13XX repair help - continued

13XX repair help - continued

Joined: May 2nd, 2007, 2:21 pm

September 20th, 2011, 5:21 pm #1

Hi all. I posted a little bit ago about my modded 13xx carbine that had stopped holding air not long after receiving it a few years ago.

http://www.network54.com/Forum/275684/t ... 77+carbine

I emailed Tim McMurray to see if he would look at it, but he said he was way too busy and to try again next year, so I thought I would take it apart myself to see what I could see.

So, I took it all apart and not really knowing what I was looking for made the following observations:

there is a small chunk out of the o-ring on the piston

the head/face(?) of the valve doesn't look very good - looks like part of the edge is missing or something. overall the piston and valve were all kind of nicked up looking and not very smooth, but maybe this is normal and I'm sure this didn't happen after being in my gun, as literally the gun wasn't shot maybe 50-100 times before it stopped holding air.

so, I put the gun back together, and it would hold one pump of air for the first 3 shots, and then it stopped holding air altogether again.

when you pump the gun, you hear the air going right out of the barrel.

What do you think?

Thanks for any help!

I'll try to attach pictures to this post.

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Last edited by FlintMan77 on September 20th, 2011, 5:22 pm, edited 1 time in total.
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Joined: February 9th, 2006, 10:35 pm

September 20th, 2011, 5:43 pm #2

That looks nasty.
As bad as all that on the outside looks, the problem is probably inside the valve. If the air is going right out the barrel when you pump then it's the exaust valve that needs fixing. Could be a piece of anything that's missing from the valve face or O-ring got in the valve and is now preventing it from closing tightly.

I plink, therefore I am.
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Joined: November 29th, 2009, 9:53 am

September 20th, 2011, 5:47 pm #3

Hi all. I posted a little bit ago about my modded 13xx carbine that had stopped holding air not long after receiving it a few years ago.

http://www.network54.com/Forum/275684/t ... 77+carbine

I emailed Tim McMurray to see if he would look at it, but he said he was way too busy and to try again next year, so I thought I would take it apart myself to see what I could see.

So, I took it all apart and not really knowing what I was looking for made the following observations:

there is a small chunk out of the o-ring on the piston

the head/face(?) of the valve doesn't look very good - looks like part of the edge is missing or something. overall the piston and valve were all kind of nicked up looking and not very smooth, but maybe this is normal and I'm sure this didn't happen after being in my gun, as literally the gun wasn't shot maybe 50-100 times before it stopped holding air.

so, I put the gun back together, and it would hold one pump of air for the first 3 shots, and then it stopped holding air altogether again.

when you pump the gun, you hear the air going right out of the barrel.

What do you think?

Thanks for any help!

I'll try to attach pictures to this post.

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when storing the gun did you store it with air in the valve??
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Joined: March 1st, 2002, 12:22 am

September 20th, 2011, 6:17 pm #4

Hi all. I posted a little bit ago about my modded 13xx carbine that had stopped holding air not long after receiving it a few years ago.

http://www.network54.com/Forum/275684/t ... 77+carbine

I emailed Tim McMurray to see if he would look at it, but he said he was way too busy and to try again next year, so I thought I would take it apart myself to see what I could see.

So, I took it all apart and not really knowing what I was looking for made the following observations:

there is a small chunk out of the o-ring on the piston

the head/face(?) of the valve doesn't look very good - looks like part of the edge is missing or something. overall the piston and valve were all kind of nicked up looking and not very smooth, but maybe this is normal and I'm sure this didn't happen after being in my gun, as literally the gun wasn't shot maybe 50-100 times before it stopped holding air.

so, I put the gun back together, and it would hold one pump of air for the first 3 shots, and then it stopped holding air altogether again.

when you pump the gun, you hear the air going right out of the barrel.

What do you think?

Thanks for any help!

I'll try to attach pictures to this post.

