ScupaPro Mk10+ IP creep

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First, my gratitude to couv, Zung, and halocline for all the invaluable information and fascinating comments over the years regarding my absolute favorite regulator combination, the Mk 5 and the 109/156. I still have my first Mk V (as we used to refer to them) and its 109 second stage. I've had them for more than 40 years, and have done all my own work on them since the 90s.

I have a second Mk 5 first stage that is more recent, with 5 lp ports and two of the larger diameter hp ports. I bought it a few years ago, almost unused in virtually new condition, clean as a whistle inside. I installed new o rings, a washer or two and the filter although everything seemed fine, though the o rings were a bit dry. IP locks at 135-137, no extra shims, solid as a rock. I've semi-retired my two port original mk 5, even though I replaced the light yoke long ago. I still use my 40 year old 109, upgraded to current standards with an s poppet, matching longer balance chamber, more recent lever and an appropriate adjustment spring. The chrome finish is still beautiful, almost flawless, despite many hundreds of dives and numerous plane trips carefully packed in my carry-on. All rubber parts have been replaced several times, of course.

I use the combination of the newer Mk5 and the updated 109/156(almost a 250V) on my tropical dive trips. They outperform most anything else, especially with the 109 tuned to utter perfection, and the impact they have on other divers and boat crews is interesting and amusing in the extreme. Compared to what's out there, they also are in another and much higher aesthetic category. "A thing of beauty is a joy forever."

I'm curious, halocline, about the Mk 5 brass turret retainer you mention. I think old Scubapro spec sheets call it a swivel retainer. Both my Mk 5s have brass retainers. I know about the overtorquing issue, and it's not a problem for me, since I (very carefully) do my own work. Still, I wonder if the stainless steel retainer is available as a new part, if it would fit properly, and if it it's worth doing a replacement the next time I service them, all things considered.

Many many thanks for the generosity, the expertise, and the sea of humor which obviously floats all of your boats.
 
I'm curious, halocline, about the Mk 5 brass turret retainer you mention. I think old Scubapro spec sheets call it a swivel retainer. Both my Mk 5s have brass retainers. I know about the overtorquing issue, and it's not a problem for me, since I (very carefully) do my own work. Still, I wonder if the stainless steel retainer is available as a new part, if it would fit properly, and if it it's worth doing a replacement the next time I service them, all things considered.

If you're sure the swivel retainer has not been severely overtorqued, and you are the one doing the servicing, there's no immediate reason to replace it. A small of group went in on a run of reproduction SS retainers; Zung arranged that in Europe. I'm sure there are some of those available. I sent at least one to Bryan at vintage doublehose, so you could buy it there. Scubapro no longer has any.

I know at least one of my MK5s still has a brass retainer, next time I rebuild I'll replace it, but I'm not in any hurry. I ordered some mostly to support the effort.

The 109 upgraded and tuned well is a pretty jamming 2nd stage, no doubt about it. Probably about the most successful 2nd stage in history if you consider longevity, aesthetics from a design simplicity and elegance perspective, dive performance, and influence on subsequent regulators.
 
I only kept 1 of those special order retainers for myself, because I only had 1 MK5 at that time. But due to the extreme bad influence of this board, I've got quite a handful now, and still only 1 ss retainer. :)

But since I also have a torque wrench I calibrated myself against the highly mission-critical scales of 2 local supermarkets, I don't loose any sleep over that one.
 
I thought I had 5, but I only found 2 the other day going through some stuff. I didn't think I had installed any yet, and I thought I only sent one to Bryan. So I guess I'm unofficially missing 2 of them.....
 
Brian tells me he had two, used both. Any other possible source? if any are available for sale or for installation, an email would be quickly answered. I'd like to have one to use on the late model Mk 5 that sees a lot of use. I suppose another production run is not likely.
 
I think those turret retainers were made from ether. I cannot recall how many we ordered; we don't remember using any-no one has any left. But a huge amount of effort (thanks Zung) went into procuring a run. :confused:
 
I can only imagine the technical difficulties involved with machining substances ethereal.
 
You're in the Catskills. How far from Syracuse? Send your MK10+ to National Aquatic Service in Syracuse. Mike, the owner, at least used to dive only the MK10+, internally retrofitted to an MK10. He'll take care of you.

No one has mentioned the spring as a possible culprit. Certainly the piston and seat are the first places you want to look. If that doesn't work, shouldn't the spring be considered? An old spring, long sitting inside an MK10+ from the 1990s, might need to be replaced.
 
I've never seen a mainspring cause a problem in a balanced piston 1st stage. It certainly wouldn't cause creep. I've had a few MK5s with low IP, like 120 with the shortest seat and no shims, I switched the spring, little effect. Someone sent me a NOS spring for a MK15, tried it at the next rebuild, no effect. These springs are pretty beefy and they're relaxed when the reg is not pressurized, so they last a really long time. I've read that sometimes they can stiffen up over time, resulting in high or drifting IP, but I've never personally experienced that. Drifting means they lock up at a slightly different IP every time you cycle them, and is not creep where the IP rises when the reg is closed.

There was an issue with mainsprings in some old US Divers doublehose regs; one of the vintage fans (maybe herman?) found some new springs that worked well. With those, the IP would drift down, usually you'd want to set it pretty high and it would hold for a while, but after a couple of dives it would be back down to under 125. I guess the springs were losing strength and causing IP to drop, which is more intuitive to me than a bad spring causing high IP.

This is a really simply problem, either the seat is bad or the piston edge (much more likely IMO) is bad.
 
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