Stiff breathing MK25/G250

[Hank49]

Also got my MK20 back. It was making a high squeal sound (air leak) coming from the piston area. I had replaced the piston head O ring but it started doing it again after a few minutes. This reg had sat unused for a while and the piston had never been dropped on the floor or anything, but the guy said he had to put in a new piston. It works so I guess he was right but that sounds odd. How could a piston go bad sitting on a shelf in a reg that has at least 800 dives on it before that?

 

[Web Monkey]

Well, I finally took the G250 to my repair guy. He couldn't fix it. I mean, it works...but it's a bit stiff. We replaced some parts but the vacuum guage he hooks to for testing resistance still read the same. 2... of whatever the unit of measurement is vs 1 or so for a smooth reg. I guess you do get "Monday" regs sometimes. Plus, the face plate doesn't screw on flush. It almost looks cross threaded. Kind of a bummer when you pay for a premium reg. And it came from an online store that doesn't do the warranty.

You need a better tech. There's no such thing as a "Monday reg". It's just a little pile of parts, some of which may need to be cleaned/replaced/adjusted.

While you're probably out of luck with the warranty, you're certainly not out of luck getting it fixed.

Just look for a big ScubaPro shop in your area that does a ton of service, and you'll have it working like a dream in no time. If you can't find anybody, I have a link to the shop I use on the homepage my website. They do an absolute boat-load of SCUBAPro sales and service, and fixed my MK1 so it works better than the day it was made.

Terry

 

[DA Aquamaster]

Well, I finally took the G250 to my repair guy. He couldn't fix it. I mean, it works...but it's a bit stiff. We replaced some parts but the vacuum guage he hooks to for testing resistance still read the same. 2... of whatever the unit of measurement is vs 1 or so for a smooth reg. I guess you do get "Monday" regs sometimes. Plus, the face plate doesn't screw on flush. It almost looks cross threaded. Kind of a bummer when you pay for a premium reg. And it came from an online store that doesn't do the warranty.

If the purge cover looks cross threaded it probably is and if it isn't it should be replaced because it should not look that way.

If it is still breathing in 2.0" of water range it still needs work. The spring in the second stage may be too stiff or the orifice may be damaged requiring excessive spring presure to stop it from freeflowing. A good tech working on the reg could tell the difference by how it responds to adjustment and either way could resolve the problem.

It's possible the lever may be bent or the tabs misaligned but that is a distant third in terms of likely culprits.

 

[Couv]

Also got my MK20 back. It was making a high squeal sound (air leak) coming from the piston area. I had replaced the piston head O ring but it started doing it again after a few minutes. This reg had sat unused for a while and the piston had never been dropped on the floor or anything, but the guy said he had to put in a new piston. It works so I guess he was right but that sounds odd. How could a piston go bad sitting on a shelf in a reg that has at least 800 dives on it before that?

Hank,

The most likely culprit is the piston stem o-ring, but having said that, I think the MK-20 has a composite piston and I know of at least one other person who had to replace it. There is also a set of guide bushings that may be suspect.

Anyway, it is more likely the piston stem o-ring grew lonely during it's non use and died. I hope the tech replaced this first. I hate to ask, but did he charge you for a new piston?

couv

 

[DA Aquamaster]

The piston stem o-ring and guide bushings are annual service replacement items and should have been replaced before the piston or at least with the piston. On the older Sp first stages (pre Mk 15) it was possible for the first stage body to wear to the point that the reg could leak in this area even with a new stem o-ring and that is the issue that the replaceable bushings resolve.

The last piston used in the Mk 20 was the same composite piston used in the Mk 25. On very rare ocassions they can leak but the leak would be on the low pressure side and 145 psi will generally not produce a high pitched squeal - just a few bubbles out the ambient pressure holes.

 

[Hank49]

There was another face plate in the shop that I put on my case and it misaligned also. I suppose he could have cross threaded it but there was no obvious damaged threads. I had the cover off a couple times and never noticed it before. It's on and holding the diaphram in place though. He didn't have an extra spring to try but replaces just about all the other parts with no effect. He also said mine is a cold water setup.??
The MK20 had a bad piston head O ring when I opened it up the first time it made the squealing sound. I replaced it and it worked for about 10 minutes and started again. I had also replaced the stem o ring. The good news is he only charged me US$25 for all the work on both regs. He told me he was sorry he couldn't fix the G250. I guess I'll have to take it up to the US and get if fixed because this guy is the only show in town. He's kind of retired but says he's a certified SP tech and he did fix my compressor.

 

[tedj01]

You can always have it shipped or shipped to SP to let them sort out the problem. If you do detail problem and attempts to resolve it. I realize you have higher shipping costs but I had to do it with one first stage that just would not function to specs. Mine was not a dangerous problem, just performance. SP after having local dealer replace everything in the reg and then doing it again at SP - eventually SP replaced the 1st stage.

SP has had me as a loyal customer for the attention they have shown to problems - mine and others I have been aware of.

 

[Hank49]

I'm going to buy another second stage...maybe the S555, when I go to the Philippines in late Nov. For some reason, they're cheap there. I have no other backup now since my son took my Atomic B1 second stage. Then I'll ship the G250 to get it straightened out. I just did a dive this morning with the "lemon" G250 though and it worked fine and even breathed a little better so no worries. It functions.