Scubapro MKV piston recall?

[Goatman1225]

Hey all,

I took my regs in to be serviced recently (a Scubapro MKV and an upgrade SP109), and was told by the the shop that the MKV has a recall on the piston, and that a new part was unavailable. I've done quite a bit of research and haven't been able to find any information on the topic, and was wondering if this sounded familiar to anyone here. I've become quite fond of the regulator, and do not wish to scrap it if I don't need to. Thanks!

 

[lexvil]

Sharp pistons can cut into the seat and lock up, no new pistons for years, I think there are seats that replaced the originals to mitigate this. There are better first stages available and second stages but those have followers.

 

[Goatman1225]

Sharp pistons can cut into the seat and lock up, no new pistons for years, I think there are seats that replaced the originals to mitigate this. There are better first stages available and second stages but those have followers.

Well thats too bad to hear. Thanks for confirming what they said though. Any favorite recommendation for a new 1st stage?

 

[lexvil]

What to replace it with is pretty wide open the MK 25 is very similar but I prefer non swivel firsts like the MK 11 or 17 also many other brands to choose from.

 

[Scuba Lawyer]

I'd like to see the recall notice. I've rebuilt my Mk5/109 quite a few times and never had a piston problem. M

 

[halocline]

Well thats too bad to hear. Thanks for confirming what they said though. Any favorite recommendation for a new 1st stage?

Sorry about this, but you should ignore the post about there being a problem with the sharp MK5 piston. They are the most reliable 1st stages I have ever worked on, I have used them in cave diving for years. There is not a problem with the MK5 piston cutting into the seat, never has been. Similarly, the upgraded 109 is an excellent 2nd stages, that I also use in cave diving, despite having a closet full of more modern 2nd stages.

The problem you encountered was almost certainly with the shop where you brought the regulator for service, not with the regulator.

There was a recall on the early models of the MK15, a much later 1st stage. In that case there was a failed attempt at an external IP adjustment, which caused damage to the HP seat. That seat material (different than the MK5/10 seat) was also faulty, and there were some cases of the seat essentially being destroyed by the piston edge. However, that was taken care of by getting rid of the external IP adjustment and changing the seat material. But none of this has anything to do with a MK5. I assume you’re sure that’s what you have, not a MK15, correct?

I have heard that at some point very early in the MK5’s development SP redesigned the piston to have a ‘step’ at the base of the piston shaft, and that step prevented the piston from traveling too far into the body of the regulator. I have seen a few of these really early pistons, but only on the original 2 LP port/1 HP port version of the MK5, which also has a yoke that’s not suitable for modern tanks. The later MK5s (which is what people dive these days) have 4 or 5 LP ports, 2 HP ports, and a heavy yoke that’s fine for 3000+ psi tanks.

If you want to post a photo of your MK5, I’m sure any number of people can confirm that yours is ok. If you want to get it expertly serviced, you can contact rsingler on this board and he’ll do it.

 

[lexvil]

Dealing with a vague memory, I seem to recall something about the flat seat and the piston cutting into it, they changed to the cone seat, not the piston being recalled. Still if a piston is needed they are NLA except used and if memory serves the MK 7 uses the same piston.

The MK 5 was a great regulator and I’m sure the dinosaurs enjoyed the bright nights 25 million years ago, just before…

There are many better options than trying to revive the T Rex, it’s time has past, this includes the 109.

They can be kept operational by an enthusiast but have no intrinsic value, just offer them for sale and look at the offers you’ll get. You can buy a beautiful MK 5 109 for $40 put $100 worth of parts into it and sell it for $40, the people who love them have 20 of them but the world has moved on

 

[Goatman1225]

Sorry about this, but you should ignore the post about there being a problem with the sharp MK5 piston. They are the most reliable 1st stages I have ever worked on, I have used them in cave diving for years. There is not a problem with the MK5 piston cutting into the seat, never has been. Similarly, the upgraded 109 is an excellent 2nd stages, that I also use in cave diving, despite having a closet full of more modern 2nd stages.

The problem you encountered was almost certainly with the shop where you brought the regulator for service, not with the regulator.

There was a recall on the early models of the MK15, a much later 1st stage. In that case there was a failed attempt at an external IP adjustment, which caused damage to the HP seat. That seat material (different than the MK5/10 seat) was also faulty, and there were some cases of the seat essentially being destroyed by the piston edge. However, that was taken care of by getting rid of the external IP adjustment and changing the seat material. But none of this has anything to do with a MK5. I assume you’re sure that’s what you have, not a MK15, correct?

I have heard that at some point very early in the MK5’s development SP redesigned the piston to have a ‘step’ at the base of the piston shaft, and that step prevented the piston from traveling too far into the body of the regulator. I have seen a few of these really early pistons, but only on the original 2 LP port/1 HP port version of the MK5, which also has a yoke that’s not suitable for modern tanks. The later MK5s (which is what people dive these days) have 4 or 5 LP ports, 2 HP ports, and a heavy yoke that’s fine for 3000+ psi tanks.

If you want to post a photo of your MK5, I’m sure any number of people can confirm that yours is ok. If you want to get it expertly serviced, you can contact rsingler on this board and he’ll do it.

Hey, I appreciate you taking the time to respond here. I just got back from the shop that has my regs, and they went over the reg with me in great detail. He showed off a few things:

* Despite having the 5LP port cap and the thicker yoke, my reg had the straight shaft piston. In his repair diagram he had a note saying that those pistons were unsafe to use. He actually called scubapro with me there asking for more details, and they again said not to use it.

* The spring has gone soft, and despite the excessive amount of shims in my reg it was still barely in IP spec

* it was missing some flat washer that was supposed to be present (number 5 on the diagram i think), that is supposed to keep the HP seat in place. In its place some random 0 ring was redneck-ed in. The replacement part seems to be unavailable.

In addition to the above, he showed me my 109s diaphragm, which looks very worn and again seems to not have replacements available. All that has me strongly considering a new MK19 and D420 set they had on hand for a fantastic deal. Again though, would love a second set of eyes / opinion here. Thanks

 

[lexvil]

A note on your replacement offerings, I would ask for a deal on a G260 in place of the D420, I’m a big fan of the D420 but SP is showing every sign of dumping that regulator from the line up, I have 4 of them and expect to have them in service as long as I dive the G 260 is one of their best all around second stages, tried and true design and built like a tank, easy to service.

I don’t like the MK 19 only for cosmetic reasons, to long with the turret but a solid design.

 

[Nemrod]

The change in the piston was that a shoulder was added to prevent over travel. The over travel happened (note I used singular case, maybe it was more than once) when the valve on an HP (cave fill) cylinder was slammed open possibly assisted by (incorrect) excessive IP. The piston knife edge managed to cut into the seat. I have Mark 5 firsts and clone Mark 5 firsts and will continue to use them with no worry.

I place this possible failure in the same category as bent pins in a Conshelf. It may have happened, I saw one with my own eyes. The things that can contribute are the wrong pin (over length), slam opening, hydraulic lock due to water being in the first stage.

I have seen a Nylon bushing machined to act as the shoulder on a Mark 5 piston. I wonder where I may have seen that. It is not worth worrying over IMO.