Advice on my first run through of a G250

[Erik Forsberg]

Hi DIY:ers,
Personal background: Have worked as car mechanic, do Arduino stuffs as a hobby, studied masters in vehicle engineering over here; not god-like mechanical skills but above average. Good understanding of how a regulator works.

Ever since I started diving and saw the absolute horrors of both quality and price of services ($200 for singles, $300 for doubles) I have leaned into doing my own servicing, but I don't want to dive into it (badum tisch) on my regulators (Apeks XTX50 and DST). A while ago I found a set of older scubapro regs for $30 at a sale and picked them up in order to have something to practise on so to speak.
Picture of the regs: Garage sale regs


From going over schematics it looks to be a G250 rev D together with an R190 and an Mk10, which seems like a good enough place to start my journey.
My questions for you DIY:ers are:
1) Would I need any special tools apart from the Scubapro nut spanner, C-spanners, the piston bullet, pin spanner for hp seat, piston O-ring tool?
2) If my assumptions are real and the reg is a rev D, it should already have the S-wing poppet. If not, I assume it really should be upgraded? If so, where do I find one. Ebay doesn't seem to have any at all.
3) Should anything else also be upgraded/changed that isn't a part of a service kit? If not on the G250, how about the R190 or the Mk10?
4) Anything else I missed or didn't think about?

Super thank you in advance and this sub-forum is a great read!

 

[blatter]

You definitly need a guage to measure the interstage pressure to make sure regs are working properly, to prevent burst hoses if they aren't and to adjust interstage pressure on diaphram first stages. Soft (plastic) o-ring picks may be useful. An ultrasonic cleaner is very nice to have but not absolutely essential. I got a cheap one and it really makes cleaning much easier and safer for plated brass parts. Some would say you need to be able to measure the inhale resistance for servicing 2nd stages, but I just check that the purge is OK and that they are breathing OK for my own regs. Service manuals are a very good idea and manuals for most regs can be found online. I think it is very important to follow manufacturer service manual procedures. Some regs require specific disassembly and reassembly procedures that may not be apparent to beginners. A really great general reference is Vance Harlow's Scuba Regulator Mainaninance and Repair from Airspeed Press. Entertaining as well as informative, I enjoyed reading it even after many years of servicing my own regulators.

 

[rsingler]

Hi DIY:ers,
From going over schematics it looks to be a G250 rev D together with an R190 and an Mk10, which seems like a good enough place to start my journey.
My questions for you DIY:ers are:
1) Would I need any special tools apart from the Scubapro nut spanner, C-spanners, the piston bullet, pin spanner for hp seat, piston O-ring tool?
2) If my assumptions are real and the reg is a rev D, it should already have the S-wing poppet. If not, I assume it really should be upgraded? If so, where do I find one. Ebay doesn't seem to have any at all.
3) Should anything else also be upgraded/changed that isn't a part of a service kit? If not on the G250, how about the R190 or the Mk10?
4) Anything else I missed or didn't think about?

Super thank you in advance and this sub-forum is a great read!

Re: #1 @blatter is absolutely right about picks. Some brass fine tip pics, and for the Mk10 and regulator hose end o-ring - a double hook pick.
But watch out! The steel double hook pick is the most dangerous tool for a DIY'er. If you score the bottom of an o-ring land, you may acquire an unfixable leak. That applies especially to the HP oring land buried in the Mk10 body. A double hook pick makes extracting an old, dry, stiff oring much easier, but at risk. An IP gauge. Search these threads for multiple DIY gauge instructions. A magnehelic and mouthpiece is Cadillac, but you can do the sink test just as easily. Still, if you get bitten by this bug, PM me. I can sell you one cheap.

Re: #2 PM me. I can sell you an upgrade kit out of my spares.

Re: #3 Search for the "annotated" schematics. They give the oring sizes of ALL the parts not included in the service kit, and yes - you should replace more than is in the kit. Turret orings, for example in the Mk10. Not essential, but orings are so cheap we all replace them all every time.

Re: #4 A hook wrench to unscrew the body of the Mk10 is nice. A BIG right angle needle nose plier that you sand smooth makes a good tool for unscrewing faceplates that seem to be stuck. Wooden dowels are critical. Go to Home Depot for as many sizes as they have, and a hobby shop for the smaller ones. I regularly use 1/8", 3/16", 1/4", 5/16", 3/8" and 1/2" for soft pushers for a variety of regulators. The brass round end tool from Scubatools and others is the right diameter to push out the G250 orifice without damaging the knife edge, or one of those dowels (?3/16"?). Micromesh cloth-backed sandpaper in REALLY fine grit (e.g., 2400 to 8000) from eBay ($18) is essential to restore an old metal G250 orifice, or a Mk10 knife edge. A 1" thin wall shallow socket and a short 3/8" extender to remove the Scubapro yoke bolt. Other manufacturers, other sizes. I'm anal about torque settings, so...a torque wrench. But other guys...not so much.


Welcome to the club!

 

[Erik Forsberg]

You definitly need a guage to measure the interstage pressure to make sure regs are working properly, to prevent burst hoses if they aren't and to adjust interstage pressure on diaphram first stages. Soft (plastic) o-ring picks may be useful. An ultrasonic cleaner is very nice to have but not absolutely essential. I got a cheap one and it really makes cleaning much easier and safer for plated brass parts. Some would say you need to be able to measure the inhale resistance for servicing 2nd stages, but I just check that the purge is OK and that they are breathing OK for my own regs. Service manuals are a very good idea and manuals for most regs can be found online. I think it is very important to follow manufacturer service manual procedures. Some regs require specific disassembly and reassembly procedures that may not be apparent to beginners. A really great general reference is Vance Harlow's Scuba Regulator Mainaninance and Repair from Airspeed Press. Entertaining as well as informative, I enjoyed reading it even after many years of servicing my own regulators.

