Classic Valve Leaking From Power Tube

[audioSLAVE]

Classic Valve, level 7, .220 spacer, rail bushing in place, HPA, leaking down barrel, pull and hold trigger, leak stops.
Replaced PT o-ring, tried .215 spacer, fed it oil, swapped out bolt and spring, no change. Took a complete valve from another marker and fired fine.
Any suggestions? I'm about to swap the on/off when I get home from work just to see if there is any issue stemming from that. Thanks in advance.

[nak81783]

Is the powertube threaded onto the rest of the valve properly? Is the oring between the powertube and rest of the valve ok?

[Nobody]

Swapping a valve, does mean that the body is in spec, but you changed out spacers after changing the oring. The leak may be from the wrong sized spacer. Put the .220 back in and go from there. When chasing down leaks, only change 1 part at a time.

After that, try a new oring. Even if tge oring looks fine, it may not be good.

[audioSLAVE]

Swapping a valve, does mean that the body is in spec, but you changed out spacers after changing the oring. The leak may be from the wrong sized spacer. Put the .220 back in and go from there. When chasing down leaks, only change 1 part at a time.

After that, try a new oring. Even if tge oring looks fine, it may not be good.

I always went to the original components before trying different replacement parts. I'll try another o-ring with the .220 spacer. If that doesn't work will I try swapping bottom on/off o-ring. In an ancient post I think Venom suggested swapping that out after nothing else made a difference.

[audioSLAVE]

Is the powertube threaded onto the rest of the valve properly? Is the oring between the powertube and rest of the valve ok?

I'll check when I get home, I don't remember anything suspicious.

[vintage]

if I remember correctly most of mine are running 220 or 225 spacers.

[Menace_AO]

Your problem shouldn't be your on/off, as you've already ruled that out by holding the trigger.

Note that you went down a size, from .220 to .215.

That is loosening the o-ring on the bolt, and you want to tighten it.

Try going to the next size up. That will give more crush to the o-ring and should sort out your problem, or at least lessen it so that you have a sense of going in the right direction.

Let us know how it goes.

[audioSLAVE]

Your problem shouldn't be your on/off, as you've already ruled that out by holding the trigger.

Note that you went down a size, from .220 to .215.

That is loosening the o-ring on the bolt, and you want to tighten it.

Try going to the next size up. That will give more crush to the o-ring and should sort out your problem, or at least lessen it so that you have a sense of going in the right direction.

Let us know how it goes.

I've tried a bunch of different spacers up to .235, there was a necropost where a forum member mentioned trying to swap out the o-ring on the on/off bottom: "Try replacing the on/off BOTTOM o-ring. The o-ring that goes around the stainless steel bottom piece. When you pull and hold the trigger, you seal air off before that o-ring, so when you let off the trigger it will leak, but you'll think it's a PT problem." At this point, I was willing to try anything. I've yet to try a new PT o-ring, haven't had a chance to tinker more yet. I'm wondering if I have a L10 o-ring in the PT, I noticed they had different part numbers on the AGD store.

[audioSLAVE]

I'm thinking the leak is where the powertube screws into the valve? Thoughts based on before and after pics of airing it up without firing?

[vintage]

Tuna has those o rings.

[Menace_AO]

Interesting developments.

Only reason I didn't recommend checking the bottom on/off ring is because you noted air coming from the barrel, which is characteristic of PT ring, and if it were the bottom o/o ring it would sound like it was coming from the frame area.

I'd still think it would be the power tube o-ring. If it's failed, then no amount of squish will help.

Also, highly doubtful you could mistake a level 10 o-ring as they are completely different in size. The o-ring will fit properly down in the hole, snug against the walls.

If you are really curious, switch o-rings between the o/o bottom and the PT. Same o-ring (010), but the leak will change if one is bad.

Or better yet, take the large outside ring from the top and switch it with the PT.


As for the power tube seam, that's weird.

Does it appear that the laser weld has been removed? Maybe someone did an efficiency mod and messed up the o-ring on reassembly? Look at it with a loupe, and you should be able to see pretty clearly if the weld has been compromised.

Hard to tell if the tape is a result of the valve going in and out, or actually pressure, though it definitely looks blown out.

Did you try wrapping, then simply installing and removing (with no gas) to get a baseline sense of what happens to the tape under those conditions?

A leak there would definitely sound more like it is coming out of the barrel.