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#181
Riddle of the Leaky Reg
JeffWilsonMT - 8/04/2013 8:17 PM
Category: Equipment
Replies: 16

Hey all - I have a weird one that I wanted to run by all the experts out there that might have seen this situation with a reg previously before I go to the shop and have someone tear the thing apart and slow me down from diving more!

I’ll give you the facts, and I’ve even got a little clip I took of the reg leaking on a tank so that you can see exactly what I’m talking about. http://youtu.be/rU0lR3aMG-0
  • I have a brand new Cressi MC-9 yoke reg (20 dives) and it’s starting to leak right near where the O-ring and the first stage meet.
  • It doesn’t seem to leak when the tank is full, as near as I can tell (steel 100, 3400psi). I left my SPG plugged in for an extended period of time and didn’t have ANY palpable change in pressure reading. However, it may just be that small of a leak.
  • There is visible and audible bubbling AFTER a dive that is akin to one stream of champagne bubbles (very small).
  • The equipment is cold, and wet which enables identification of the leak.
  • I reproduced the leak with 3 other independent tanks, all after dives (and theoretically [1000psi).
  • I replaced the O-ring in my tank, and it persists.
  • Here’s the weird one: took it into a shop and watched them throw it on the bench test, and there is no bubble whatsoever. I made them double check it and saw it myself.
  • I discovered it in a post-dive inspection, but dove it twice more after that and haven’t had any problem, except that it leaks...
So any idea what could be causing the leak, given all those facts?

Thanks to any smart detectives out there that can piece this one together.

-Jeff
#51831
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Greg - 8/04/2013 8:35 PM
Seems like you need to replace the oring on the tank valve. Get a new oring and lube it up with some silicon before putting it in. There is nothing mechanical going on at that connection. Just the first stage connected to the tank valve. And the oring is the only thing that makes it an air tight seal.
#181
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JeffWilsonMT - 8/04/2013 8:41 PM
Thought so too! But as I said, I tried it on three tanks and saw the same thing, and then replaced my own O ring, making sure to use silicone lube as well, and the video attached is the dive after I did that! Wish it were that easy.
#3240
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daz88 - 8/04/2013 8:47 PM
you’re not going to see the pressure change much coz, yes....it’s that small of a leak.Just look at the sealing surface on your reg. and on your tank. if you have a little "nic" it could coz a bad seal. other than that...o-ring. When I’m traveling I think about half the tanks I end up with are leaking at the O-rings, you kind of get used to it. at home I have my own tanks with a DIN setup, so no worries.
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Greg - 8/05/2013 12:25 PM
From daz88: Just look at the sealing surface on your reg. and on your tank. if you have a little "nic" it could coz a bad seal.
I agree with daz88, besides the o-ring, which it still could be...if you’re 1st stage is chipped or nicked where it connects to the tank valve, you’ll never get a good seal.
#2638
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John_giu - 8/05/2013 2:25 PM
IMHO,

I would contact Cressi and have them warranty the REG. Most regs today have a life time warranty as long as you have done the annual maintenance.

