Canadian Airgun Forum :: Help leaking valve?

Got the QB back to together for saturday :wink:

so I guess the Rvd&Sniper FT is on haha

The teflon valve stem material is tough as nails, took some work to get it lapped properly but it went good.. I first tried to lap it in by hand by putting some lapping compound on the stem which was slid through the back half of the valve body.. It was taking forever by hand so I chucked the stem up in the drill press and lapped it on the lowest speed with light pressure.. worked like a charm..

chucked up in the drill press

1st attempt by hand lapping, not too much happened to the material but then again I was being cautious.

2nd stage lapping with drill press on lowest setting.. Starting to make an impression in the teflon now..

3rd stage lapping with drill press and lapping compound, just about done.. You can clearly see the impression is made on the stem.

After the 3rd stage with lapping compound I finished it off using toothpaste.. Toothpaste works nice for a mild lapping compound, it's something we use on our slot cars to lap new gears in so I know it works well.. After the lapping was done I finished off the stem with a nice taper and took the O.D down 1/2 way up the teflon.. It's alot lighter than the factory stem so I see why this valve increases velocity, it lifts off the seat a little more from the striker hit.

Author:	M3ga3T [ Mon Mar 10, 2014 5:30 pm ]
Post subject:	Help leaking valve?
Hey guys, I've been having trouble with my Concept holding air. When drilling out ports, I didn't damage the valve stem groove for the seal. But I'm having trouble after reassembly. Sometimes it won't even hold up against the first initial pump and I can hear air getting sucked in and out of the valve side. Has anyone had this kind of issue? Where the valve stem and plastic seal need air pressure from the pressurized side in order to seal the valve completely. But after assembling and trying to pump, it either fails first pump or as the pressure goes up. I did notice a tiny tiny mark on the valve stem seal (hard, black plastic). Can that be causing it? Or should I use something to hammer lightly the valve stem and it's seal into the valve groove where it goes to seal completely until air gets in there? Or try to get a new valve stem and seal (is delrin?) machined for a more snug fit to take away any slop the current seal has? Any help much appreciated!

Author:	Ace [ Mon Mar 10, 2014 5:55 pm ]
Post subject:	Re: Help leaking valve?
M3ga3T wrote: I did notice a tiny tiny mark on the valve stem seal (hard, black plastic). Can that be causing it? Yes! sound like you have a little slice on the seal, that's all it needs to not hold air especially if its a delrin seal all it needs is a little slice or something where it sits on the groove and it won't seal properly, take it out and look at it under a magnifying glass and check the groove.

Author:	M3ga3T [ Mon Mar 10, 2014 6:02 pm ]
Post subject:	Re: Help leaking valve?
Thanks Ace! It is a tiny mark not even 1 mm by 1 mm. It's in the middle of the seal and the groove for it in the valve isn't damaged thankfully. So, , a new stem is my only hope That's what I get for over-tinkering. My gf even tells me I tear into them too much. I should take her advise

Author:	M3ga3T [ Mon Mar 10, 2014 6:08 pm ]
Post subject:	Re: Help leaking valve?
Another question, how do you clean the valve and other internals after an hour of fiddling with the internals? Because I obviously got sweat etc. on the valve and it's internals. I think I've read silicone spray for the tank and silicone grease for the valve? I know I should probably use latex/rubber gloves when dealing with the internals of a pcp

Author:	barbas929 [ Mon Mar 10, 2014 6:36 pm ]
Post subject:	Re: Help leaking valve?
I too once had the same problem and another member told me to put the stem(also a hard plastic material) in a drill and add a little toothpaste to both the valve body and stem and slowly turn the stem while in the body applying a little pressure...worked like a charm and still holding for the last 2years...i'm guessing it would create another reseal groove on the stem and body Hopefully it might work for your gun and worth a shot

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Author:	rrdstarr [ Mon Mar 10, 2014 7:03 pm ]
Post subject:	Re: Help leaking valve?
You can order a rebuild kit direct from brocock.uk. I have one sitting here, but it is going with gun to Gerard to be tinkered with! http://www.brocockdirect.co.uk/products.php?product=BROCOCK-COMPLETE-PCPC-SEAL-KIT

Author:	Ace [ Mon Mar 10, 2014 7:04 pm ]
Post subject:	Re: Help leaking valve?
M3ga3T wrote: Another question, how do you clean the valve and other internals after an hour of fiddling with the internals? Because I obviously got sweat etc. on the valve and it's internals. I think I've read silicone spray for the tank and silicone grease for the valve? I know I should probably use latex/rubber gloves when dealing with the internals of a pcp when ever I work on valves, like when I angle the transfer port and so on I wash them out with water and then blow them out with air to make sure no metal filling or any debris are still there

Author:	stephane5813 [ Mon Mar 10, 2014 7:13 pm ]
Post subject:	Re: Help leaking valve?
I use Dust Blaster from dollarama to get rid of the particules Stephane

