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Thread: RT Classic - Leaking through the velocity hole and erratic velocity

  1. #1
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    RT Classic - Leaking through the velocity hole and erratic velocity

    Hey guys,

    As some of you may know I have been having some issues getting the LX tuned to where it won't leak on my RT Classic...

    Along the way I have run into some other issues that need to be resolved before I try again on the LX...

    Took the gun to the field for the first time Sunday and played a game with it... and by the end of that game I was leaking out of the velocity hole...

    Prior to the game it chono'd decent (275-290ish - 800 PSI input)... I switched guns and kept playing. Throughout the day I aired up the RT Classic several times and it was NOT leaking (this was without firing it though).

    At the end of the day I went to the chrono with about 50-75 rounds and shot rapid fire and somewhat slow over the chrono to see if the leak would come back and how consistent it was in terms of velocity. The leak did come back after maybe 20-30 shots... and every once in a while I would have a 100 FPS drop in velocity for a single shot (I would be shooting 275-290 and then a super low velocity shot would happen where it would be 180-190 for a single shot... then go back to 275-290).

    At that point the only thing that had not been changed were the o-rings and washer thingy on the reg pin assembly. I changed them out.

    I realize this is an RT Pro valve-image but I couldn't find an image of an RT Classic valve and they are similar enough for my purposes:

    Name:  RTPX-Valve w Level 10_zpsxqjginj5.jpg
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Size:  25.3 KB

    So far I have changed out the following with fresh o rings from a new AGD parts kit or new parts from AGD:
    -Power tube tip o ring
    -Power tube o ring (below spacer)
    -bumper
    -# 16 (no #15 in rt classic valve)
    -# 19
    -# 20
    -# 11
    -# 9
    -# 7
    -# 2
    -New high pressure piston
    -New sear
    -Both O rings and washer thing on reg pin assembly

    Did NOT change springs in the back of valve.

    Up until this evening the only soft seals that had not been changed were the 2 orings and the washer sandwiched between them on the reg pin assembly. When I pulled out the reg pin this is what I found in between the 2 orings on it:



    As you can see... there was a gap in this one that you can see at about the 10 o'clock position.

    I also own an RT pro... and have a parts kit for that... I noticed in the RT pro parts kit the part matched exactly... when I compared them they were the same size and both had the gap.

    But when I looked in the RT Classic parts kit it had a part in there that was the exact same size but with NO gap... it was one piece. So... I suspected somewhere along the way someone replaced it with the part from an RT pro because that was all they had on hand... no way for me to know. I used the part out of the RT Classic parts kit (no gap).

    I oiled the o rings on the reg pin assembly and added air into the male quick disconnect and aired back up and fired about 20-30 shots and it started leaking out of the velocity hole again. It also sounded like I was still getting those low velocity shots every once in a while (no chrono, could only go by sound).

    Any input on whether I should try the washer with the gap from the RT Pro kit? could that be the issue?

    Should I try going back to the old piston? It didn't leak...

    These are the two things I am curious about...

    Let me know if there is anything else I should consider to address this leak.

    Thanks for reading this whole thing, and for your help and knowledge.

    Have a good evening and a good week.

    M
    Last edited by Mondoatx; 02-28-2017 at 12:01 AM.

  2. #2
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    the gap is there on all of mine, it's the only way to remove it so you can change the o rings. how did the springs on the pin look? take the reg pin out of the Pro and put it in the classic and see if it still leaks. while you have it out check the visually check the 2 pins and see if they look the same. the spring pack on the classic could be weak and letting the air vent. we ran into this at Tuna ball a couple of years ago. i have also had problems with the reg pin leaking and after 3 or 4 cleanings it would finally seal.

  3. #3
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    That ring is just for spacing between the o-rings, I don't think it matters if it is split or not, but I haven't noticed one that was solid.

    I can't remember (about the leak), are you using the gold spring and did you replace your reg piston? You might be able to lower your velocity to top out at 275 and stop the leak if it is over-pressure from the level 10. It should stop leaking at some point as you lower the velocity, if it is over-pressure. It's a temporary fix and good test.

    If you have replaced your seals and lubed them, the main source of low velocity at easy firing rates may just be roll outs. Is your detent good for your paint? If not are you pointing upward at the chrono (not a common practice).

  4. #4
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    Spider,

    While I was trying to install the L10 I discovered some other problems... so this last post/issue with with all level7 stuff in it (with a high pressure piston I recently installed because I read it was needed for L10).

    So... I was leaking through the velocity hole after 20-30 shots... and I knew it was either the piston or the reg pin springs (process of elimination)... and I put the old piston back in (the one that came with the gun and was being used with the L7 setup)... and the leak went away .