Super thank you for your answer!
I have Vance Harlow's book already and have read it thoroughly. Great book and great blueprints (and cartoons )
I'm sorry for my badly written post; apparently I left out a ton. I already have the book and o-ring picks and an pressure guage with LP connection. I don't think I'll get a ultrasonic cleaner just yet; gonna wait to see how far I get with just elbow grease and and water/vinegar etc.
I don't have the service manual for my regulators, but I think I'll find them if I just browse around some
Thank you so much for your advice and tips!

Re: #1 @blatter is absolutely right about picks. Some brass fine tip pics, and for the Mk10 and regulator hose end o-ring - a double hook pick.
But watch out! The steel double hook pick is the most dangerous tool for a DIY'er. If you score the bottom of an o-ring land, you may acquire an unfixable leak. That applies especially to the HP oring land buried in the Mk10 body. A double hook pick makes extracting an old, dry, stiff oring much easier, but at risk. An IP gauge. Search these threads for multiple DIY gauge instructions. A magnehelic and mouthpiece is Cadillac, but you can do the sink test just as easily. Still, if you get bitten by this bug, PM me. I can sell you one cheap.

Super! I don't think I dare wander into the lands of steel picks to be honest. A small slip up can cause a lot of damage, and I don't feel confident enough to risk it
Are there not double hook picks available in plastic or brass?

Re: #2 PM me. I can sell you an upgrade kit out of my spares.

You sir, are a gentleman and a scholar! I'll send you a PM right away

Re: #3 Search for the "annotated" schematics. They give the oring sizes of ALL the parts not included in the service kit, and yes - you should replace more than is in the kit. Turret orings, for example in the Mk10. Not essential, but orings are so cheap we all replace them all every time.

Nice! I'll just find a local O-ring supplier here and buy some bulk then and replace all of it. Awesome advice!

Re: #4 A hook wrench to unscrew the body of the Mk10 is nice. A BIG right angle needle nose plier that you sand smooth makes a good tool for unscrewing faceplates that seem to be stuck. Wooden dowels are critical. Go to Home Depot for as many sizes as they have, and a hobby shop for the smaller ones. I regularly use 1/8", 3/16", 1/4", 5/16", 3/8" and 1/2" for soft pushers for a variety of regulators. The brass round end tool from Scubatools and others is the right diameter to push out the G250 orifice without damaging the knife edge, or one of those dowels (?3/16"?). Micromesh cloth-backed sandpaper in REALLY fine grit (e.g., 2400 to 8000) from eBay ($18) is essential to restore an old metal G250 orifice, or a Mk10 knife edge. A 1" thin wall shallow socket and a short 3/8" extender to remove the Scubapro yoke bolt. Other manufacturers, other sizes. I'm anal about torque settings, so...a torque wrench. But other guys...not so much.

Super! You guys are absolutely fantastic for a newbie like myself! Expanding my shopping list a bit after reading your comment

Welcome to the club!

Thank you so much, and glad to be here

 

[Erik Forsberg]

Quick follow up question: Have SB reached any conclusion on what material to use for extra O-rings? Is it EPDM or Buna?

 

[rsingler]

My preference is EPDM, though I can't get that in Shore 90 here. I use Viton for my Shore 90 orings.

But Buna-N has been around forever, and at the cost of shorter longevity and less oxygen tolerance, it works just fine.

But me, I use EPDM and Viton exclusively.

 

[Erik Forsberg]

Thank you yet again!

 

[Scubagaskets]

EPDM O-Rings Archives - Premium O-rings Provider for Scuba Diving
VITON® Scuba O-rings For Nitrox Archives - Premium O-rings Provider for Scuba Diving
Scubapro O-rings Archives - Premium O-rings Provider for Scuba Diving

 

[Couv]

Hi Eric,

Yes, welcome to the Dark Side. @blatter & @rsingler have covered pretty much everything that's important. To find the manuals you need, including the annotated files go to www.vintagedoublehose.com then navigate to the Manuals and Catalog section. For tools like the o-ring insertion tool and 1 inch socket contact @herman who manufactures those items. He also has other tools you may find useful so tell him what you're working on and he'll help you out.

An ultrasonic cleaner is nice to have especially if you have a lot of regs to rebuild, but if you're only servicing a few I suggest elbow grease and a good set of brushes such as found in a gun cleaning kit.

Vintage Double Hose also has a series of helpful videos and sells service kits.

 

[Erik Forsberg]

Hi Eric,

Yes, welcome to the Dark Side. @blatter & @rsingler have covered pretty much everything that's important. To find the manuals you need, including the annotated files go to www.vintagedoublehose.com then navigate to the Manuals and Catalog section. For tools like the o-ring insertion tool and 1 inch socket contact @herman who manufactures those items. He also has other tools you may find useful so tell him what you're working on and he'll help you out.

An ultrasonic cleaner is nice to have especially if you have a lot of regs to rebuild, but if you're only servicing a few I suggest elbow grease and a good set of brushes such as found in a gun cleaning kit.

Vintage Double Hose also has a series of helpful videos and sells service kits.

Thank you so much!

I got my orders in from Herman and VDH already now.
The Dark Side is the best side anyhow!