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then pump it

does sound like foriegn material on or in the valve


dr_subsonic's pneumatic research lab

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Joined: February 25th, 2011, 10:27 pm

September 20th, 2011, 9:45 pm #5

Hi all. I posted a little bit ago about my modded 13xx carbine that had stopped holding air not long after receiving it a few years ago.

http://www.network54.com/Forum/275684/t ... 77+carbine

I emailed Tim McMurray to see if he would look at it, but he said he was way too busy and to try again next year, so I thought I would take it apart myself to see what I could see.

So, I took it all apart and not really knowing what I was looking for made the following observations:

there is a small chunk out of the o-ring on the piston

the head/face(?) of the valve doesn't look very good - looks like part of the edge is missing or something. overall the piston and valve were all kind of nicked up looking and not very smooth, but maybe this is normal and I'm sure this didn't happen after being in my gun, as literally the gun wasn't shot maybe 50-100 times before it stopped holding air.

so, I put the gun back together, and it would hold one pump of air for the first 3 shots, and then it stopped holding air altogether again.

when you pump the gun, you hear the air going right out of the barrel.

What do you think?

Thanks for any help!

I'll try to attach pictures to this post.

[/IMG]

[/IMG]

[/IMG]

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As bad as it looks problem probably lies within the valve... I've seen worse parts that still worked...
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Joined: January 4th, 2010, 4:13 am

September 20th, 2011, 10:47 pm #6

Hi all. I posted a little bit ago about my modded 13xx carbine that had stopped holding air not long after receiving it a few years ago.

http://www.network54.com/Forum/275684/t ... 77+carbine

I emailed Tim McMurray to see if he would look at it, but he said he was way too busy and to try again next year, so I thought I would take it apart myself to see what I could see.

So, I took it all apart and not really knowing what I was looking for made the following observations:

there is a small chunk out of the o-ring on the piston

the head/face(?) of the valve doesn't look very good - looks like part of the edge is missing or something. overall the piston and valve were all kind of nicked up looking and not very smooth, but maybe this is normal and I'm sure this didn't happen after being in my gun, as literally the gun wasn't shot maybe 50-100 times before it stopped holding air.

so, I put the gun back together, and it would hold one pump of air for the first 3 shots, and then it stopped holding air altogether again.

when you pump the gun, you hear the air going right out of the barrel.

What do you think?

Thanks for any help!

I'll try to attach pictures to this post.

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Most of the marks nicks etc. are tool marks from where someone has had the gun apart in the past
maybe when the mods where done.

I have had similar air pressure problems lately and after a good cleaning with the valve out and
disassembled, a few q tips, an alcohol rinse, new lube and o rings all is well, It is not as
hard as it sounds, just keep hard metal tools and abrasives out of the inside of the valve, and
deburr the pump tube before reassembly. As long as the sealing surfaces aren't nicked, she should
hold air.

I BRAKE FOR BISCUITS
and TRAINS
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Joined: November 5th, 2008, 8:23 pm

September 21st, 2011, 2:51 am #7

average putting in that airgun with those 50 to 100 shots?
Your oil wiper on the piston looks cooked. likely from the heat of
excessive pumping.
Also, you valve face so damaged that part of the front edge is actually missing.
That in itself would destroy any o-ring.
And the marks on the side of the piston.
Did you put them there with pliers or a wrench?
If you didn't, then you've gotten some foreign material inside the pump tube at one time or another and it scratched the side of the piston.
Problem is, if the piston looks like that on the side, the inside wall of the pump tube is probably just as bad, if not worse.
Before you put it back together I would suggest you take a very good look with a strong light at the inside of the pump tube where the piston travels.
If its scratched very bad, you'll need a new one, or your o-rings won't last very long at all.
The air escaping out the barrel is most likely some of all that broken bits of brass hung up under your exhaust valve.
You'll be lucky if the valve doesn't need replacing.
If its been damaged anywhere around the sealing end, you'll need a new one.
Check out this picture of a cut-away view of a stock valve.
It will help you get everything back in like it came out.



