Tuning eeks! Leaks! (Brocock)

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LMNOP

LMNOP

Member
Jul 7, 2021
409
275
Southern United States
Hi all,

I recently developed leakdown issues with the Concept Lite.

Thanks to the membership here and the tome of knowledge I did the balloon test. After watching AoA's wonderful video on the Contour which is essentially the same as the Concept Lite from the fill tube aspect I removed the check valve and sintered brass filter. I could see quite a bit of black shredded O-Ring debris. The seal looked ok so I cleaned everything, lightly lubricated it with Trident silicone grease, and reassembled it. Not sure how the O-Ring debris got there I don't recall shredding any O-Rings. Only O-Ring in that assembly is white, so maybe the fill probe or a bad foster fitting O-ring.

I filled to 220 bar and re-ran the leak test. The balloon still fills. I called AOA and they graciously, free of charge, sent me a set of check valve O-Rings. Amazing service!

Last night I re-ran the balloon test with it only covering the gauge, not the fill port. The balloon inflated. I am re-running the leak test now after tightening the gauge even more this morning but not what I would consider excessively. A little more force than I would consider normal but not excessive.

My question -- if the gauge is still leaking what are the next steps? New gauge? Same gauge with new washer/seal? Do gauges go bad?

I'm trying to narrow down what could be a two phase problem -- leaking gauge and leaking check valve. Perhaps I've fixed the check valve issue and now introduced the leaking gauge issue. The debris in the check valve body leads me to believe it was certainly suspect to being the initial problem. Thanks for any suggestions!
 
Thanks -- I've actually narrowed down the source using a balloon. I know the gauge is leaking and the dowdy seal was deformed a bit when I removed it to check on the inlet fill check valve o-ring. I've ordered some replacements from Pyramid Air and will replace it then repeat the leak test. If no leaks, I'll call it done. If a leak at the gauge I'll scratch my head a bit. If a leak at the gauge + inlet fill inside the balloon using the balloon test I'll replace the inlet check valve o-ring.

All in all, glad for this community, would not have considered the balloon leak test method but it's just order-of-operations and process of elimination. The leak is so slow it's maybe 20-30 bar a week.

I think I've got it all narrowed down now. Hopefully it's just at the gauge so I don't have to remove the cylinder end assembly again but it wasn't too hard.
 
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Replaced the dowdy seal on the gauge. Sadly having left the cylinder at 1 bar for 1.5 days now results in air blowing past the regulator. Eeek! Constant leaks, chasing down one, to another. I plan to leave it out in the sun tomorrow before attempting to refill again from 1 bar hoping maybe the heat will expand everything and make it seal to hold pressure which causes expansion. I got it up as far as 150 bar before it was puking air where the cylinder meets the action.

This might be my last Brocock — had a Commander that had a leak and now this Concept Lite. If you see a Classified ad for my LC-110 and Ninja 90 cu-in know I threw the Brocock in the trash and bailed on this PCP addiction :)
 
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Hah! I'm really just kind of dumbfounded, it held at 220 bar and would leak down maybe 10 bar in a week around the gauge. I removed the gauge, it sat empty for a day or two, I reinstalled the gauge with a new dowdy seal. I attempt to fill and it blows air like crazy out of the rear of the cylinder around the action. I've tried cocking it, shooting while filling, etc. I can get it all the way up to 220 bar while I'm shooting and it sounds normal, minus the air blowing out the cylinder. In 2 seconds it's empty again.

Just super odd. Oh well, off to AOA I guess unless someone has ideas. I didn't golden screwdriver anything back there. :)
 
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FIXED! :)

I removed the air cylinder and found a shredded O-Ring. There is a single O-Ring that mounts to the back of the regulator that seals against the action. It does not have double O-Rings like the Compatto there is just a single O-Ring. $00.45 part at the hardware store and I'm back in business.

As an aside, I also ordered a HW100 Bullpup Carbine from AoA today. So big savings all around \o/
 
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To recap:

* Cleaned check-valve inlet O-Ring, had black debris on it.

* Replaced Dowdy seal on the gauge

* Replaced Regulator O-Ring where the rear of the air cylinder meets the action

Thanks again to all who responded! This rifle so far is pretty easy to get apart so that's a good thing -- now that I've learned what I'm doing in the future it will take minimal time and effort.
 
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Hah :) Me too! I really like the Concept Lite but when it comes to o-rings and complex precision devices I get a bit ham-fisted. Thankfully I did not have to "hulk smash" it and all worked out well. What was really nice is how the barrel screw detents align in the same place so removing the barrel, scope mounts, scope thingy-lifty-riser-thing, and cylinder then reassembling it all resulted in no need to rezero the scope. Elevation was spot on and windage was maybe 1" if that. Was worried I'd be off the paper after all was said and done but nope.
 
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