SP MK 10 PLUS: please help ID

[Texfrazer]

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.

I thought that I'd read that he'd used a sting-ray's barb, not an urchin spine, but that just goes to show you can't trust everything the internet tells you.

 

[Couv]

I thought that I'd read that he'd used a sting-ray's barb, not an urchin spine, but that just goes to show you can't trust everything the internet tells you.

.....yes, internet you only get half the story. One must have a buddy to buddy breathe, I was solo diving.....

 

[Zung]

The version I heard: he was breath holding while coning a baby remora to suck the o-ring out! Honest to God!

couv:
PM sent

 

[Zung]

... he told the remora it could dispose of his Mk5/109.
He lied.

 

[Texfrazer]

... he told the remora it could dispose of his Mk5/109.
He lied.

You must have meant a 109 converted to a Balanced Adjustable.

 

[Couv]

.....shhhhh, my mentor (awap) might wag a disapproving finger at me for doing an unnecessary conversion.

 

[Zung]

Gents,

I'd like to return to my Mk20/G250 #2 for a sec.: service 1 year ago by a LDS, 4 dives since, this guy takes 20 sec. to get back to nominal IP (135 PSI) after a purge, whereas the Mk20/G250 #1 which had seen much more use, takes less than a sec. Is it possibly because #2's got the dreaded mid-production brass tipped piston?

There's a guy from Austria who sells a piston on eBay for $42, the pic is attached below. Is this the good composite one?

Thanks

 

[Couv]

....Grasshopper, it is time for you to sell your MK20ies on eBay and buy a few real regulators....I see a MK 5 in your future, perhaps a MK10, and if you behave and refrain from buying an expensive pistons you don't need maybe even a real second stage made of metal, like all real regulators.....

 

[redacted]

Gents,

I'd like to return to my Mk20/G250 #2 for a sec.: service 1 year ago by a LDS, 4 dives since, this guy takes 20 sec. to get back to nominal IP (135 PSI) after a purge, whereas the Mk20/G250 #1 which had seen much more use, takes less than a sec. Is it possibly because #2's got the dreaded mid-production brass tipped piston?

There's a guy from Austria who sells a piston on eBay for $42, the pic is attached below. Is this the good composite one?

Thanks

That is the composit piston and $42 is not a bad price assuming it is new.

The question on #2 is what does the IP return to immediately after the purge. Ideally, it would immediately return to the set value within spec and lock up. If it does not lock up at that value, then the question is how much creep primarily and over what period of time secondarily. In your case, if it quickly returns to 130 and then creeps up to 135 over whatever period of time that is not too bad. If it is an older piston, that is a rather common mushy lockup. But if it is stopping below 125 creeping quickly to 130 (2-3 seconds) and then slowly creeping to 135 you would have a bit more of a problem but still workable and mostly correctable with cleaning. But if you initial stop is below 120 with a slow creep to 135, then you are essentially working with an IP below spec, and probably not getting as good performance from you 2nd stage as you could. Since you breathing cycle is probably in the 10 to 15 second range, any creep after that time should not get to cause freeflow while in use. But, as I said before, the symptom can be expected to just get worse so usually best to correct anything more than 5 to 10 psi before it causes a performance problem.

 

[redacted]

Gents,

I'd like to return to my Mk20/G250 #2 for a sec.: service 1 year ago by a LDS, 4 dives since, this guy takes 20 sec. to get back to nominal IP (135 PSI) after a purge, whereas the Mk20/G250 #1 which had seen much more use, takes less than a sec. Is it possibly because #2's got the dreaded mid-production brass tipped piston?

There's a guy from Austria who sells a piston on eBay for $42, the pic is attached below. Is this the good composite one?

Thanks

That is the composit piston and $42 is not a bad price assuming it is new. There is an o-ring sitting in the middle of that plastic and metal sandwich that will eventually fail. I rebuilt one that failed on me but the scubapro solution is a new piston when that occurs.

The question on #2 is what does the IP return to immediately after the purge. Ideally, it would immediately return to the set value within spec and lock up. If it does not lock up at that value, then the question is how much creep primarily and over what period of time secondarily. In your case, if it quickly returns to 130 and then creeps up to 135 over whatever period of time that is not too bad. If it is an older piston, that is a rather common mushy lockup. But if it is stopping below 125 creeping quickly to 130 (2-3 seconds) and then slowly creeping to 135 you would have a bit more of a problem but still workable and mostly correctable with cleaning. But if you initial stop is below 120 with a slow creep to 135, then you are essentially working with an IP below spec, and probably not getting as good performance from you 2nd stage as you could. Since you breathing cycle is probably in the 10 to 15 second range, any creep after that time should not get to cause freeflow while in use. But, as I said before, the symptom can be expected to just get worse so usually best to correct anything more than 5 to 10 psi before it causes a performance problem.

Oops, I thought I had gone to edit.