scratches inside first stage? scubapro mk2

[r32gtr]

Hi ScubaBoard,

I just bought a used ScubaPro Mk2 and opened it up for service and noticed these scratches on the inside. It looks like they sit very close if not on where one of the orings for the piston sits. I was wondering if anybody has seen anything like this and if it is going to cause any problems?

 

[guruboy]

Do you mean the circular rings on the flat part? That’s probably just from machining.

Maybe you could mark the scratches you’re talking about.

 

[r32gtr]

Hello All,

They seem to be right in the area where the first stage oring sits so I am concerned and wondering if anyone has seem anything like this before and if it is an
issue? Also I found a total of 4 shims on the spring, I am wondering if this is a sign the spring also needs replacing.

I attached some pictures to show the problem. I am wondering if I should spend the money on the service kit vs returning the item.

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A ScubaBoard Staff Message...

Post text edited slightly for clarity with a merged thread.

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[herman]

Those appear to be machine marks, tech caused ones don't tend to be long and straight like those are so my guess is they were done at the factory. Based on the amount of magnification, they don't appear to be too deep or wide. Radial grooves like those tend to seal Ok with orings if they are not too wide/deep, although they may shorten the life of the oring. Linear grooves are the ones that give you the worst problems.

If the original oring looks OK, I would lightly lube it, reinstall the piston, assemble the reg normally and test for leaks. If it leaks, it's most likely going to be a very slow bubbling rather than an audible leak so it will require submerging the reg to look for leaks. If the old oring is questionable, it's a #008s so finding one should not be a problem. If it passes that test, I would rebuild it and keep an eye on it for leaks.

 

[buddhasummer]

Hello All,

I just bought a used ScubaPro Mk2 and took it apart to check the condition and I found these scratches in the bore where the small end of the piston fits in. They seem to be right in the area where the first stage oring sits so I am concerned and wondering if anyone has seem anything like this before and if it is an
issue? Also I found a total of 4 shims on the spring, I am wondering if this is a sign the spring also needs replacing.

I attached some pictures to show the problem. I am wondering if I should spend the money on the service kit vs returning the item.
View attachment 499945 View attachment 499947 View attachment 499948

@rsingler

 

[rsingler]

Thanks, Buddha!
Yeah, those dings are very close to, if not right at the mating surface of the piston shaft o-ring. I would be very surprised if that didn't bubble out the ambient holes when pressurized, even if IP held.
I'd send that one back for sure. Even if it seals right now, the breaks in the chrome will corrode quickly in the portion that's exposed to sea-water via the ambient holes.

Whenever I get new (used) gear, I throw it on a tank and check the stability of the Intermediate Pressure. If I can, I'll use a small pony bottle and submerge the reg in a sink.
Passing those two tests gives you a lot of confidence before you tear it down.
Sorry, @r32gtr !

BTW, up to 6 shims are now permitted on the Mk2 EVO. I wouldn't sweat 4 on an older model, if it yields the IP you need.

 

[rsingler]

We may have to agree to disagree, @herman . An interesting question. You're certainly right about a radial mark being more likely to seal than a vertical one, but this pic suggested chrome loss to me, and while flash pics are often deceptive it seemed deeper than a machine mark. Maybe I'm imagining it, but that point under the arrow seemed to have no chrome.

@r32gtr , if the marks are chromed, I'd take Herman's advice and lube and reassemble it (maybe with a new 2-008 oring), and check the seal. If you can see brass or green in the bottom of the mark, I'd send it back.

 

[r32gtr]

Thank you for the reply. The marks definitely go through to the brass (good eye!) it is hard to take a picture of but easy to see in person. I decided to take some pictures of the piston under a microscope to see if I could find what was causing the marks, results are posted below.

 

[rsingler]

Good luck returning your new toy!
Sorry, amigo!

My guess is that the previous "technician" used a flat-blade small screwdriver to remove the shaft o-ring.
When you drink the ScubaBoard Kool-Aid and start repairing your own regs, don't be that guy!

 

[herman]

Yea, with the photo of the piston I agree with you. Nothing like a ham fisted tech to mess up a reg.