Scubapro MK2 leaking yoke retainer

[Couv]

Yes, if we got the chart right that should be a -015 Make it a 85-90 duro if you can as there is a high pressure differential in that application.

In the attached file you may see a spacer that goes between the yoke and body-not all MK2s have this spacer, especially the older ones. I don't have any other MK2 files to post. Even it it is missing, it probably would not be the cause of the leak.

 

[BenjaminF]

Thank you! I think that I need to start being more discriminating when I accept strange regs, if only so that I have some sort of "standardised" collection

---------- Post added August 13th, 2013 at 12:33 PM ----------

Just checking.......are you sure it's not the tank o ring?

Checked with a different tank, after making sure that the o-ring on the tank is ok. Still leaks. Now sourcing an -015 and will try with that.

---------- Post added August 14th, 2013 at 10:10 AM ----------

OK. So the o-ring was replaced, but the leak stayed. Then somebody else (with loads more experience than me) walked past, listened to the noise and said that the piston should be checked. After cleaning out some accumulated gunk and swapping the o-ring there, the leak vanished! So it seems that the hard parts are all ok and the regulator should work (I hope).
So now all I need to do is obtain a service kit and clean/rebuild the regulator before diving it.

Thank you to everybody for their help, and especially to couv for the annotated diagram!

 

[Couv]

Benjamin,

If you change out the 2 piston o-rings (-008 & -022) and the leak stops; check the IP. If it's steady then the seat is probably ok.

 

[BenjaminF]

They were changed, and the IP is steady.
I just want to open it up and clean it out (not all the accumulated gunk could be taken out at the time) before diving it.

 

[halocline]

The service kit consists of the two piston o-rings, the seat, and maybe a filter. It makes no sense to open up the reg and clean it without replacing those parts unless you're sure they were replaced recently.

Unfortunately the price for the SP 'kit' for this reg is particularly insanely priced considering what it is. If you just replaced the o-rings and you're confident they're okay (EPDM or viton or nitrile duro 70) then you should find a seat and replace that too. It's just a small plug of teflon or some similar plastic; you could probably get a perfectly good aftermarket one from the trident catalog. Then clean the cone filter carefully and you'll have a rebuilt regulator that will work well for years.

 

[BenjaminF]

:O I think that I need a shot of adrenalin to the heart or something. Given the price of that kit, I would expect the filter to be made of solid gold.

I'm going to be looking for a new seat then. There is a place which sells from the Trident catalog not too far from where I live. It's got to be less painful that the amount which the shop wants for the service kit (a punch in the face would be less painful too).

 

[redacted]

So the original leak saw coming from the ambient chamber rather than the yoke connection?

 

[BenjaminF]

So the original leak saw coming from the ambient chamber rather than the yoke connection?

Yes, it was.

 

[redacted]

Yes, it was.

I really is important to accurately determine the source of a leak in order to properly troubleshoot it.

 

[halocline]

I really is important to accurately determine the source of a leak in order to properly troubleshoot it.

Yes indeed. I'm trying to picture how you could have a leak from the ambient chamber in a MK2 and have steady IP at the same time. I don't see how....the piston stem o-ring is not subject to HP air, in fact the only o-rings that are, are the yoke retainer and the HP port plug o-ring. The seat would have to be leaking for any HP air to escape otherwise, and then you'd have IP creep. Either of the piston o-rings leaking would be IP air to ambient, which would mean IP dropping until the reg 'burped' back to IP.

So something's not right. Easiest/best thing is to simply rebuild; you're most of the way there already. This is the real beauty of the MK2; utter simplicity. No dynamic o-rings subject to HP air, only one way out for that air, and a nice teflon plug of a seat at the HP orifice, which insulates the piston shaft from the rapidly expanding air. This is why these regs are more freeze resistant than the MK25.