fps when using a blue main spring assuming a good paint to barrel match? Thanks again.

[thkyle]

Check the valve.....
* Is the valve spring strong enough?
* Is the cup seal connected to the power tube?

"Something" is forcing the valve open when you cock the gun. It should NOT be possible to cock the gun with no air. A Phantom that is working properly will only cock and fire after it is aired up. Being able to cock the gun without air is not a good thing.

* Check to see that the sear is not jamming up and will easily slip onto the bolt. This can be done by removing the valve and hold the handle of a screw drive that will fit against the hammer and try to watch how it cocks. Or take the hammer and blot out and fit them together.

A bound up main spring can cause too much pressure against the valve.

A TPC that has been screwed out of the bolt will cause too much pressure on the valve.

If none of the above work........find a kitten that will lick the gun, and it will work again. 

[Rayodder]

Terry nailed it on the head, if you can pump without air and simply pushing back the pump arm vents gas,that means your springs are too weak to do the job and the input pressure is too low.

By any chance this is an attempt at a low pressure?

[Have Blue]

Are you by chance trying to run with an inline regulator?  If so, remove it from the system - Phantoms crave high pressure.  Is this CO2 or HPA?

[051473]

Thanks terry I will check everything you suggested.

No reg or low pressure. Basic VSC setup.

Just to clarify, I should not be able to cock the gun and "dry fire" it without air?

[B]

Thanks terry I will check everything you suggested.

No reg or low pressure. Basic VSC setup.

Just to clarify, I should not be able to cock the gun and "dry fire" it without air?

Correct make sure you air source is full not enough pressure will the same things.

[thkyle]

Thanks terry I will check everything you suggested.

No reg or low pressure. Basic VSC setup.

Just to clarify, I should not be able to cock the gun and "dry fire" it without air?

Affirmative!    A Phantom needs the air pressure in the valve to hold the cup seal closed and the power tube forward. That force inside the valve needs to be stronger than the force required to compress the main spring and allow your hammer and bolt to come together and the sear catch.

If you can cock the gun without any air pressure in the valve, something is wrong, come loose, etc. with the internals.

Refer to the phaq section to see the order that the hammer, spring TPC, and bolt goes together. You should start with the TPC screwed all the way into the bolt and then turn it out 3 turns. With stock springs, that should be close to 285 fps. Also make sure that the spring goes inside of the sleeve on the hammer, and inside of the bolt around the TPC. If done right, then the total length of the bolt, spring and hammer is not long enough to cock the gun without air pressure in the valve.

Two common causes of what you describe are: 1. The TPC being turned more than 6 turns and coming out of the bolt. 2. The main spring not being seated in the hammer and bolt all the way.

Both will make the length of the internals long enough to cock the gun and also cause damage to the parts.

[051473]

Thanks. I will have time to check this out this weekend. Really appreciate the help.

[051473]

With no air the valve spring holds the power tube forward. As I cock the gun the valve spring should depress allowing the hammer to move back so the bolt cannot attach to it.

With air the air pressure will hold the power tube forward which holds the hammer forward allowing the gun to be cocked. I think I have this right so far.

Everything seems to be fitting together just fine. I believe the solution is either a stronger main spring or a weaker valve spring. Can I cut the valve spring down a little or is this a no-no.

[051473]

Well I think I got it. Pulled out my handy dandy spring kit. Installed the red pill, um...I mean main spring and the stock valve spring. Gun will not cock without co2, the pump stroke is much smoother and no leak.

Thanks again for all the help.