Author Topic: 257 Texan Valve Lock or Something Else?  (Read 292 times)

steveoh

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257 Texan Valve Lock or Something Else?
« on: November 15, 2019, 03:03:14 PM »
257 Texan Valve Lock or Something Else?

My Texan acted strange the last time I was shooting at Kevin's, and today I shot it once in the backyard and it acted strange again.

1. Texan has about 2k of air in it.
2. Power wheel is about 1/4 power setting.
3. I attach the hose from my big tank to the Texan and fill to 3k as per the Wika Gauge on the tank.
4. I look at the Texan and the gauge has not moved from 2k. What?
5. I load the gun and shoot at my target on the hill that is about 20" thick of shredded rubber in a 2x6 framed all around box.
6. Fill the Texan again, and same thing happens. Tank Gauge registers 3k, but gauge on rifle measures 2k.
7. I scratch my head, and open the breach and go back to the tank to try filling again, only this time the tank gauge is equalized with the rifle gauge. Double What?
8. I open the valve on the tank and fill to 3k, and this time the tank and rifle gauges agree with each other.

Any idea what is going on?  Is this the infamous Texan Valve Lock? or something else, or a combination of things?

And it's Turkey Season, damnit.


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Alan

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Re: 257 Texan Valve Lock or Something Else?
« Reply #1 on: November 15, 2019, 03:10:29 PM »
Dirt!

Depressurize the whole mess, and replace the gauge. I have had that happen, and that is why I bought expensive ones!

You can buy cheap Chinese 23 mm gauges, in small quantities (25 to 50 units) for under $4 each!! Good 23 mm class 4 Wika gauges cost about $60 each!
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Alan

I have an Omega compressor. If you're a fellow Guild member, and you pass through Roswell, NM, I'll fill your portable tank as a courtesy.

rsterne

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Re: 257 Texan Valve Lock or Something Else?
« Reply #2 on: November 15, 2019, 06:48:22 PM »
If your gun is shooting at normal power/trajectory it is NOT valve lock.... As Alan suggests, I would guess a gauge problem on the gun....

Bob
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steveoh

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Re: 257 Texan Valve Lock or Something Else?
« Reply #3 on: November 16, 2019, 04:30:37 AM »
If your gun is shooting at normal power/trajectory it is NOT valve lock.... As Alan suggests, I would guess a gauge problem on the gun....

Bob

I think that it’s most likely more than a gauge.

At Kevin’s during our last shoot, the Texan appeared to be filled to 3k. But initial shots were low power. The sound indicated lower power, and the bullet dropping two feet at
at the target also indicated low power. I had changed nothing on the rifle in between outings other than cleaning the barrel.

I fiddled with the power wheel the last shoot and increased the power way way up and the rifle got back it’s “zing”. Turned it back to the normal setting which did not have the correct power. I ended up one full revolution on the power wheel to get back to  the same point of impact at 100 yards. Then I was able to get reasonably consistent strings at 100 yards, and qualified for NUAH.

I initially suspected the fill nipple valve wasn’t opening. And now I suspect the gauge as well, but I am suspicious that there is more going on.

Will depressurize, swap out the gauge, pull the fill nipple and inspect and clean. Then maybe it’s time to put in a new stock hammer spring.

And yep time to run it by the chrony and not rely on my ears.
« Last Edit: November 16, 2019, 04:35:38 AM by steveoh »
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Steelhead

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Re: 257 Texan Valve Lock or Something Else?
« Reply #4 on: November 16, 2019, 05:58:24 AM »
Not being a techy I'm hesitant to offer any insight, but it seems as if the check valve is sticking. Inconsistent fills and not hearing the 'click' of the valve opening makes me think that. A hammer issue wouldn't be related to fill pressure, correct?

My Armada would do the same once in a while.
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Nicesurprice

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Re: 257 Texan Valve Lock or Something Else?
« Reply #5 on: November 16, 2019, 07:53:42 AM »
Compromized gauge?
Sometimes the valve in the quick fill blocks.

Thats why we use delrin valves in the fill plug.
Or use minimess systems for match-grade rifles.
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rsterne

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Re: 257 Texan Valve Lock or Something Else?
« Reply #6 on: November 16, 2019, 08:27:16 AM »
If the velocity is lower, then it could be valve lock.... I understand that the hammer spring in the Texan suffers from "fatigue", or at least it gets shorter with use.... That usually indicates the spring coils are too widely spaced, and when compressed past their yield point the spacing decreases.... This is not really fatigue, but the spring taking a "set"....

I intentionally set all my hammer springs before the first installation.... I put them on a rod that is close to the ID and collapse them fully, all the way to coil bind.... Most springs will get shorter.... ie they will not rebound to their original LOA.... The great thing about doing that, is that once they are compressed to coil bind, that in use they won't continue to get shorter.... This means that you can rely on preload adjustments (eg. your "power wheel" ) to not change over time....

