Looking for help with Reg ID - Mk5?

[Hethen57]

I have serviced a couple of MK2 and MK5's, but this one has a light blue o-ring below the piston that I have not seen on any other MK5's and it did not come in my MK5 service kit (I probably have something that will fit in my generic o-ring set). Is this actually a MK5 and can someone tell me about this o-ring seal in the piston/balance chamber and the approximate vintage of this reg? Does it environmentally seal the chamber as an alternative to the spec grease? Should I be able to use a generic 70 duro o-ring of the correct size for a replacement?

These photos show the reg, but it looks a little different because I did not fully re-assemble and tighten body parts for the photos.

 

[Hethen57]

Also: it has 2 hp ports on the main body, 4 lp ports around the sides of the turret and one port on the end.

 

[James79]

Looks like a mk10 to me, mk5s have the ambient holes on the removable portion, not the main body.
My advice is always worth what you paid for it!
Respectfully
James

 

[Hethen57]

James79, I think you hit the nail on the head...its a MK10. To be honest, I just picked this one up for the heavy yoke so that I could replace the lighter one on my MK5, but it was so clean I figured I would leave the MK5 as a back-up. Now I will order the MK10 service kit from VDH.

Is there any major pros or cons between the MK5 and the MK10? Both of mine are clean, so I'm just wondering which one would be the preferred 1st stage to connect up to my Balanced Adj 156 second and 108 safe second to complete my retro ScubaPro rig.

 

[James79]

I've never had my hands on a mk10.... My son uses a mk5 and I use Conshelf 1st stages. I do think you should give me the 156 and 108 for proper disposal though! Lol

 

[Couv]

Hi @Hethen57 ,

Yes, just as my friend from LA (Lower Alabama) points out, that is a MK10, not a MK5. The large o-ring you see (-117) is required in the MK10 to seal the cap to the main body as the piston head seal is contained in the main body unlike the MK5 which serves to seal the cap as well as the piston head.

I'm guessing it's an early model due to the banana yoke screw and no SPEC groove.

No to the environmental seal question. Water enters the ambient chamber.

Most of the advantages found in a MK10 can also be found in the late model MK5s:

Heavy yoke, 2 standard size (7/16") hp ports, 5 low pressure ports on a swivel turret.

Very nice find. If you need more (who doesn't?) PM me.

 

[Hethen57]

Thanks again for the assistance! I know my collection doesn’t hold a candle to what most of you guys have, but it is gettin pretty complete in terms of SP and USD specimens of various vintages and they all work great.