You should NEVER have to go more then hand tight on the saddle vavle.
#5471
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DiveBuddyChgo - 8/06/2013 4:59 AM
When brass gets cold it shrinks. That’s when your leak starts. I would would 1st check the yoke nut retainer face for any kind of scratch/damage. Next I would remove the yoke nut retainer, replace that oring against the body. Reattach the yoke nut with the new oring and tighten to the proper torque setting. I have seen divers strip out the treading of the 1st stage brass housing. Find a dive shop that employs a full time life support tecnition. Have done what I said and your problem is resolved. If that doesn’t do the trick. Then replace the yoke nut retainer because the face is damage/warped that you can’t see. Also don’t use grease on the tank o ring. It’ll collect dirt and you’ll then have two leaks
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Greg - 8/06/2013 6:56 AM
From DiveBuddyChgo: Also don’t use grease on the tank o ring. It’ll collect dirt and you’ll then have two leaks
I have never thought of it that way. I’ve always put a little silicone on those orings. But your answer makes sense.
#1200
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Dutch - 8/15/2013 3:06 PM
Some regs have a broader orifice wall where the reg meets the tank o-ring. With the advent of smaller o-rings, there began to be some problems. Then the DIN/yoke combi tank valves started showing up. The tolerance on those and the first stage is even less sometimes. It seems like the reg is seating on the oring but the insert is just too wide and does not allow for the proper seating. I started carrying my own insert that worked with my reg, after I modified it. I changed the fitting to a DIN as I am diving outside of the US these days and DIN is the standard.
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DiveBuddyChgo - 8/16/2013 3:27 AM
One more suggestion. If you are using a vitron or nylon tank oring. Replace with the normal cheaper black oring. It is softer and may just stop that leak. Remember to let us know what the problem was when your leak problem gets resolved.
#181
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JeffWilsonMT - 8/20/2013 10:06 AM
Will do!
#181
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JeffWilsonMT - 9/12/2013 9:33 PM
So it seemed at first that daz88 was on the right track - upon closer inspection, there was a very small nick in the surface where it meets the oring. You can see the brass coming through where the galvanized finish got chipped off somehow.


Took DiveBuddyChgo’s suggestion of switching out to the black O-ring. Also, did some research to find that silicone grease is a DEFINITE no-no for tank O-rings, especially if you’re putting EANx in there, because it is flammable I guess.



That all seemed to fix it for a while.... Until just recently when the problem re-emerged! I probably did 12 dives in the interim, and only just now failed the buddy bubble check. I had a moment, so I changed O-rings again. Still a little bubbles. Did the dive anyway, no problem, but still a little stream at the safety stop.



One other interesting thing is that I turned the regulator over, just to check that it would spit bubbles out the /opposite/ side, and it didn’t! Same spot on valve.



That leads me to think (as I saw a little when I was changing the O-ring) that there are possibly some dried salt crystals in there behind the oring allowing it to leak out. Not a problem of the reg anymore at all! The old problem was replicable on other tanks, but I haven’t tried my reg on another since it re-occurred.



Doesn’t seem to be dangerous, so I’m going to keep an eye on it and see what ultimately fixes it. The faber blue steel valves seem kinda cheap and not very "meaty".
#1200
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Dutch - 9/13/2013 1:56 AM
Like I said, it is probably the valve size/reg seat situation. Go to a dive shop that has one of these things in stock, http://www.amazon.co.uk/Dive-Cylinder-Valve-Convert-A-Clamp/dp/B005QLXOFQ , try seating your reg against the oring and look closely to see if the lip of the converter actually clears your reg seat. If not, try to find one that does. When you find one, buy it. After that, dive only with DIN tanks and use your own insert.
#181
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JeffWilsonMT - 9/13/2013 7:20 AM
Yeah, no doubt I have wished I had a DIN.
#1200
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Dutch - 9/13/2013 7:41 AM
you can convert
#3240
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daz88 - 9/19/2013 1:54 AM
next time you get a new reg go DIN. If it’s little slow bubbles.....no worries since you know what it is. Most of the time when I travel and using the resort tanks, there is a small stream of bubbles at least half of the time. It’s bearling anything and doesn’t shorten your dive at all. if they have them, I try and find tanks with the pro valves and take out the plug, if not....screw on my yoke converter and listen to the bubbles from behind my head. ;) it’s all good.....better than the sounds of being at work. : )
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DiveBuddyChgo - 9/19/2013 5:58 PM
That little chip of chrome missing is what is causing the leak. That universal yoke retainer is no longer any good. What you can try is to file of the chrome with a flat fine file. The brass underneath is very soft. File it flat. If it doesn’t work then you’ll have to replace that part anyways. Try it cause its not going to hurt that part anymore. Just take enough chrome of so that its flat across. That part should retail for about $16. If you want to change out to DIN its about $60 parts. If you do this yourself don’t tourqe more then 30NM on a brass housing. You can double thread the 1st stage very easy also. So be very careful. Thanks for keeping us all informed.