SP MK 10 PLUS: please help ID

[redacted]

You know, I was looking at a micrometer just the other day and decided I didn't really need it. WRONG. So here I am doing these measurements with a ruler.

Picture of the 3 springs is in my photo gallery: ScubaBoard Gallery - Scubapro Springs

The spring on the left is from a Mk10 and is 25mm long. The spring on the right is from a Mk5 and is 26mm long. The center is unknown application and 27mm long. They all appear to fit in a Mk10 body and engage the piston OK.

 

[scubafanatic]

...boy, I wish I had even 10% of the mechanical apptitude you guys appear to have, that being said, what is the $ value of this 1st-stage, relative to the $ value of all the time/inspection/assembly/disasembly/reassembly/testing involved is resurrecting this unit? ...or is it just the challenge of it ? ......or a desire to keep all ones regs standardized ? ...or is it an especially awesome performer whose performance a new reg can't touch ? ....just wonderin'....

 

[redacted]

...boy, I wish I had even 10% of the mechanical apptitude you guys appear to have, that being said, what is the $ value of this 1st-stage, relative to the $ value of all the time/inspection/assembly/disasembly/reassembly/testing involved is resurrecting this unit? ...or is it just the challenge of it ? ......or a desire to keep all ones regs standardized ? ...or is it an especially awesome performer whose performance a new reg can't touch ? ....just wonderin'....

Dollar value is of interest only if I am using time that I could have used for earning. As it is, I am retired and payed just to breath (mil, civ serv, and SS) so I continue to earn my standard rate while working on my regulators. Same rate I get payed for participating on this board and for actual diving.

 

[Zung]

awap: ...I was looking at a micrometer just the other day...

I did the exact same thing and came to the same conclusion, even though these guys go for 25 bucks nowadays!

Thanks for trying. On my side, both springs appear to be identical.

I just swapped back the parts and checked the IP: i've got the exact same numbers (over time) as before the swap, so I'm getting away this time for disturbing something that works.

scubafanatic: ...what is the $ value...

I'm pretty careful with my time... at work (sadly, I have to work for a living).
After hours, I'm a born tinkerer and I have to mess with my gears, sometimes improving, sometimes degrading. But it's all in a learning process.

That being said, the $ value of this board is gigantic, and the lessons I learned in this thread testify to that. Even if you leave out all the mecanical technicalities, the high level story is:

I used to be a carefree diver, leaving happily the maintenance to some unknown guys somewhere and survived. With the kids being certified, I started realizing that 4 sets + 1 or 2 spare could mean a grand a year.

And so I looked into doing some of the work myself, found this board, learned a lot of stuff from the great folks here, i.e. my set works great probably because of the instant lockup and recovery, my wife's former set is less good because of the slow creep, and, most importantly, what should be done to keep your gear in great shape, and also why a LDS CANNOT afford to do the kind of work that's advocated here.

To me, this is worth more than gold, certainly more than the time I spent reading all of the previous posts.

In addition, there's something I (jokingly) tell my business friends when they complain that it's hard to keep up with all those new technologies: I say: it's 9PM, you've just put the kids to bed, what do you wanna do? Watch TV? Or do some research/studying?

 

[halocline]

I swapped the spring from Mk10+/G250 #2, no change.
Then spring + piston from the same: IP now down to 155 PSI!
This combination in the original body is worth 144 PSI, so there's still a little something, but the bulk of the problem is gone!
So I have to find another piston, or, better still, a downgrade kit!:depressed:

Thanks to all who helped!

Sorry to rain on the parade, but to me if you have 155 IP with no shims, you're still looking at a faulty spring or seat.

It would be helpful to know where the creep starts; you tap the purge or take a breath, the IP gauge needle drops, then comes up to a point when you stop inhaling, then stops momentarily, then slowly creeps, is that right?

If the initial stopping point is higher than 150 with no shims, then you have a problem that must be connected to the spring, or the wrong seat, or the wrong retainer. A problem with the piston will always be creep.

