Attention MK-15 aficionados

[lexvil]

Has anyone checked an Atomic seat for size/compatibility? I no longer have anything MK 15 but I seem to remember them being similar

 

[lowviz]

Thanks guys! All that (above) puts these regs into perspective. I use MK15's for local river dives where I could stand up and use the big blue tank in the sky if they croak. I've standardized on MK-17's but I love these for singles in harsh silty conditions.

I’m still hopeful HP seats can be found or “produced” when I need one.

I started working on SPEC boots, @uncfnp is <still> loaning me one, @raftingtigger taught me how to make all sorts of polymer castings. Never got the finish line on the boots as repair kits became harder to get.

I still like these regs, working on a tool for the internal snap ring. It would be fun to find a way to keep them up and running.

Does anybody have an MK15 with the original hex key adjustment? I'll buy it for a reasonable price...

 

[JamesBon92007]

@JamesBon92007 Does your MK15 have a hex key hole on the hp seat retainer or does the retainer have 2 pin holes? Either way, have a look at the last page of the attached manual for some important seat/retainer compatibility information.

It has the two pin holes and the seat in the diagram looks like the one in the repair kit. I don't have it apart yet. Anyway, it appears to have been "upgraded" judging from what I've seen and read. I have a feeling I'm missing something...

 

[Couv]

@JamesBon92007 does the seat have an o-ring around it, or does the o-ring sit on top of the seat? Have a look at the diagram below. The "upgrade" is on top. Note the bushing eliminates one the seat carrier's snap ring (there is still a snap ring in the body though.) Also note the seal goes between the bushing and seat.

The pre-upgrade assembly has a snap ring holding the seat in place and the seat itself has a seal around it just like the MK20/25.

I'm pretty sure I "upgraded" a MK15 a couple of years ago without replacing the seat retainer; i.e. installed the new components into the old hex headed retainer. I also installed the upgraded parts into the body. Therefore, if one has all of the components, either retainer should work with the old or new configuration.

 

[lowviz]

I'm pretty sure I "upgraded" a MK15 a couple of years ago without replacing the seat retainer; i.e. installed the new components into the old hex headed retainer. I also installed the upgraded parts into the body. Therefore, if one has all of the components, either retainer should work with the old or new configuration.

This is most interesting. I would like to keep this reg alive a bit longer for historical sake if nothing else.

So I'm looking for the parts shown below and an original spring, not a red one...

 

[Couv]

@lowviz So you are looking to "downgrade" one of your MK15s? The only reason I can think of is that with the older setup one can more easily adjust the IP.

 

[lowviz]

So you are looking to "downgrade" one of your MK15s?

Yes, exactly. I have all the MK-17's for coldwater backmount doubles, sidemount, and singles that I will ever need. They kinda suck for singles, though. No reason that I couldn't use 25's other than I require environmentally sealed regs for the kind of diving that I do.

I'm a gearhead, and totally get the progression of the MK-15. Came to really appreciate it, it would have kept going if the world was full of coldwater divers. So I want an 'original' (3000 psi max) MK-15 reg. Maybe just to keep one of them alive somewhere.

I appreciate the balance of gear and diving. Sometimes gear rules, sometimes it is all about the dive and I don't care what is strapped onto me.

Most divers' mileage will vary...

 

[Couv]

@lowviz Check your email.

 

[JamesBon92007]

@JamesBon92007 does the seat have an o-ring around it, or does the o-ring sit on top of the seat? Have a look at the diagram below. The "upgrade" is on top. Note the bushing eliminates one the seat carrier's snap ring (there is still a snap ring in the body though.) Also note the seal goes between the bushing and seat.

The pre-upgrade assembly has a snap ring holding the seat in place and the seat itself has a seal around it just like the MK20/25.

I'm pretty sure I "upgraded" a MK15 a couple of years ago without replacing the seat retainer; i.e. installed the new components into the old hex headed retainer. I also installed the upgraded parts into the body. Therefore, if one has all of the components, either retainer should work with the old or new configuration.
View attachment 555899

I don't have it apart yet (maybe Thursday) but wow, thanks for the head's up. It didn't occur to me yet that someone might have done only part of the upgrade. I should know better The kit I have contains a flat disc type seat so that should mean it sits on top of the O-ring. I don't know which seat is in there right now, but my guess would have been the one that sits on the O-ring, judging from the seat retainer that's on it now. The kit also contains a copper snap ring which I think I read was an upgrade from a SS snap ring. I will, of course, have all my info printed out and in front of me before I take it apart. Considering the condition of the LP seat on the old poppet anything is possible.

I switched tanks and the second-stage-getting-stuck-open problem seems to be better. ScubaPro says to check everything at 300 psi too so I still need to do that. How close does that need to be? That sounds like old J-valve stuff. I think my tank was below the IP pressure and there might not have been enough pressure for the LP seat to seal because it was leaking a little even with the adjustment screwed all the way down and it has a brand-new LP seat and poppet and the volcano valve looks fine.

 

[Couv]

I don't have it apart yet (maybe Thursday) but wow, thanks for the head's up. It didn't occur to me yet that someone might have done only part of the upgrade. I should know better

Chances are if a new seat retainer was installed, the upgraded seat and other parts of the upgrade kit were also installed. I "upgraded" one with all of the new components except the seat retainer.

The kit I have contains a flat disc type seat

Flat disc, but with a concave on one side and no groove around the outside right?

The kit also contains a copper snap ring

The beryllium copper snap ring holds the piston bushing system in place. The other snap ring that held the seat in place has been eliminated.

I switched tanks and the second-stage-getting-stuck-open problem seems to be better.

First things first. Always have a steady IP before trying to sort out any second stage issues.

I think my tank was below the IP pressure and there might not have been enough pressure for the LP seat to seal

No, no, no...the second stage is a downstream valve. I suggest starting a new thread for your second stage issues in the DIY forum. Something is not right with the second stage.

ScubaPro says to check everything at 300 psi too

Yes, the IP must be in specs at both high and low supply pressure.