Author:	M3ga3T [ Mon Mar 10, 2014 7:16 pm ]
Post subject:	Re: Help leaking valve?
Thanks Ace! That's a good idea, I have just been trying to wipe all over with a clean cloth. Thanks Rick! I have been browsing their site lately and I would definitely order one. They have a lot of neat stuff for their guns on there huh? And thanks Barbas929! So stick the metal stem side in a drill and using pressure, add toothpaste to the black, plastic stem part? I am willing to try anything! I really hate having a gun torn down due to not being able to work/shoot properly Thanks Stephane! I have a can of similar stuff but just wasn't sure if I could use it in there. Another question, is there also other tricks and tips to trying to repair the plastic valve stem seal for your common man with no lathe or other heavy duty equipment? Just some hand tools and a drill set Although, push come to shove, I will get a new valve stem. I just hate waiting weeks for things to happen. Bad enough my poor 97 has been gone since December

Author:	Penage Guy [ Mon Mar 10, 2014 7:53 pm ]
Post subject:	Re: Help leaking valve?
M3ga3T wrote: That's what I get for over-tinkering. My gf even tells me I tear into them too much. I should take her advise M3ga3T wrote: I really hate having a gun torn down due to not being able to work/shoot properly Get your gun fixed and listen to your girlfriend.

Author:	M3ga3T [ Mon Mar 10, 2014 8:25 pm ]
Post subject:	Re: Help leaking valve?
Yes I will Penage!! As soon as it's up and running and holding air again, I am not touching the internals again for a very long time! Working on springers is soo much easier for me! Only gotta worry about 2 seals and one spring!

Author:	doublevision [ Mon Mar 10, 2014 8:40 pm ]
Post subject:	Re: Help leaking valve?
rvd wrote: Got the QB back to together for saturday so I guess the Rvd&Sniper FT is on haha The teflon valve stem material is tough as nails, took some work to get it lapped properly but it went good.. I first tried to lap it in by hand by putting some lapping compound on the stem which was slid through the back half of the valve body.. It was taking forever by hand so I chucked the stem up in the drill press and lapped it on the lowest speed with light pressure.. worked like a charm.. chucked up in the drill press 1st attempt by hand lapping, not too much happened to the material but then again I was being cautious. 2nd stage lapping with drill press on lowest setting.. Starting to make an impression in the teflon now.. 3rd stage lapping with drill press and lapping compound, just about done.. You can clearly see the impression is made on the stem. After the 3rd stage with lapping compound I finished it off using toothpaste.. Toothpaste works nice for a mild lapping compound, it's something we use on our slot cars to lap new gears in so I know it works well.. After the lapping was done I finished off the stem with a nice taper and took the O.D down 1/2 way up the teflon.. It's alot lighter than the factory stem so I see why this valve increases velocity, it lifts off the seat a little more from the striker hit. hope that clears it up for you, I'm going to be doing this myself soon...

Author:	rsterne [ Mon Mar 10, 2014 8:45 pm ]
Post subject:	Re: Help leaking valve?
Try this fix.... When the valve is out of the gun and everything is clean inside, put the poppet in place in the valve body and then chuck the stem in a reversible portable electric drill.... Pull gently on the stem with the drill, and run the drill a couple seconds in each direction, and repeat twice.... Unchuck the stem and remove it from the valve and inspect both the seat and poppet under magnification.... You are looking for a CONTINUOUS shiny ring on both parts.... If you see a gap or obvious dent where they were rubbing, it won't seal.... Try it again, pulling a bit harder on the drill.... If you still have no luck use a dab of toothpaste or Solvol Autosol (metal polish) and try again.... DON'T pull too hard, or run the drill too fast or too long which will get the hot and could melt the poppet face.... Clean the parts thoroughly and test with the drill to check for the continuous shiny seat again.... I have never had a poppet I didn't fix that way.... so good luck !!! Bob

Author:	DerekVinyard [ Mon Mar 10, 2014 9:09 pm ]
Post subject:	Re: Help leaking valve?
Lapping with whitening toothpaste and comet/ajax powder works well against the valve seat. Leaving the stem under pressure against the valve stem in a press overnight helps. Hitting it with a burst of pressure when first installed often get it to seat (and leave it for a couple days) a hand pump is way too gentle to get it to seal...

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Author:	M3ga3T [ Tue Mar 11, 2014 2:06 am ]
Post subject:	Re: Help leaking valve?
Thank you everyone for your help!!! I am going to try the toothpaste technique as that's all I am capable of atm. Is this the way to do it?- Stick this part in the drill (metal stem side or plastic side without spring?) Then put in the groove/valve seat where it would normally go (picture below), then while pulling the valve stem in and out of the valve with the drill going and adding toothpaste?