Air Barrel question - corrosion? Scubapro G250V

[aoumi]

Hi,

Overhauling my G250V, and have cleaned out the grease residue etc from the air barrel. But when looking down the air barrel, from the adjustment knob side, their seems to be either a rock hard build-up of gunk or maybe it's corrosion eaten into the barrel, where the o-ring of the adjustment knob is normally positioned in the balance chamber.

Unless this area of imperfection is sorted out and returned back to a smooth surface, the new o-ring on the adjustment knob, when re-installed, isn't going to make a great seal.

I have scrubbed away down there with a firm toothbrush, hot water, and dish washing liquid, but it won't move.

Holding the air barrel up to the sun at just the right angle so that the sunlight hits the area in question, it seems to be a slight green colour like corrosion, and may have eaten into the air barrel in one spot exactly where the o-ring would sit. I was unable to capture the slight green colour under sunlight.

See attached photos....

Does this mean a replacement air-barrel is required due to possible corrosion? Or just a good ride in an ultrasound (which I don't have).

Thanks

 

[northernone]

Excellent photos, from what I can figure, that's a valley not a mountain. Could you tune it so the oring doesn't sit in the imperfection this rebuild and leave it at that? Carefully honing it out seems risky, anyone have success?

 

[Fibonacci]

Hmm... I've had good results removing worse green corrosion (in a Sea Hornet MK5) using 00 bronze wool wrapped around a bamboo chopstick. Try it after soaking for 15 mins in a warmed bath of 50:50 white vinegar and water.
Less aggressive than steel wool or wet'n'dry paper on the thinly plated brass tube... don't want to expose more bare brass for rapid corrosion in that enclosed humid space.
I get mine from Brownells
Bronze Wool - #00 Bronze Wool - Brownells

 

[АлександрД]

I`d removed scratsches and corrosion using Mini drill (like "Dremel") similar with GOXAWEE 220V Power Tools Electric Mini Drill with Flex shaft 160pcs Rotary Tools Accessories For Dremel Drill Tools 3000 4000-in Electric Drills from Tools on Aliexpress.com | Alibaba Group

some days ago I bought another one for my wife for polishing nails USB powered, very light and cute
like that one USB 3 12V Mini Electric drill Hand Drill Motor Hole Saw Aluminum Mini Electric DIY PCB with drill for Wood Plastic Drilling-in Power Tool Sets from Tools on Aliexpress.com | Alibaba Group
In your case it could be more suitable.

Than take felt polishing tip, like Fixmee 13PCS/ Set Wool Nail Felt Polishing Rotary Grinding Tool Burrs Felt Tipped 3mm-in Abrasive Tools from Tools on Aliexpress.com | Alibaba Group
green polishing wax (in our county we have so called GOI paste, chineese analog is https://www.aliexpress.com/w/wholesale-green-polishing-compound.html ) ,
and start to polish!
When finish - clean paste with spirit or any other solvent, than wash details well.

here is one important thing:
when you will polish it, you also can remove chromium layer, and later corrosion could be more strong.
So, you will need to check regulator condition more frequently.

 

[rhwestfall]

A wool disc on a dremel and Flitz metal polish works wonderfully. I have recovered piston walls in first stages using it. If it works in that application, I can't imagine it won't work here. It won't be as aggressive on the chrome as other ideas presented above.