G250? Worth servicing?

[rhwestfall]

I think the orifices on my 109s and G250s are all chromed brass, not stainless steel. I guess some of them could be stainless, but I know I've had a few with the chrome pitted.

Yes, they were originally that way, but at some point, they went to SS. I don't know when. Then they changed again to the plastic ones in the recent past.

 

[redacted]

There was also some gold plated brass in the 11-109-109 family.

 

[Doby45]

I had gotten a G250 off the used market, that had "official" serviced labels on it (the place used a custom hose protector with the shop name, and date of service). I quickly serviced it, and just couldn't get it to work.... As I looked at my parts supply for options, it dawned on me that the only times I had seen 109/156, g250 & G250v orifices, they were stainless steel or plastic, and this one wasn't.... It was then that I compared it to a known one, and SURPRISE!!!!!, it is shorter.

As I said, I don't have my schematics handy, but the only other "brass" orifice I have seen [edit - I thought I have seen] was in a G200/G200b.

Anyhow, here are the two:

Proper height:


View attachment 378703


Problem height:

View attachment 378704

YMMV.

I would say one way you could tell without actually measuring is if you look at the "correct" one in the picture above you see a bit of space between the threads and the start of seating surface chamfer. You do not see that on the brass one. The threading goes right to the edge of the chamfer. Does that make sense?

 

[rhwestfall]

There was also some gold plated brass in the 11-109-109 family.

apparently so as the one I had seen before is in fact in a G200/G200b (found it last night).... However, I'm not tearing it down or my G250HP or S600 to see what the measurements are for reference.... that will have to wait...

I would say one way you could tell without actually measuring is if you look at the "correct" one in the picture above you see a bit of space between the threads and the start of seating surface chamfer. You do not see that on the brass one. The threading goes right to the edge of the chamfer. Does that make sense?

I'd bet if I rotated that orifice, it would appear the same as to the threads....

 

[NotSure]

Sorry, yet another question, what size Allen key/hex is required to remove exhaust T? We are metric but I'm guessing it's not?

On my G250 Graphite you need a 3/32" allen key.

I think the orifices on my 109s and G250s are all chromed brass, not stainless steel. I guess some of them could be stainless, but I know I've had a few with the chrome pitted.

I have seen a stainless orifice in a G250 V and a G260 but all brass in earlier regs.

I had gotten a G250 off the used market, that had "official" serviced labels on it (the place used a custom hose protector with the shop name, and date of service). I quickly serviced it, and just couldn't get it to work.... As I looked at my parts supply for options, it dawned on me that the only times I had seen 109/156, g250 & G250v orifices, they were stainless steel or plastic, and this one wasn't.... It was then that I compared it to a known one, and SURPRISE!!!!!, it is shorter.
YMMV.

I don't understand why a slightly shorter orifice would make any difference unless it is so short that it bottoms out before applying enough pressure to the seat.

 

[rhwestfall]

I don't understand why a slightly shorter orifice would make any difference unless it is so short that it bottoms out before applying enough pressure to the seat.

likely, and then you can't get the proper lever height to get it operating...

 

[buddhasummer]

Both the orifices on my regs look to be in bad shape, certainly not razors edge, under a magnifying glass they look uneven and pitted. How perfect do they need to be? I've reached out to VDH re plastic replacement orifices but have yet to get a reply. Does anyone know another source?

I'm about to go into a LDS to see what parts are still available over here, I'm quietly hopeful given the number of them I still see in service.

Just picked up a third G250 rather cheaply that I can a) check the orifice to see if it's the same as the two I currently have and b) canabolise it if need be. Cheers

 

[buddhasummer]

And yes, NotSure, you are indeed correct it's a 3/32, thanks for the info.

 

[NotSure]

Any Scubapro dealer should have the orifices you need. They are still used in many of the current models. Try to get stainless steel or brass, plastic as last resort.

 

[halocline]

Both the orifices on my regs look to be in bad shape, certainly not razors edge, under a magnifying glass they look uneven and pitted. How perfect do they need to be?

They should not be sharp like a razor or like a piston edge on the MK5/10. If the edge is pitted, that's a problem. You want a nice clean surface to seal against the soft seat with a minimum of pressure. That's how you get maximum performance. The metal orifice has a slightly sharper surface than the plastic ones (at least it feels that way) and I suspect that they are a bit more consistent when they're in good shape.

I have improved some older brass orifices by lap sanding them with micromesh. This is helpful when the chrome has come off in spots on the edge. Basically you take some sort of fine abrasive paper and glue it to a very flat surface, then carefully run the orifice, edge down, over the abrasive until you have a flat, clean edge. You could then take a fine abrasive cone (I use micromesh wrapped around a chopstick or pencil tip) and clean up the inside of the edge. Finally, you can buff the edge with something very fine, like 2400 or 3600 micromesh.

Don't take off too much when lap sanding or you might have trouble with lever height, but you're really only talking about a few thousands of an inch, if that.