What I don't know about the Texan hammer spring is, if you can follow this procedure without ruining the spring.... It you set it completely and then go to install it, it may be so short that you can't even get the gun to shoot at maximum power on the adjuster.... To me, that just means the spring is the wrong one.... but it could really spoil your day if you have some shooting planned....  :-[

Bob
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steveoh

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Re: 257 Texan Valve Lock or Something Else?
« Reply #7 on: November 16, 2019, 09:00:08 AM »
Not being a techy I'm hesitant to offer any insight, but it seems as if the check valve is sticking. Inconsistent fills and not hearing the 'click' of the valve opening makes me think that. A hammer issue wouldn't be related to fill pressure, correct?

My Armada would do the same once in a while.

I suspect it also. I have some stainless spares and will install one. Also have spare gauges that Alan sent me. Will put in one of those also. I do have a little larger gauge on order though.
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steveoh

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Re: 257 Texan Valve Lock or Something Else?
« Reply #8 on: November 16, 2019, 09:04:12 AM »
If the velocity is lower, then it could be valve lock.... I understand that the hammer spring in the Texan suffers from "fatigue", or at least it gets shorter with use.... That usually indicates the spring coils are too widely spaced, and when compressed past their yield point the spacing decreases.... This is not really fatigue, but the spring taking a "set"....

I intentionally set all my hammer springs before the first installation.... I put them on a rod that is close to the ID and collapse them fully, all the way to coil bind.... Most springs will get shorter.... ie they will not rebound to their original LOA.... The great thing about doing that, is that once they are compressed to coil bind, that in use they won't continue to get shorter.... This means that you can rely on preload adjustments (eg. your "power wheel" ) to not change over time....

What I don't know about the Texan hammer spring is, if you can follow this procedure without ruining the spring.... It you set it completely and then go to install it, it may be so short that you can't even get the gun to shoot at maximum power on the adjuster.... To me, that just means the spring is the wrong one.... but it could really spoil your day if you have some shooting planned....  :-[

Bob

I’m the second owner. No telling how many bullets he shot. Add in the gazillion bullets I’ve gone through, it’s probably time to replace the hammer spring.

AirForce has been zero help. A tech was supposed to call me back but a week later, all quiet on the Texas front.  :(

Looks like the guys in South Africa sell a kit of three springs. The reviews are mixed however.
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sixshootertexan

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Re: 257 Texan Valve Lock or Something Else?
« Reply #9 on: November 16, 2019, 09:23:39 AM »
Sounds like it's time for a total disassemble. Replace all seals, springs, and gauges.
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steveoh

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Re: 257 Texan Valve Lock or Something Else?
« Reply #10 on: November 17, 2019, 03:19:52 PM »
I drained my Texan’s tank and removed the fill nipple and the gauge. I found suspect black Teflon tape bits all over.

I have a couple stainless fill nipples on hand and compared to the original Texan they are or appear to be more robust and sophisticated in their machining. Wrapped the threads with yellow Teflon tape and easily installed it.

There is a box of gauges that Alan had sent to me that I have gleefully picked through and used to fix crappy tank and compressor gauges. Salute!

I found several Airgun gauges in the box and picked out the purtiest one and wrapped it with yellow Teflon tape and filled the Texan tank to about 2k. Leak. Damnit. I tried tightening a little but that didn’t fix it. So drained tank again and saw that my taping job the first time around was piss poor. I was way more careful the second time. Filled to 1k and no leak. Filled to 2k and no leak. Reinstalled the tank, and filled to 3k and so far it’s holding.

I noticed at the beginning of the exercise that the simple fill nipple had a very difficult to move pin. Flip it over and you see the pin has a star head screw and a slot. Even off the tank it was sticky and hard to turn. For sure it is wonky and a source of some of my problems.

Tomorrow I’ll check to see if the tank held air over night and I’ll set up the chrony and see if I get my old consistent shooting.

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Bullfrog

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Re: 257 Texan Valve Lock or Something Else?
« Reply #11 on: November 18, 2019, 08:49:03 PM »
My Texans do this. Its the fill nipple sticking. In the case of my guns, it happens when the gun has sat a long time without being filled. I have to jack the PSIs high on the hose side to break the nipple free. Usually a hair above 4000psi.

steveoh

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Re: 257 Texan Valve Lock or Something Else?
« Reply #12 on: November 18, 2019, 09:37:29 PM »
My Texans do this. Its the fill nipple sticking. In the case of my guns, it happens when the gun has sat a long time without being filled. I have to jack the PSIs high on the hose side to break the nipple free. Usually a hair above 4000psi.

Ah hah!

Thanks this is all starting to make sense. We’ll see how the new fill nipple works.
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Nicesurprice

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Re: 257 Texan Valve Lock or Something Else?
« Reply #13 on: November 18, 2019, 10:32:57 PM »
My Texans do this. Its the fill nipple sticking. In the case of my guns, it happens when the gun has sat a long time without being filled. I have to jack the PSIs high on the hose side to break the nipple free. Usually a hair above 4000psi.

Ah hah!

Thanks this is all starting to make sense. We’ll see how the new fill nipple works.

Just make a shutoff valve yourself.
A small piece f delrin is all you need.
Those original valves with O-ring gives a lot spread in pressure.
Just put a cone shape piece f delrin in the original foster-plug.
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