Take the valve apart, paying special attention to how everything fits inside it and clean it very good and re-oil lightly with straight non-detergent 30w motor oil.
I'd also put a new oil wiper on that piston before putting it back together if it was me.
Hope this helps.
Good luck
Ray
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Joined: May 2nd, 2007, 2:21 pm

September 21st, 2011, 4:12 pm #8



I usually only pumped it 5 to 10 times.

I never pumped it over 15 - and only pumped it up to 15 a few times for the chrony test - I was assured that 15 pumps was perfectly fine - and the gun dumped all 15 pumps each time no problem.

I'm pretty sure that the shape that everything is in now - is how it was when I received it.

Those nicks in the brass piston were definitely already there as was I think that little nick in the 0-ring.

I have no idea what the front of the valve looked like when I got it - but it does look ugly now - it looks like that it was machined too thin or something - or just very poorly - that face is very rough from tool marks - like when it was made or something.

I didn't use any tools when taking apart the gun - so any nicks or marks would have already been there.

I forgot to mention that when I took it apart before, I did unscrew the valve - oh yeah, and those tool marks were already there - I unscrewed it by hand when I did it. I didn't take any pictures of the inside of the valve though as I didn't see much to look at.

I'll try taking it all apart again and cleaning everything and replacing the o-rings, and see what happens.

How do I clean out the valve though - I know i can unscrew it. and the one end has that pin that must release the air - and the other side has the little hole in the outside face of it - but then I don't see how to take it apart any further from there.

Thanks for your help guys. I assure you - as far as I know I did NOT abuse this gun at all.

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Joined: May 2nd, 2007, 2:21 pm

September 21st, 2011, 4:16 pm #9

average putting in that airgun with those 50 to 100 shots?
Your oil wiper on the piston looks cooked. likely from the heat of
excessive pumping.
Also, you valve face so damaged that part of the front edge is actually missing.
That in itself would destroy any o-ring.
And the marks on the side of the piston.
Did you put them there with pliers or a wrench?
If you didn't, then you've gotten some foreign material inside the pump tube at one time or another and it scratched the side of the piston.
Problem is, if the piston looks like that on the side, the inside wall of the pump tube is probably just as bad, if not worse.
Before you put it back together I would suggest you take a very good look with a strong light at the inside of the pump tube where the piston travels.
If its scratched very bad, you'll need a new one, or your o-rings won't last very long at all.
The air escaping out the barrel is most likely some of all that broken bits of brass hung up under your exhaust valve.
You'll be lucky if the valve doesn't need replacing.
If its been damaged anywhere around the sealing end, you'll need a new one.
Check out this picture of a cut-away view of a stock valve.
It will help you get everything back in like it came out.



Take the valve apart, paying special attention to how everything fits inside it and clean it very good and re-oil lightly with straight non-detergent 30w motor oil.
I'd also put a new oil wiper on that piston before putting it back together if it was me.
Hope this helps.
Good luck
Ray
also, looking at your image again - of the valve.

so on the right side of the valve (from your picture) what is that rectangular thing that looks like its floating on the inside of it. does that come out? what if I applied some pressure from an air hose into the little pin hole?




if this doesn't work, should I consider replacing the valve and piston? or have there been other mods done that now require the use of this combination only?




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Joined: November 5th, 2008, 8:23 pm

September 21st, 2011, 6:34 pm #10

thing is a check valve.
And in fact, its round and slides up and down inside the valve.
Its held in place by the valve spring which keeps it shut over the little hole in the end of the valve to hold the air in it.
You overcome the springs pressure by pumping the forearm and the piston pushes the air in the little hole.
The other end of the valve spring holds the exhaust valve shut until the hammer hits it and opens the valve to release the air into the exhaust port and out the barrel.
Hope this helps.
Ray
P.S. If it worked before, hopefully cleaning it out and putting it back
together will fix the problem without having to buy a new one.
Besides, the brass valves are the good ones.
The new valves are all aluminum.
Last edited by ray1377 on September 21st, 2011, 6:36 pm, edited 1 time in total.
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