Scubapro G-250 Troubleshooting

[ams511]

A little trick in checking parts is to put the poppet and balance chamber together without the spring with it sitting with the seat of a very smooth surface (like glass). If you lightly push the balance chamber down, the trapped air should make it rebound. This will verify seat, poppet, o-rings, lube, and balance chamber health.

I did check it out and yes it pops back. The orifice did look good visually and passed the fingernail test. Under the loupe I do see some black marks on the face. I will clean it again and try using an eraser to clean the edge.

I am fairly certain I installed the poppet correctly. The is the third old SP I did and the other two worked perfectly. I did check the poppet against a new one and I see no defects. The rivet seat is a bit different than the SP one. I am using Beuchat seats. The head is a bit thicker.

Speaking of the poppet, It could be the lever is off. I don't think it is of the newest design.

I did compare the old spring to a new one. The problem is I am unsure if the new spring is actually an SP part or aftermarket. That said, the new spring is longer than the old one.

 

[Couv]

I KNOW you checked the IP from the first stage.....therefore I won't even mention it.

Most probable cause goes pretty much in this order:
Seat- when tuning, remember to press the purge button regardless of what the manual says.
Orifice-check it with your fingernail, good light, high magnification, rub a Q-tip around the edge and see if it catches any cotton fibers. Is there a good o-ring on the orifice?
Lever-is the lever height correct?
Spring-yes, it could be weak-even a new one.
Poppet-are the feet worn?
Air barrel notches worn.

In post #6 @rhwestfall gave a good tutorial on how to check the health of the balance chamber components. If the o-rings were compromised you would see tiny bubbles coming from the mouthpiece. Finally, stop doing an underhaul. Make sure the air barrel is clean and run a pencil eraser around the orifice and over the seat to remove any contaminants.

 

[rhwestfall]

Would the thickness of the seat them be an issue? With a thicker seat, the overall length of the system is longer, and to compensate, the orifice would then have to be in a different location, making the lever in the wrong height, or the spring in a different compression, impacting the seating...

Or am I way out in left field????

I know i ran into a few different height orifices on my G250 variants, and it seemed to cause issues....

Always wanting to hear thoughts.

 

[ams511]

I KNOW you checked the IP from the first stage.....therefore I won't even mention it.

Most probable cause goes pretty much in this order:
Seat- when tuning, remember to press the purge button regardless of what the manual says.
Orifice-check it with your fingernail, good light, high magnification, rub a Q-tip around the edge and see if it catches any cotton fibers. Is there a good o-ring on the orifice?
Lever-is the lever height correct?
Spring-yes, it could be weak-even a new one.
Poppet-are the feet worn?
Air barrel notches worn.

In post #6 @rhwestfall gave a good tutorial on how to check the health of the balance chamber components. If the o-rings were compromised you would see tiny bubbles coming from the mouthpiece. Finally, stop doing an underhaul. Make sure the air barrel is clean and run a pencil eraser around the orifice and over the seat to remove any contaminants.

Thanks for the reply.

The IP is double-checked because I have an IP gauge on the BC hose and one on the inline adjuster. Both register 140. A bit high but within specs.

I followed the directions given in the VDH video. I set the lever height a bit low and then rotated counter clockwise to bring the lever up to the proper height. I did not purge the reg when doing this. I actually wondered about this because in the past using the screwdriver method I always purged before adjusting. This is the first time I used the inline adjuster.

As I mentioned in a previous post the spring looks a bit short compared to a new one. Both the lever and barrel notches look good. The poppet feet look good also.

As far as the underhaul goes. The only thing that was not changed was the two o-rings on the poppet. I did not change them because they looked good and I did not have the correct size. The two o-rings on the airbarrel I did not change but Scubapro does not call for them to be changed out.

 

[ams511]

Would the thickness of the seat them be an issue? With a thicker seat, the overall length of the system is longer, and to compensate, the orifice would then have to be in a different location, making the lever in the wrong height, or the spring in a different compression, impacting the seating...

Or am I way out in left field????

I know i ran into a few different height orifices on my G250 variants, and it seemed to cause issues....

Always wanting to hear thoughts.

Bob, I understand what you are saying, however the orfice is adjustable and should be able to compensate for the difference in thickness. However you may be on to something. When looking at the seat I notice that it does not sit flush with the poppet. There is gap between the back of the rivet and the poppet. The Beuchat seats are not that different from the Trident ones. I have used the Beuchat ones on my Apeks TX seconds without a problem.

 

[buddhasummer]

To be honest when I was on my G250 bent I got so frustrated trying to figure out what was going on with some of them I just began replacing with OEM parts the orifice, spring, seat, new style poppets and the long crown X type balance chambers, after I started doing that as a matter if course I never had another issue with any of them. I was lucky though as had easy access to parts.

 

[rhwestfall]

add to that trying to update from an old poppet/lever, and it just gets "fun"....

 

[ams511]

To be honest when I was on my G250 bent I got so frustrated trying to figure out what was going on with some of them I just began replacing with OEM parts the orifice, spring, seat, new style poppets and the long crown X type balance chambers, after I started doing that as a matter if course I never had another issue with any of them. I was lucky though as had easy access to parts.

If i was going to keep this second stage then I would just replace all the parts. However, this one is surplus and will wind up on eBay, so I don't want to dump a lot of parts into it. If it is clean and it works then I feel ok selling it. I have most of the parts except for the levers and orifice.

I think there was something wrong with it before I received it. The C-clip was missing on it so maybe someone tried to fix it. It had some corrosion on the inside and adjuster was packed with lube.

 

[ams511]

add to that trying to update from an old poppet/lever, and it just gets "fun"....

It has the newest s-wing poppet, but I thought the lever was only an issue on the 109/156 not the G-250.

 

[ams511]

Thanks for all your help. I replaced the spring and seat and no luck. I put it away for now and will play with it latter.