68 air valve being retarded

[fhawkeye]

I've been fixing mags at my local field for a while now and this is the first one I haven't got the slightest clue on why it's not working. 68 AIR valve that stutter shoots, doesn't leak down the barrel on gas up, leaks down the barrel when fired then doesnt leak down the barrel when fired, fires a shot on pull and release sometimes. seems to be a different combination whenever it's aired up. I replaced all the O-rings in the valve by now.

The only thing that stands out to me is that the on/off doesn't stick out as much as the one on my minimag air valve does.

Tried the common practice things, it will tend to leak heavily down the barrel on trigger release and then not so much (but still leaks) when trigger is held.

[Ando]

Take a look at the wear on your sear and bolt.

If it's leaking when you hold the trigger down then you might need to take another look at your on/off orings.

[Coralis]

Does this have the old style on/off and if so is it installed correctly.

[secretweaponevan]

Go to basics. If it leaks down the barrel with the trigger held, you have a leak in your on/off.

This can be due to:
bad o-ring(s)
on/off pin in upside down
missing rail bushing <-often overlooked

Solve your on/off problem and diagnose from there.

[fhawkeye]

Everything looks good, the O-rings are fresh just replaced the teflon and on/off body seals, the on/off parts are installed correctly with the flat part of the pin up in the valve and the round nob part down where the sear hits (like here)

I even tried a whole different rail with a better looking sear and bushing.

I might have overlooked the bolt when I tried a bunch of stuff I'll double check when I get home.

[fhawkeye]

Got it!

the on/off was faulty, the seals were fine, the on/off assembly itself was wrong, I replaced the brass piece with the one from my mini-mag and it worked. thanks guys

[Spider-TW]

Got it!

the on/off was faulty, the seals were fine, the on/off assembly itself was wrong, I replaced the brass piece with the one from my mini-mag and it worked. thanks guys

Good deal, but I'm really curious as to the piece that was in there. Could you give us a pic?

[Slimpb]

Im interested as well to know what was wrong with it? i know its not the standard peice since it doesnt have the x on it but its still part of the on off

[fhawkeye]

Actually I don't have it anymore i gave the gun back to the kid, I'll surf around for the pic but the explanation I can give is that 1 side is flat, the other side thins out and has a lot of little holes on the side.

[fhawkeye]

Actually I don't have it anymore i gave the gun back to the kid, I'll surf around for the pic but the explanation I can give is that 1 side is flat, the other side thins out and has a lot of little holes on the side.

the brass piece in the on/off assembly was the bottom left one, I couldn't see an physical damage but replacing it is what made it work.

[Ando]

I've only seen one of those tops before. After fixing the guys gun I keeped it and brought it to TB4 to show Tuna and ask WTH it was. He pretty much said they weren't the best on/off tops and were known to starve the valve. Also, most of the time people install them upside down

[Slimpb]

Actually I don't have it anymore i gave the gun back to the kid, I'll surf around for the pic but the explanation I can give is that 1 side is flat, the other side thins out and has a lot of little holes on the side.

I Know I'm looking at it and I will be replacing it but I can't figure out why it would be different I'll see if I can take some pics and put them up

Got it [IMG][/IMG]

[Slimpb]

I've only seen one of those tops before. After fixing the guys gun I keeped it and brought it to TB4 to show Tuna and ask WTH it was. He pretty much said they weren't the best on/off tops and were known to starve the valve. Also, most of the time people install them upside

I dont mind starving it since im poor but i beleive he had it installed the right way but which would be the right way

[Ando]

I dont mind starving it since im poor but i beleive he had it installed the right way but which would be the right way

Don't get me lying to ya bro, I don't have the slightest clue which way is up on it. I thought it was some brass junk piece they put in cause they lost the original.

[Spider-TW]

I dont mind starving it since im poor but i beleive he had it installed the right way but which would be the right way

I can see it holding air either way, but the holes would have to face towards the body of the on/off, away from the top o-rings to get any flow. That would also match the direction relative to the other tops in fhawkeye's pic.

Some drilling and filing might help, but the thickness of the top section almost looks like it would be both too high or too low, depending on how you put it in. Just too short overall maybe.