Bam B50 leak upon re-assembly question

[carefulshot]

I got a new spring for the valve stem.  I got everything in and tested the tube to see if it would hold air.  This is from 0 psi.  As I'm pumping air is streaming out of the port where air would blast into the barrel.  I thought this may be because the spring was to light so I put the old spring back in, but had the same problem, why isn't it sealing?

[Ribbonstone]

May seem obvious...but is the striker cocked or pressing against the valve stem?

[carefulshot]

May seem obvious...but is the striker cocked or pressing against the valve stem?

No sir the whole thing is disassembled

[Ribbonstone]

Yeah...I test mine pretty much as a naked air tube too...if it leaks, saves a lot of disassembly.

Are right....if it leaks out the port, then it's the valve stem not sealing.

Could be that the valve stem has a problem...either kept from sealing or with some bit of gunk from the tanke down keeping it from mating up.

OR

It could be the valve stem seal just needs 300-600psi to seal, under that and it leaks.

From "0", often need a sudden blast of air rather then the slow trickle that pump filling gives (even if you pump like a mad-man).

When I was also bulk filling other rifles with co2, would sometimes have to resort to co2 for a no-seal PCP valve stem.  It's a blast of 900psi (more or less).  If that didn't do it, would know that I just had to go back inside and see what's wrong.


So, if you are filling with a pump, may be that you just can't get a "right now" blast of 500-800psi.  Even then, may not truly seal until 1000psi, but will normally slow the leak so a pump can gain on it.

Which helps not at all if all you have at hand is a pump.


NOW, I'll tell a tale that I've no first hand experience with, but was told to me as true.  Not a BAM, but another simple PCP with the same problem.  Valve stem wanted several 100 psi to start sealing well enough for a pump to gain pressure (and would totally seal and not leak by about 500psi).  Problem was getting that first 200-250psi.

What this guy claims to have done was to tightly cork the transfer port (he made a skinny short "cork" out of  the tip end of a car tire plug).  Pumped like crazy until the cork "popped". When it popped, the valve "slammed" shut (likely 200psi) to at least a partial seal, and he could gain on the leak.

Never tried it...first thought it was kind of a fish-story...but thinking about it, can't help but wonder if he told the truth as I can't think of why it couldn't work.

[demarisl]

Call http://ultimate-paintball.com/DavenportIowapaintball and see if they are willing to fill your B50.  I get my 4500 PSI Great White filled at my local paintball range for $5 while I wait.  Just have to let them know I'm coming so they can have the compressor running. 

[carefulshot]

Hahaha oh boy, I'll try to clean it out first then buy a bottle of wine . Seriously though I'll look into it, that is very helpful thank you.

[carefulshot]

Call http://ultimate-paintball.com/DavenportIowapaintball and see if they are willing to fill your B50.  I get my 4500 PSI Great White filled at my local paintball range for $5 while I wait.  Just have to let them know I'm coming so they can have the compressor running.

Oh perfect!

[demarisl]

Matt, did you get your leak/pressurization problem resolved?

BTW, I'm just north of Cedar Falls and if you ever get up this way, I have a 100 yard range with a solid bench and plenty of air.

Larry

[carefulshot]

Hey Larry,

I have not gotten this fixed yet.  I re assembled everything and had it quick filled to 1500 psi and it kept a slow leak. I just took the whole valve out and checked all the o rings and put the valve assembly together outside of the gun to make sure all the seals were good. Now I left the old rings in, they honestly did not look damaged or bad. After putting the assembly back in I'm having the same problem.  I should also say I did all of this because after I had it filled it lost all of its air lol so I didn't need to worry about de-pressurizing. I have 2000 grit sand paper and I lightly sanded the delrin pin on a washer to smooth it out, wiped out where it contacts. I still have my leak.

Not sure what to do now, I'm guessing it is the firing pin seal, but I don't know where to get a better one.

[carefulshot]

Matt, did you get your leak/pressurization problem resolved?

BTW, I'm just north of Cedar Falls and if you ever get up this way, I have a 100 yard range with a solid bench and plenty of air.

Larry

[carefulshot]

I should say also that it leaks into the breach too

[Motorhead]

Are you SURE leak is happening around POPPET ?
If you can isolate exactly where it is occurring, surely we can assist in helping you fix it.

[carefulshot]

Nope I couldn't say for sure, but the fact that air is leaking out of the hole where it would go into the barrel and through to the breach around the pin, that is my best educated guess

[carefulshot]

My original goal was to get ahold of big Ed and send it in but he doesn't seem to be taking projects right now

[Motorhead]

My original goal was to get ahold of big Ed and send it in but he doesn't seem to be taking projects right now

I'm on the west coast ... but could fix it no problem.
If your able to tear it back down, do so having the valve assembly in hand. Remove end cap and spring then attach a drill to the exposed poppet stem.  With modest to low speed SPIN the valve s poppet stem while drawing pressure reward to burnish poppet head into the seat.
Reverse direction a few times.  Clean up and reassemble, dollars to donuts leaks no more. 

[demarisl]

Matt,

I think I had the same maddening leak this summer with my B51.  Finally narrowed it down to the #006 o-ring (part #23).  With part #24 screwed in tight enough to hold it in place, the poppet would bind.  Loosened so the poppet moved freely, it leaked.  Finally took the valve to my local hardware store and found a thin washer that would fit and hold the o-ring in place when part #24 was loosened to allow the poppet free movement.  Mine hasn't leaked since.  Worth a try as you will probably get change for your nickel when you pay for the washer.

Larry

[Buldawg76]

Matt
If its still leaking try what Motorhead said to do then assemble it so you can pressurize it with as much pressure as possible ( 800 to 1000 ) and use the hammer to drop into the tube to fire the valve several times to see if using the air pressure to force the poppet shut against the seat may create a set groove in the poppet and seal  it up . I have had to do this on some of my QBs and 60cs to get the poppet to seat at first and then shooting the gun creates its own good sealing seat in the poppet face.

Mike 

[carefulshot]

Hey guys I will try both of those