    I am shooting here in the garage... and there is no leak (probably 100 shots... usually I would start leaking out of the velocity hole within 20-30 shots)... but I don't have a chrono here... so I won't really know until I throw some paint over the chrono this wknd.

    Could the high pressure piston I got be defective? Do they take time to break in? Should I try changing the O ring on it? Maybe swap it with the ring on the old one?

    The gun is not dry... it is well oiled... so not sure what is going on... but when I replaced that new piston with the old one the leak out of the velocity hole went away... so it seems to me that was the problem.

    Now the question is... if the high pressure piston I got is leaking... what do I use when I go to try the level 10 again?

    Oh... the barrel is a .691 bore... so it is large... and I noticed a couple of times it double fed last weekend... but when I was getting the super-low velocity shots (180-190) it was a single ball...

    The nubbin is brand new (on of the new style plastic ones).

    I am pretty tall and was def not shooting angled up at the chrono... my height doesn't allow that.

    Thanks everyone.

    Quote Originally Posted by Spider-TW View Post
    That ring is just for spacing between the o-rings, I don't think it matters if it is split or not, but I haven't noticed one that was solid.

    I can't remember (about the leak), are you using the gold spring and did you replace your reg piston? You might be able to lower your velocity to top out at 275 and stop the leak if it is over-pressure from the level 10. It should stop leaking at some point as you lower the velocity, if it is over-pressure. It's a temporary fix and good test.

    If you have replaced your seals and lubed them, the main source of low velocity at easy firing rates may just be roll outs. Is your detent good for your paint? If not are you pointing upward at the chrono (not a common practice).

  5. #5
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    Just to be clear. When you say velocity hole, are you talking about the hole on the side of the valve, or the allen key hole in the back?

  6. #6
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    Quote Originally Posted by Laku View Post
    Just to be clear. When you say velocity hole, are you talking about the hole on the side of the valve, or the allen key hole in the back?
    Exactly. Side hole leak (or side AND back hole leak) could be a bad oring on piston OD. From the testing you've done, at this point, a back hole leak ONLY is a bad piston; return to vendor for replacement.
    Last of the Salzburg Clan

  7. #7
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    Hey guys,

    When I said velocity hole... I meant the hole the allen key goes in to adjust velocity...

    I ended up going back to the old piston (the one that came with the gun when it was setup on L7)... and the leak went away.

    I played with the gun Saturday for a few games (before I bailed... it was super rainey)... and no leaks... it also chrono'd very consistently (277, 276, 274) so it seems the gun is fundamentally sound...

    So... you guys think I should take ask AGD to take back the piston they sent me?

    I am going to try it one more time to be sure... but I was running 1100 lbs saturday with no problem on the old piston... that HP piston was struggling and leaking with just 800 lbs... and would totally freak out with 1100...

    Thanks guys.

    Oh, one more question... when I try to install the level 10 again... should I do so with 800 lbs of pressure... or 1100 lbs? I intend on running the gun with 1100 lbs regularly (I know I know... I should just shave down the on off pin)... just not sure if that will impact tuning/install of L10.

    Thanks again.

    M

  8. #8
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    Quote Originally Posted by Mondoatx View Post
    Oh, one more question... when I try to install the level 10 again... should I do so with 800 lbs of pressure... or 1100 lbs? I intend on running the gun with 1100 lbs regularly (I know I know... I should just shave down the on off pin)... just not sure if that will impact tuning/install of L10.
    I would test and trouble shoot at 800, then step up the pressure afterwards. You want clean sear engagement and on/off function, which is easier to check with single shots.

    If the reg is good, it shouldn't have a problem. The inlet pressure should only get to the on/off and reg pin. You would like to get the rest sorted out before finding high pressure difficulties in those particular areas.

  9. #9
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    I may have missed it in reading. BUT was the leak still there after replacing the 2 Orings and plastic spacer on item 12 regulator pin? If so then I'd change the Oring on the piston for one last check. If the leak is still there then yes I'd say there is some sort of issue with the regulator and get it replaced.

    As far as tank pressure for testing. A normal operating pressure tank is always best for trouble shooting. Higher pressures will just amplify any potential issue that could be there.

  10. #10
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    Black Death,

    Yes, the leak was still there after replacing the 2 o rings and spacer on the reg pin. I will try changing the o ring on the new piston and give it another go.

    And duly noted to you and spider... set up LX with 800 lbs.

    Thanks guys!

    Quote Originally Posted by blackdeath1k View Post
    I may have missed it in reading. BUT was the leak still there after replacing the 2 Orings and plastic spacer on item 12 regulator pin? If so then I'd change the Oring on the piston for one last check. If the leak is still there then yes I'd say there is some sort of issue with the regulator and get it replaced.

    As far as tank pressure for testing. A normal operating pressure tank is always best for trouble shooting. Higher pressures will just amplify any potential issue that could be there.

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