ScupaPro Mk10+ IP creep

[oncor23]

Okay...I believe I know the answer to this one...but this is a discussion forum, so here goes:

Had my Mk10+ serviced recently...in April. Noticed at the end of a dive when I did some practice switching between my 2nd stage and the octo, that freeflow was an issue. I was in shallow water...maybe 4 ft deep at the time. Thought it was my fault as the mouthpieces were pointed up, but never had to be all that careful before. I had to turn up the adjustment on the R109 to stop the freeflow. So, I had one of those cheap, small IP gage's and decided to check things out. Here's what I got:

Tank: 2800 psi
IP gage hooked into the quick connect to the BC hose
2nd stages: R109 converted to a balanced adjustable; R190 octo
IP gage when I cycle the purge: drops 20 psi and returns to 128....then creeps to 158 before stopping. I did not have the second stages underwater to see if they are leaking air. Maybe the second stages are leaking when pressure hits 158.

The question: The Mk10+ needs to go back in the shop for a checkup. The tech at the shop thought I could dive it once more before going in. I'm not so sure. Maybe I'd better dive my backup Mk 2 and just send the Mk 10+ straight in for service. Bad seat? Bad o-ring. Bad orifice? Bad knife edge?

Yeah...ScubaPro...too bad I can't edit the title...oh wait, I can edit in advanced mode!

 

[Fishpie]

Since you have a back-up you might as dive that, but you'd probably have no problem with the 10+.
The plus has a dull piston end and the same seat as the 20 and 25....problem is probably o ring related, corrosion where the big o ring seats or too slick piston shaft......does it bubble from the ambient holes?
Fine emery cloth the piston shaft can work wonders.

 

[Couv]

You are probably correct about the IP causing the freeflow. The second stage is acting as a relief valve.

Safe to dive? Probably, but if you have a backup reg may as well not. First off, the i.p. is way too high and the creep is unacceptable, so another shop visit is in order. Taking it back to the same shop that returned it to you this way, and advised you to dive it again, may be an error-unless you've had excellent service from them in the past and consider this a one off.

Both you and Fishpie have hit on a few possibilities, but unless you're willing to DIY about the only thing you can do at this point other than taking it in for service is:
A) Let it sit overnight pressured if no help go to B
B) Cycle it 30 or so times. Air on/air off purge = 1 cycle
To save air, disconnect an plug all hoses and ports except one second stage. After you've cycled it 30+ times check it again.

Keep us posted.

 

[Zung]

I wouldn't dive that MK10+; I'd take it back.

If you're lucky, it's the seat: a brand new seat can develop a creep, because of some surface imperfections probably; I had a case like that with a brand new seat, and an easy fix: just replace the seat. Especially the 1st generation white seats are pretty bad; the current dark grey ones are very good.

If you're unlucky, it's the piston. I reported a pretty bad case here. The edge of the piston can be scratched by some careless handling or, less likely, some debris that got inside. That requires a replacement of the piston if you're well off, or some polishing if you have a steady hand. And the 1st generation pistons are made of brass that scratches very easily: if you have it, the one with the yellowish stem, replace it anyway.

 

[oncor23]

I wouldn't dive that MK10+; I'd take it back.

If you're lucky, it's the seat: a brand new seat can develop a creep, because of some surface imperfections probably; I had a case like that with a brand new seat, and an easy fix: just replace the seat. Especially the 1st generation white seats are pretty bad; the current dark grey ones are very good.

If you're unlucky, it's the piston. I reported a pretty bad case here. The edge of the piston can be scratched by some careless handling or, less likely, some debris that got inside. That requires a replacement of the piston if you're well off, or some polishing if you have a steady hand. And the 1st generation pistons are made of brass that scratches very easily: if you have it, the one with the yellowish stem, replace it anyway.

I believe the original piston was replaced in a prior service, shortly after I got it. I'm not the original owner...I have no idea how much use the regulator had before I bought it. I suppose it could still be a brass piston, but probably not. I read your long thread about your Mk10 Plus #3. I don't believe my Mk 10+ had a serious issue with IP creep before the last service. I hope it's just a bad seat. I hope it's not sloppy handling and a damaged piston. I don't plan to take it apart and try to "micro-mesh" the piston edge back to health. If the shop tells me that the piston has gone bad...and I have to pay for a new one...it may be time for me to switch to another, less convenient shop. I haven't gone into all the details of my conversations with regard to this issue, but it would be safe to assume I'm not real happy. I've done maybe 5 dives since getting it serviced in April...all fresh water and not in conditions likely to leave large particles inside the regulator, thus causing damage since the service. One could well ask how it passed inspection?

---------- Post added ----------

I checked the old piston that came out of the Mk 10+ on a service about 2 yrs ago. That was steel, so I imagine the current piston should be steel. I can't believe the seating surface is already in this bad a shape. What about the orifice? Could that have somehow been damaged and causing the creep or does it have to be the HP seat or the piston seating surface?

Also, my balanced adjustable will free flow if I push the purge button and there is no counteracting pressure like holding it underwater facing down. Maybe when I tried it the IP pressure was above 140...but it free flowed. I tried turning the adjustment all the way in...still free flowing. Never did that before.

 

[Zung]

I believe the original piston was replaced in a prior service, shortly after I got it...

Any idea why they did it in the first place?

...One could well ask how it passed inspection?...

