ScubaPro MK10 leaking air

[rhwestfall]

The philosophy I learned under and abide to (right or wrong is one's choice) is that a "pony" in an alternate air source, no different than an octo off your tank - always ready. It is there for immediate use at any given period of time, so turned on and fully operational.

A DECO cylinder is there for a specific use, and is maintained charged and off to protect the regulator. You only are going on it at a specific time, and there is a procedure to utilize it. Much different than an alternate air source.

YMMV.

 

[Cdncoldwater]

Can anyone else confirm this one?

Pretty sure it was covered on my ScubaPro Tech course....

 

[p_kos]

Can anyone else confirm this one?

I don’t think so. Unless it’s an Atomic regulator where the second stage low-pressure seat/orifice is in the open position when not pressurized I can’t see how an unpressurized reg would get water up to the 1st stage while probably mounted on a cylinder (tightly screwed in DIN reg, yoke is not a great choice on slung bottles but if tightly screwed on should also keep water out). Can’t see how water could get in through the seat retainer cap hole either if the cap and the crush ring/oring below is in place properly and seat is intact. As for water getting past the piston, if the oring there can normally keep 3000+ psi of gas from leaking out then I doubt water can sneak past it going the other way. I personally charge slung bottles and turn off but keeping a slung pony/bail out charged and on makes sense as well.

 

[halocline]

Regarding the leak, it is almost certainly the seal or o-ring that is seated on the shoulder of the HP chamber before installing the HP seat retainer. Earlier MK10s used a 013 o-ring for that, probably a 85 duro, but later kits replaced the o-ring, which was finicky to seat properly, with a more idiot-proof crush seal that has a square profile and fits nice and snug on that shoulder. So you could fix it by taking off the seat retainer (don't disturb the seat itself, just leave it pressed in the retainer) and then replace whatever is in there with a 013 90 duro EPDM or viton o-ring. You can find a socket (from a socket wrench set) that is the approximate size (a bit smaller) of the o-ring and use the socket to push the o-ring in place with a bit of firmness. A wooden or plastic dowel the right diameter would work fine as well. I have a socket that I use for it, but I can't remember what size it is.

Then you can re-install the seat retainer and your leak will be gone. It's not a cracked seat, (although you can look at it while it's out) and MK10s never had a straight shaft piston with no shoulder. Early MK5s did, maybe that's where the confusion was. There might be a small amount of IP creep after because the seat/piston might not exactly line up. I wouldn't worry about it, MK10s usually have a small amount of creep until the seat breaks in, IME.

Regarding flooding your regulator by keeping the valve off, the only way the 1st stage would get water intrusion would be if there was a serious leak, or the 2nd stage purge was depressed while the reg was un-pressurized. Otherwise the 2nd stage seat would seal off water getting into the 1st stage, at least theoretically. It is an 'upstream' valve at that point because the water would be traveling from the 2nd stage to the 1st stage, so presumably the increased pressure in the 2nd stage body (from depth) would not push the 2nd stage valve open. But if you bump the purge, you are mechanically opening the valve, and then water would be free to travel up the hose into the 1st stage, and also into your SPG.

 

[Jim Lapenta]

Stage and pony bottles should always be kept charged**. It doesn't take much for water to get past the o-ring if you don't. As others have said if the stage gets bumped or turned while unpressurized it can leak. Even DIN connections rely on pressure to create the seal to some degree. Especially if the o-ring is a little worn or compressed.
I've seen it numerous times on regs I've gotten in for service.
My own practice and the way I teach and was taught with a slung pony is to charge the reg and turn it off on the surface. Then crack the valve again at the bubble check/S-drill stop. Once I reach my target depth I crack it again to make sure I haven't bumped it on the way down. At the turn point of the dive it gets cracked again. Then when I reach the upline. I also usually do a short stop at 30ft if I'm doing something deeper than 60 and not on a planned deco dive. Here I open it and leave it open. Every dive outing if I'm carrying a pony I'll do the safety stop on it. Helps to build muscle memory and ensure the reg is working.
** With stage bottles it also depends on whether it's getting carried or dropped. Dropped stages like those used in cave diving should be kept charged if possible but not always practical to keep checking the valve because you don't have it with you. Which is why some turret regs are not recommended for stage use because of the chance of them becoming unpressurized. If this happens water can leak into the 1st stage through the turret.
They will still work usually if this happens and you'll get a couple of wet breaths, but you'll also force water into the SPG when it's turned on.

 

[shurite7]

It's not a cracked seat, (although you can look at it while it's out) and MK10s never had a straight shaft piston with no shoulder. Early MK5s did, maybe that's where the confusion was.

This is right, I stand corrected, the Mk10 piston never had the straight shaft, the Mk5 did. It is plausible, but extremely unlikely the HP seat is cracked. The red o-ring is what comes to mind in this case. Nevertheless, I still advocate taking the reg back to the LDS that serviced it and have them fix the issue.

 

[HKGuns]

Took the cover off and look what I found. Indeed red and indeed bunged up. Thanks for all the help.

 

[p_kos]

Took the cover off and look what I found. Indeed red and indeed bunged up. Thanks for all the help.

View attachment 656396

Wow! I would show that to the shop where it was serviced, that is not a natural occurence. They owe you an apology and should fix it for free. And to think the red crush ring was supposed to be more foolproof!

 

[Centrals]

.......why people recommend soaking a regulator pressurized on a tank when cleaning.

Need no further explanation.
Cheers.

 

[Ghost95]

Now my question is...could leaving the regulator unpressurized at depth cause that o-ring to be extruded to that space? Usually that seal would have pressure pushing out on it to keep it sealed. Just curious.

Glad you found the problem.