RT Pro running away

I 'm having trouble with my RT Pro going into run away. It hasn't given me any problems for years and now it is running away. I have an X-Valve with LX and ULT. I don't remember the settings for the X-valve, but the ULT has 4 shims. Additionally, I'm running it with a Centerflag Products Hyperframe.

I tried removing a couple of shims from the ULT, but then it wouldn't fire. Replaced the shims and running away. I then tried a longer bolt spring because it seems like the bolt might not be resetting and then it wouldn't fire. I increased the valve pressure and it would work a little bit.

This marker has been in its current configuration for probably 10 years or so. I understand that the spring could have fatigued or taken a set, but I would think that it would work with a longer spring then. Additionally, I inspected the sear and it looks fine.

Does anyone have any thought?

Thank,
-D

Sear?

Check your sear

I thought that too, but the sear looks fine.

Tank input pressure?

Put a mec frame on it then trouble shoot. If its been 10 years then you reg pin assy orings might have gone Tango Uniform. If they are bad then chance are the rest of your oring will be or on the verge of going.

Your spring could be a contributing factor as well. 10 years is a long while but my money is on the valve pin.

Dont bandaid the problem, full rebuild including the ULT and lvl 10 is probably in order.

Quote:

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Originally Posted by SocialD

I tried removing a couple of shims from the ULT, but then it wouldn't fire. Replaced the shims and running away.

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Based on this, it probably isn't one of the orings in the regulator part of the valve. If one of the valve regulator orings was at fault, then removing the ULT shims wouldn't stop the air from leaking into the front chamber. This points to a problem at the front section of the valve.

Quote:

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Originally Posted by SocialD

I then tried a longer bolt spring because it seems like the bolt might not be resetting and then it wouldn't fire. I increased the valve pressure and it would work a little bit.

This marker has been in its current configuration for probably 10 years or so. I understand that the spring could have fatigued or taken a set, but I would think that it would work with a longer spring then. Additionally, I inspected the sear and it looks fine.

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The bolt spring does get weakened with use. Its only good for about 50000 cycles. It should be replaced after about 35000 cycles to guarantee that it will cycle and reset properly. I don't see this as a cause of the runaway issue, though. A worn spring usually only causes the gun to cough and take longer to reset.


How does the lip of the bolt look where the sear catches it? Is it nice and sharp, or is it rounded? Does the sear show any wear on the top side?

Also, is your rail bushing in place?

Quote:

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Originally Posted by xero28

Tank input pressure?

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It is preset about 600-650 psi

Quote:

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Originally Posted by Ando

Put a mec frame on it then trouble shoot. If its been 10 years then you reg pin assy orings might have gone Tango Uniform. If they are bad then chance are the rest of your oring will be or on the verge of going.

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I considered doing that, but I had to remove the sear pin from the sear in order for it to work with the HF. I'm not sure if I still have the sear pin or if I destroyed it removing it anyway.

Quote:

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Originally Posted by athomas

How does the lip of the bolt look where the sear catches it? Is it nice and sharp, or is it rounded? Does the sear show any wear on the top side?

Also, is your rail bushing in place?

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The sear has a very small radius on it. I'm guessing that it would be around .005"-.010". I didn't even think about the top of the sear. I'll take a closer look at that and the bolt.


Thanks to everyone for their help so far.

EDIT: I was able to go back through my old posts and I actually built the marker on 10/22/2003. So, it hasn't even been nine years yet.

Quote:

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Originally Posted by SocialD

It is preset about 600-650 psi

Your tank output is a little low but if that's been working for ya all these years...don't fix what's not broken

I considered doing that, but I had to remove the sear pin from the sear in order for it to work with the HF. I'm not sure if I still have the sear pin or if I destroyed it removing it anyway.
Hmmm...If you're talking about the sear "ARM" then yes putting a mech frame on is out of the question if you don't have another. You could always manually actuate it within the frame.


The sear has a very small radius on it. I'm guessing that it would be around .005"-.010". I didn't even think about the top of the sear. I'll take a closer look at that and the bolt.
If you have a decent camera take pics of the sear and bolt.

Thanks to everyone for their help so far.

EDIT: I was able to go back through my old posts and I actually built the marker on 10/22/2003. So, it hasn't even been nine years yet.
Even 8 year is a hell of a long time...good for you :cheers:

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Here are pictures of the bolt and sear:
http://i427.photobucket.com/albums/p...n/IMG_1353.jpg
http://i427.photobucket.com/albums/p...n/IMG_1352.jpg
http://i427.photobucket.com/albums/p...n/IMG_1351.jpg
http://i427.photobucket.com/albums/p...n/IMG_1350.jpg
http://i427.photobucket.com/albums/p...n/IMG_1349.jpg

They both look good to me.

Have you ck'ed your pin valve assy?

The sear and bolt do look fine.

Try a higher pressure tank. The higher pressure input might seal the orings better and prevent air from passing by.

I was able to get back to my marker tonight. I disassembled the entire valve, cleaned, lubed, and reassembled and with very limited testing (my daughter is sleeping upstairs) it seems to have corrected the problem. I'll post back tomorrow after further testing...when everyone is awake. Here's me keeping my fingers crossed.

I just tested the marker and everything seems to be okay again. Sorry that it was such a stupid problem, but now I know.

Thanks for all of your ideas, I really appreciated them.

-D

Sometimes a piece of dirt gets stuck in an oring and causes problems. Most of the time, a good cleaning is all that is needed in a mag, to get it going again.