MK10 Rebuilding Mods and Best Practices

[Timmyjane]

Thanks for the explanations and clarification @rsingler.

I have no intention of experimenting with the 25 or 18. Was just thinking they might be better suited as they are much newer. I haven't really studied them.

Sounds like the knife edge is the key to the MK10. I would suspect that goes for most piston regs? I'll have to find a guide on that process. The first reg I opened had the cone seat. I think I am going to go ahead and get 3 service kits and start with fresh cones and all Scubapro parts. I can use replacement o-rings down the road.

I'll look into the red spring and see what that is all about.

 

[Timmyjane]

What signs would show that the HP seat needs to be replaced?

 

[James79]

What signs would show that the HP seat needs to be replaced?

IP creep, generally. If IP is mushy (i.e. goes to 135 immediately then slowly to 140 over a couple seconds and stops there) that could be knife edge imperfections or break in of a new seat (amongst some other possible culprits). But if the IP is slowly continuing to rise and doesn't stabilize, then either the knife edge or the seat have damage that isn't letting it seal... And the seat is intentionally the softer material.
Also, it is often recommended to replace the seat whenever you open it up... And if you aren't, then index mark the seat carrier to the reg body and the seat to the carrier. If the indent from the knife edge isn't lined back up perfectly, it creates a channel under the knife edge causing IP creep.

 

[lexvil]

You have a MK 25, why spend so much time and effort on the 10? Play with it but dive the 25.

 

[Timmyjane]

You have a MK 25, why spend so much time and effort on the 10? Play with it but dive the 25.

My wife is also learning to dive and I have a pony. I need to have several working regs. The 25 is on my list to tackle next for sure. Figured the 10 would be a good place to start learning how to service. I need to find a kit for the 25 also. Seems they aren’t as available to me as the 10 is.

 

[Mobulai]

Figured the 10 would be a good place to start learning

As a self identified self service noob, that’s exactly my plan good sir

 

[lexvil]

While the MK 10 is a good first stage, in my opinion the MK 25 is better if only because it allows some IP adjustment without breaking back into the guts, it’s a small thing but can be really nice when needed. If you hunt for used stuff you’ll be able to find older 25’s for about the same cost as a10 but the 10 is a good reg.

 

[Bloody Knuckles]

While the MK 10 is a good first stage, in my opinion the MK 25 is better if only because it allows some IP adjustment without breaking back into the guts, it’s a small thing but can be really nice when needed. If you hunt for used stuff you’ll be able to find older 25’s for about the same cost as a10 but the 10 is a good reg.

T-J,
On behalf of "Couv", welcome to the "dark side". (If you poke around enough on this site you'll understand).

A few things...If you're looking to save a few bucks, this future endeavor of yours is pretty much inline with buying a cow to save on milk. If you're looking for knowledge, guidance and an understanding of how these toys work, you've come to the right place. There is a wealth of information on this site associated with the MK10 and it's older sibling the MK5. The following authors will help you with that quest. (Couv, Rsingler, Halocline, DA Aquamaster, Awap (now redacted), Angelo Farina, Herman and a host of others.

A nudge in the right direction to get you started...If you haven't done so already, Google "Vintage Double Hose". Before his passing, Bryan Pennington was kind enough to share a wealth of information. Scroll down to the bottom of the home page and click on "Manuals & Catalogs". Go to the Scubapro Schematics folder. The big ticket item is Pete Wolfinger's "Scubapro Technical Service Manual". Also, in the 1st Stage folder you will find all the service manuals and schematics you'll need to play with the MK-10 (a few attached here). As an aside, Pete Wolfinger also has a book in print "Regulator Savvy" available at Scuba Tools.Com (Much more into the theory and highly recommended).

Vance Harlow's book "SCUBA Regulator Maintenance and Repair" (no longer in print) is another great source of information. This source of info tends to be much more specific in regards to the How to / DIY approach. If you google, "Vance Harlow Regulator Repair" and scroll down to you find "Deeperblue.com", click on that site and then look for the post by "Happy Diver". The only thing you need now is a cold beer and a comfortable chair.

Sourcing "Scubapro" parts is one of the bigger challenges. O-Rings can be obtained from the O-Ring Store, McMaster Carr, Scuba Gaskets, Orings and More (see attachment for cross reference). I've sourced HP seats from Ebay and Scuba Gaskets (not cheap...but available).

