classic valve leak chasing -

[mercpb]

I could use a bit of guidance on a classic MM valve, L7/spacer up front ----

• I just put in a full new AGD rebuild kit.
• It’s leaking faintly from frame/ on off area. No leak down barrel. Checked with stethascope
• It stops leaking on trigger pull
• It does shoot but will frequently “response trigger” shoot on trigger release.
• On/off is 750 pin, OEM parts, and I see no wear/scratches in valve chambers

So - leak sounds like bottom half on/off to me. But none of these had any impact....

• Install a different, known working on/off
• On off oring change
• I tried this unit’s on/off (complete w/ orings) in another valve and it works fine
• I tried another back valve for giggles

I'm a bit stuck --- feels like the valve center assembly is only variable left in play?

Any tips/suggestions?

[superman]

what about the fat oring between the valve halves?

[StaticShocked]

I second this. I just installed two rebuild kits (new, from AGD) and that specific oring i could not get to seal completely. Ended up using buna-n rubber orings for the valve halves to make it seal. It was like the OD of the oring while installed was just a few thousands to small (but very close). Both lvl 7 valves, 29000ish and 39000ish serials. The leak was similar to what is described and was intermittent with movement of the valve. Very strange.

[superman]

I have also started using buna orings on the valve halves that don't want to seal.

[mercpb]

what about the fat oring between the valve halves?

Leak is presenting forward of the valve split based on what I hear on stethescope. I've tried 2 new orings (one AGD UR, one BUNA) + 1 other known-working valve back half to no effect.

[nak81783]

The oring between the powertube and front half of the reg? I forget which, if any, of the Classic valves have this oring vs welded vs...

[superman]

most classic valves are laser welded closed. If it is not then maybe it is that one, but i would doubt it.

[nak81783]

superman Welded to secure with an oring still doing the sealing, or welded to seal and secure? If the latter, could the weld have a crack allowing a leak?

I know this is getting out there, but OP has tried most/all of the typical fixes and variable-isolating part swaps.

[superman]

some but not all are threaded on with an oring then welded. I have yet to see one that has a crack in the weld.

[river031403]

Post pics of the on off and orings

[river031403]

And what the velocity at?

[RuleOfSines]

This is my E-Type, but idea may work, you need a really low pressure air source

https://www.youtube.com/watch?v=y5K0oPItqqg

[mercpb]

cool rig and in other news, I need to read up on E-types!

[superman]

I have a cut powertube body that i use to check that.

[mercpb]

thanks for notes gang - AGD runs my local home field, normally I'd just have walked this into Tim's shop but he's in the middle of moving... I'm just going to bring it to him once his dust settles. He advises has rigs to diagnose faulty valves. Will post results