There wasn't one for sure

... I checked the old piston that came out of the Mk 10+ on a service about 2 yrs ago. That was steel, so I imagine the current piston should be steel. I can't believe the seating surface is already in this bad a shape...

It takes only 1 bad service to mess things up. It was reported on another board that the creep had gone away after the tech stopped ultrasonic'ing the pistons. My view is that the edge might hit other metal parts in the tray. Or, more conviniently, the piston got dropped.

... What about the orifice? Could that have somehow been damaged and causing the creep or does it have to be the HP seat or the piston seating surface?...

No. The only way to develop a creep in the sealing between the piston and the seat: if it's not perfect, air leaks pass the seal into the IP chamber, raising the IP and pressing back again the piston/seal until it seals again... or not.

... Also, my balanced adjustable will free flow if I push the purge button and there is no counteracting pressure like holding it underwater facing down. Maybe when I tried it the IP pressure was above 140...but it free flowed. I tried turning the adjustment all the way in...still free flowing. Never did that before.

That's not good; don't dive it, take it back for a refund and look for another shop. But it can still be the seat.

 

[halocline]

Depending on how long it takes to get from 128 to 158, I wouldn't dive it either. If its an hour, fine, dive it, but a few seconds (anything under a minute, I suppose) and that's very serious. As Zung correctly mentioned, the only thing that causes this is either a problem at the piston edge or the seat.

Mk10+ pistons can be notorious creepers, although the current seat (same as MK20/25) is really good. And if the shop you brought it to is a SP dealer, they'd have used a new seat, so my guess is there's a problem with the piston. Take it back, see what they say. They'll probably tell you it needs a new piston, at which point they'll say there are no new pistons available (I don't know if that's true or not) and then point to a nice shiny MK25. If you politely remind them that the problem didn't exist until they serviced it, it would be interesting to see what creative response they have to that.

As a last resort, I'm looking for a MK10+ to play with, so I'd be fine with trading you a MK10 (not plus) for yours provided the piston is not totally trashed. I'm perfectly comfortable resurfacing the piston edges. The difference is the MK10 has a knife edge piston and different seat that is less prone to creep. I have several of those. I could also try fixing your MK10+ for you, but I'm not a certified tech (like the guys in the shop, hehe) so you'd be taking your life into your hands.

I'm interested in knowing if there are generations of the MK10+ piston as there were for the MK20. I believe I've seen the brass tipped one and a dull stainless tip. The brass tipped MK20 piston was a spectacular creeper, so if the only MK10+ pistons are also brass tipped, my interest in them would take a nose dive. If, however, there's a newer style MK10+ piston similar to the MK25 composite piston, I'd get one of those. It could be a great performing first stage, something SP should consider re-issuing along with the G250V.

 

[redacted]

The IP creep problem needs to be corrected.

But the freeflow "problem' you describe may just be the first time you have gotten your 2nd stage tuned correctly. If you are going to get maximum performance, they should freeflow a little when you handle them badly. Use the adjustment knob to control it when not in your mouth, and enjoy.

 

[oncor23]

Here is my recent test...again using my cheap IP gauge.

at purge....pops back to 130psi
after 45 sec = 140
after 60 sec = 142
after 2 min = 148
after 3 min = 152
after 5 min = 158

That was it...I do believe the R190 started to leak air slowly as the Mk10+ hit 158.

The old piston looks to be solid stainless. I talked to a shop tech at my LDS and he told me they didn't have any brass tipped pistons for replacement...and had not used any, at least for the Mk10 in a long time. So, I'm guessing the one that's in there is steel. The shop tech mentioned that the body of the Mk10 could be worn...or scored...and that would result in creep. Last year, last time I checked this Mk 10+ with my IP gauge, it was not creeping...or if some, just a little. Nothing like this. Frankly, I think they did something to it during the last service. Or the HP seat is bad.

So, my rig is going back to the shop and I will let you all know the verdict. Hey Halocline, if they declare it DOA, I will happily trade it for your Mk10. Yes, I will tell you exactly what they say is wrong. In any event, I could always send it to you and you can decide whether it is worth the trade. Since I don't do regulator repair, if the shop can't fix it, it becomes an expensive paperweight for my purposes. I suppose I could also take it to another shop where most of my relatives live. I visit there often enough that having the service done there would not be much of an imposition. Both my currant LDS and this other shop are ScubaPro certified.

 

[halocline]

Okay, so they replaced the piston, but not on this service? Wear in the body and/or scoring won't cause creep. It might cause a leak; most frequently someone mangles the HP o-ring journal removing the old o-ring, and the result is HP air leaking into the ambient chamber. If there's scoring (usually due to corrosion or careless techs) in the ambient chamber where the piston head o-ring sits, IP air would leak into ambient. That would result in the IP dropping a bit until the piston gets pushed off the seat, which causes a rapid re-lock up, then slow IP drop again, etc...

There's only one place HP air leaks into the IP chamber, that's at the piston/seat interface. It's either a bad piston or bad seat. If the tech said "MK10" not MK10+, he should know that it's an entirely different piston and a MK10 piston will definitely NOT work with the MK10+ seat. They're not that dumb, are they? He must have meant MK10+.

Being SP certified means someone took a one-day course that nobody has ever failed. Not exactly 'rigorous' training....so the tech could be excellent or terrible at your store. There seem to be plenty of both at dive shops around the country!