SP MK-20 - IP Creep

[redacted]

Dressing a metal orifice

 

[redacted]

Scubapro Mk 20 Pressure Creep

 

[rhwestfall]

Wow, thanks for the thread bump. I was under too short of a timeframe to deal with the "issue" and the regs did fine for some simple recreational splashes. I found composite pistons, but haven't installed them yet as I got distracted with other projects... forgot about the other valuable "tidbits" that were in this thread.

Ironically, one new issue is a MK-10+ that was exhibiting that "mushy" lock-up after rebuilding this weekend. It was "shot" when I got it, so no pre-rebuild data on it. Initial 130 ip, then slowly (sometimes, up to 5 minutes) to 150-155, then solid with 500 psi (need to get a fill). Was sure I did something wrong....

I had already packed the ambient chamber (by need, not by choice), so I was really frustrated that I would have to tear it back down.

That 10+ seat and the smooth edge piston stem are a PITA!

 

[Zung]

My full report is here.
Micro-mesh is all over eBay, just search for it; don't forget the dash.
halocline used to call himself mattboy a few centuries back, hence the trademark "mattmagic"

 

[NotSure]

I was rereading DA Aquamaster's last post and he mentions that the early MK10 plus and MK20 HP seats were a harder material. I think I would try a new MK25 seat in the MK10 plus if there's a chance that your MK 10 plus seat is old stock before messing with the piston. The best way to fix it is to convert it to MK10.

 

[rhwestfall]

Yeah, an old stock seat might be the reason, but the packaging had no "born on" date. It is the blister card and not the heat-sealed bags of old time..

The best way to fix it is to convert it (back) to a MK10.

This solution, though, is hardly worth the money... Why spend $20+ on a "new" piston, and $XX(?) for a seat carrier for a $50 regulator to go back to a MK-10? If I can't source a different seat, the reg will become a parts donor in the scrap drawer or parted out if someone is looking for those pieces....

I put it on 3k pressure last night, and it "locks" at 125, then creeps to the 145 spec, and settles in. Guess I'll look for a seat.

 

[buddhasummer]

Yeah, an old stock seat might be the reason, but the packaging had no "born on" date. It is the blister card and not the heat-sealed bags of old time..



This solution, though, is hardly worth the money... Why spend $20+ on a "new" piston, and $XX(?) for a seat carrier for a $50 regulator to go back to a MK-10? If I can't source a different seat, the reg will become a parts donor in the scrap drawer or parted out if someone is looking for those pieces....

I put it on 3k pressure last night, and it "locks" at 125, then creeps to the 145 spec, and settles in. Guess I'll look for a seat.

How did you get on in the end?

I just rebuilt a MK10 Plus, new stock piston and new stock service kit with the black seat, interestingly the kit didn't come with a seat O ring, lucky I had one on hand. I have numerous schematics for the Plus and it seems SP were forever changing what parts were required annually and what weren't. The documentation in the kit said it did come with a seat O ring however, guess the kit packer had a hangover that day.

Pressurizing at around 2000 PSI, I don't have a full tank, it starts at around 128 drifts to just shy of 135 within about a minute, then very slowly over the course of a couple of hours drifts to around 140. It certainly doesn't lock up like my MK10 and the drop in ip on demand is much higher.

I've tried cycling it and have left it pressurized so will see what it's at after work in about 11 hours.

If I shut off tank and bleed down to 500PSI the ip actually increases not drops. Strange.

I've read various posts re mushy lock up and creep so am unsure if this the way it is or if I need to address "an issue".

Any ideas would be gratefully appreciated.

 

[guruboy]

If it doesn't exceed the 145psi spec, what's the issue?

 

[buddhasummer]

Not sure, just have never seen this type of slow drift/creep before. At this stage I'm not sure if it stops creeping after 140, guess I'll find out in about 7 hours when I get home.

 

[redacted]

If it doesn't exceed the 145psi spec, what's the issue?

Creep does not cure itself. While you should be able to dive 145, it is time to plan a fix.