Scubapro MK 15 opinions

[coldstroke]

I have acquired one never used except as a spare/backup. Please give me the scoop/pros-cons of this regulator.

 

[DA Aquamaster]

It offers Mk 20/25 performance and is very similar internally. The major difference is that the Mk 15 uses a lower bushing that is held in place with a C clip and the upper bushing is fixed. The Mk 20/25 uses a lower bushing that is held in place by spring pressure and the upper bushing is removeable. Techs did not liek the Mk 15 as it was a little harder to service in that you needed very narrow long reach pliers to reach and remove the c-clip.

The Mk 15 piston is very similar to the early M20 piston in being a one piece stainless steel design. The current Mk 25 piston is a composite design with a stainless steel stem and a plastic head. The all stainless steel piston is very durable, which is a pro, but the con is that SP is no longer making them so if you damage one, you have to check around to find a shop with one in stock. The good news is that unless you run big chunks of dirt or rust through your regulator it is virtually impossible to damage one.

Another potential pro is that there are still Mk 15/early Mk 20 SPEC boots floating around that would allow you to fill the ambient chamber with christolube - you can't do that with a Mk 25.

One thing to check is whether the seat retainer on the base is flat (flush with the rest of the base) or curved (indented a bit around the circumference compared to the rest of the base of the reg body). The older curved retainer was adjustable but was recalled and was limited to 3000 psi until replaced. The later flat retainer was approved for use to 4350 psi. By this time most Mk 15's should have the flat retainer.

 

[halocline]

I have one and I like it alot. I've rebuilt it and since I have the snap ring pliers it's as easy as any other SP balanced piston 1st. If you bring it to someone to rebuild, and they've never done one but are familiar with the MK25 (not an unlikely scenario), you should mention that the piston bushing that goes on the ambient (piston) side of the body is NOT replaceable. On my schematic it just shows the bushing and makes no mention of this. It was only due to DA's posts that I knew not to try to dig it out. That's a mistake I bet more than one inexperienced tech has made.

I also don't know if the MK20 bushing tool would work; I bought the MK15 bushing tool and I'm wondering if it would work on a MK20/25.

 

[DA Aquamaster]

It was only due to DA's posts that I knew not to try to dig it out. That's a mistake I bet more than one inexperienced tech has made.

I also don't know if the MK20 bushing tool would work; I bought the MK15 bushing tool and I'm wondering if it would work on a MK20/25.

You would be correct, more than one tech did indeed dig the bushing out - requiring a new regulator body. It's not a bad idea to mention that to any new looking tech who may have never worked on a Mk 15.

The Mk 15 tool is a bit too short to properly stack the 2 bushing and o-ring in the Mk 25, also since the bushings are retained by a spring in the Mk 25, you need the hollow end on the other end of the tool to keep them from getting pushed out when you install the piston.

 

[coldstroke]

I have one and I like it alot. I've rebuilt it and since I have the snap ring pliers it's as easy as any other SP balanced piston 1st. If you bring it to someone to rebuild, and they've never done one but are familiar with the MK25 (not an unlikely scenario), you should mention that the piston bushing that goes on the ambient (piston) side of the body is NOT replaceable. On my schematic it just shows the bushing and makes no mention of this. It was only due to DA's posts that I knew not to try to dig it out. That's a mistake I bet more than one inexperienced tech has made.

I also don't know if the MK20 bushing tool would work; I bought the MK15 bushing tool and I'm wondering if it would work on a MK20/25.

Which snap ring pliers do you recommend? Where can I buy a pair? Thank you.

 

[coldstroke]

Which snap ring pliers work well & where can I buy them? Thank you.

 

[DA Aquamaster]

Peterbuilt used to sell a good pair, but they are currently between owners. Most pairs will work if they are long enough, you just need to grind them down a bit so the jaws are narrower.

 

[halocline]

I have the ones from peterbuilt.

 

[superstar]

I got snapring pliers from Sears.

 

[akscubaduck1]

Work, Peterbuilt, Home, Sears as well!