If you choose to go this route, get yourself the basic tools (IP gauge, Scubapro Multi tool, threaded dowel for 1st Stage, Piston bullet, O-ring installer tool for MK5/MK10).

Most importantly...Enjoy the "free" milk, have fun & "Don't shoot your eye out"

All the best,
Mike

 

[Timmyjane]

Thank you @Bloody Knuckles.
The the initial thought was to save a few bucks. Seems like that is not going to happen. Ha.

Since starting down the self repair hole I have acquired all the necessary tools or made them myself by modeling and 3d printing the necessary tools. I have set up my IP gauge and Magnehelic. I was fortunate enough that a SB member sent me both of the regulator books. ( I followed your directions and found the post by Happy Diver.) I have started reading them but haven't finished one yet. Most of my research has been on SB as well as watching Bryan's repair videos on YouTube multiple times. I stumbled across his library early in my research and have printed and laminated several of the documents for my reference.

One of his tips was to use the schematic and lay each part over the diagram as you took it our of the regulator. I thought that was a good idea for a noobie. Using the Scubapro O-Ring thread and the VDH documents I placed an order with orings.com for about 750 o-rings. Probably overkill. lol . 2 other members have supplied me with some original SP kits for the MK10 as my G250s to get me started with the first builds. I thought it best to start with the actual kits and then make any future repairs with my sourced o-rings.

Anyway I feel like I am off to a good start and have found a lot of support for the projects on SB from the great members here.

 

[Bloody Knuckles]

Thank you @Bloody Knuckles.
The the initial thought was to save a few bucks. Seems like that is not going to happen. Ha.

Since starting down the self repair hole I have acquired all the necessary tools or made them myself by modeling and 3d printing the necessary tools. I have set up my IP gauge and Magnehelic. I was fortunate enough that a SB member sent me both of the regulator books. ( I followed your directions and found the post by Happy Diver.) I have started reading them but haven't finished one yet. Most of my research has been on SB as well as watching Bryan's repair videos on YouTube multiple times. I stumbled across his library early in my research and have printed and laminated several of the documents for my reference.

One of his tips was to use the schematic and lay each part over the diagram as you took it our of the regulator. I thought that was a good idea for a noobie. Using the Scubapro O-Ring thread and the VDH documents I placed an order with orings.com for about 750 o-rings. Probably overkill. lol . 2 other members have supplied me with some original SP kits for the MK10 as my G250s to get me started with the first builds. I thought it best to start with the actual kits and then make any future repairs with my sourced o-rings.

Anyway I feel like I am off to a good start and have found a lot of support for the projects on SB from the great members here.

Well you've definitely hit the ground running... Me, I tend to start out slow and ease off. As an aside, another great source of information (if you haven't stumbled across it already) is Rob Singler's "Regulator Geeks" series available on YouTube (there are currently 4 episodes available... Great stuff). You mentioned above that your MK10's are paired up with G-250's. In Regulator Geeks 2: Rob discusses in great detail the lineage and evolution of Scubapro's air barrel design. Again, highly recommended. I'm quite confident Rob has forgotten more about regulator repair & maintenance then the majority of us will ever know. If required subject to your MK-10 rebuilds, he also has a very informative posting here on SB under the heading of "How to Restore a Knife Edge Piston". Also, I HIGHLY recommend you get yourself some Micromesh. The sampler packet available on Ebay will meet your needs nicely. I find a light polishing using mild finger pressures on the piston stem and the piston head o-ring interface area goes a long way in eliminating any stuttering. I use 4000, 6000, and finish with 8000...Just a minute or so with each grit works nicely. The USB Micro scope is also quite the handy tool (cheap money and a ton of fun to play with once you get the hang of it). The attached pic is an image of a piston o-ring gland shelf area. This is the kind of damage that can be inflicted by a ham fisted steel-pic wielding "tech" Fortunately the "tech" attacked the o-ring from the ambient chamber side of the gland. Essentially this is a non-sealing surface. If the damage was inflicted on the opposite shelf of the gland this would have been the makings of a paper weight.

Again, good luck and let us know how you make out.