If you don't need the reg for a while, I'd just start checking out ebay for MK10 pistons and seat retainers. One nice thing about the MK10 kits is that they have three seats. If your spring is unusually stiff, you can try the tall seat in the MK10 kit once you find the MK10 piston. On my MK10s, that seat with no shims produces an IP of around 110 at the most.

 

[Zung]

That's right: after a purge, the IP goes rather quickly to 140 PSI and then slowly to 155 over 15 minutes.

Right again, since I have to replace the piston, it's the Mk10 parts I'll be looking for. I fully realize now why the non-Plus's are more desirable. Actually, I already have a couple of the Mk10 service kits on hand: I ordered them last year because I forgot I paid to upgrade my Mk10's to Mk10Plus 15 years ago

I'll also be looking for Mk5's; will post request for help for disposal if I could lay my hands on any.

 

[scubafanatic]

...OK, I see the motivation.....retired so have spare time....pride/perfection in one's work...saving $....don't get me wrong, I custom design/modify a lot of my own gear, mainly 'cause I'm a perfectionist...also, I have designed/deployed gear innovations the dive gear industry hasn't thought of yet....my quest for the perfect gear! ......but while I customize the hose layout/hose attachments on my regs, I don't 'go inside' them......guess I'm just nervous messing with anything holding back 3000 psi!

 

[Couv]

Zung,

I'm pretty sure I have a MK 5 (and a cool MK 7 honker) in my closet that has been re-built. If you are interested PM me. But I must warn you....this is life support and I'm not a certified tech!


Scubafanatic,

I just consider it a hobby. Getting something to operate at it's peak performance, or to bring a reg back to life that a dive shop would pronounce dead gives one a lot of satisfaction. Also, because my family is growing into a 3 diver family, and we need 3 regulators each, not to mention computers, gauges……ooops, got carried away there…. At any rate, here is a stolen quote from Thal "It's life support, that's why I service it myself." Personally, I don't view it as life support, but it is important.

I once flew halfway around the world to stay on a live aboard dive boat in Truk. My regulator started to leak out of the ambient pressure holes. With a pair of Channel Lock pliers, a vice and a piece of tape (to put over the piston) I was able to swap out the discrepant o-ring. Sure, my regulator still has those scars from 20 years ago, but I still use it. Sure, I could have rented a piece of junk from the boat, but because I had faith in my ability to repair it, why would I have bothered?

Come to the dark side.

Couv

 

[halocline]

I once flew halfway around the world to stay on a live aboard dive boat in Truk. My regulator started to leak out of the ambient pressure holes. With a pair of Channel Lock pliers, a vice and a piece of tape (to put over the piston) I was able to swap out the discrepant o-ring. Sure, my regulator still has those scars from 20 years ago, but I still use it. Sure, I could have rented a piece of junk from the boat, but because I had faith in my ability to repair it, why would I have bothered?

Come to the dark side.

Couv

What Couv is not telling is that he repaired the reg during a dive, while buddy breathing, using an urchin spine as an o-ring pick.

 

[halocline]

...boy, I wish I had even 10% of the mechanical apptitude you guys appear to have, that being said, what is the $ value of this 1st-stage, relative to the $ value of all the time/inspection/assembly/disasembly/reassembly/testing involved is resurrecting this unit? ...or is it just the challenge of it ? ......or a desire to keep all ones regs standardized ? ...or is it an especially awesome performer whose performance a new reg can't touch ? ....just wonderin'....

It's a hobby, just like diving. You're supposed to spend excessive amounts of time on it for no particular reason.

Old SP regs like the MK5 and MK10 with 2nd stages like the balanced adjustable, G250, and D series are amazing performers, certainly as good as anything I've tried or worked on. Another nice thing about working on your own regs is the feeling of control. One 10-minute conversation with the "tech" at my LDS several years ago convinced me that I was better off working on my own regs.