Rebuilt two classic valves… now both leak from between the body and reg housings.

[pneumagger]

Finally getting around to tuning two old Center Fire valves I rebuilt. Both had old yellow-brown orings and some of the orings were breaking apart in pieces. So I gave both valves a full rebuild kit and Level 10 bolts.

Now when I go to air up I get a leak out of the seam between the valve halves. If I back the velocity adjust out to “zero” there is no leaks… so I know the reg seat is doing its job and cutting off air supply. And as best I can tell no air comes out the rear velocity nut hole or the bottom two “oil” holes… so the reg piston orings and over pressure vent appears to be fine.

It appears to be coming out of the actual seam where the two valve halves screw together. That big -116 oring must not be mushing into the gap properly and sealing or something. But this is happening on TWO rebuilds using fresh oring kits. Seems improbable. I’m thinking of just trying a softer buna or viton -116 oring there and seeing if that cures it. It’s a static oring so buna/poly/viton/etc. and durometer shouldn’t matter too much. No?


Here’s where it gets weird… I have a third classic style MiniMag valve that was in much fresher condition. It didn’t get a full rebuild. I just tossed a new reg seat and power tube tip orings in it and called it good. It airs up fine. If I put the centerfire reg bodies on the Minimag front valve half… it airs up fine with no leaks.

[RhoXi]

IIRC, I remember hearing the valve half orings orings from AGD are or were slightly out of spec or some such and I think others have had the same issue. I know mine will leak if I have the halfs tightened all of the way but it'll stop if I back them out a touch and this is with the AGD rebuild kit. I say it can't hurt to try a different oring.

[Maxwell]

I had the same problem with a factory rebuild kit, swapped for a 70 Duro Buna and I was good to go. I'm just your average idiot so I can't speak to whether that's a good idea or not, but it worked.

[pneumagger]

IIRC, I remember hearing the valve half orings orings from AGD are or were slightly out of spec or some such and I think others have had the same issue. I know mine will leak if I have the halfs tightened all of the way but it'll stop if I back them out a touch and this is with the AGD rebuild kit. I say it can't hurt to try a different oring.

This was my suspicion based on swapping a bunch parts and stuff around; the only thing that was commonly bad between everything were the two brand new thick O-rings from the rebuild kit. Just seemed really odd to me two brand new factory parts were to blame.

I suppose I could just try some sort of oil that might smell them a little bit, but I don’t really want that oil to get everywhere else either either so I’ll just grab a pair of new O-rings from McMaster

[wthomas333]

I have had several valves like that over the years, never seemed to seal well or sometimes not at all with the AGD orings. I started using a metric oring that was just slightly fatter than the 116 size orings AGD sells and haven’t ever had a problem again. I believe they were 3mm wide x 18mm ID. 116 orings are approximately 2.6mm x 18.7mm.

[Calvin]

I had the same problem with a factory rebuild kit, swapped for a 70 Duro Buna

Same here. I purchased a bunch of urethane from airgundesigns.shop late last year. They all got pushed into the threads and received a small cut about 1/32" long right as you got the marks to line up. I got some buna orings in the same size and they sealed right up. I'm guessing a slightly mis-sized batch of orings.

[superman]

use buna 116 orings

[pneumagger]

use buna 116 orings

Yeah, I’m ordering some slightly softer 70A polyurethane -116 from McMaster.
Part Number 9558K29 (corrected)

The pressure should be able to push the softer material into the gap more easily, it has decently low temp performance and most importantly plays nice with the synthetic mineral oils we like to use.

I would’ve liked to tried a 18x3mm O-ring, but they didn’t have that metric in polyurethane.

[FredMnkyDad10]

Can you double check/confirm the part number. I got something different

[pneumagger]

Whoops… that was some rod for making on/off pins I also bought.

The -116 orings were 9558K29

[pneumagger]

Update: picked up the 70A durometer -116 urethane orings from McMaster… that solved the issue. I got a bag of orings so if anybody else has this issue, PM me and I can get you some

Both classics annd both RTs are shooting decently.

Just have to chrony them and maybe fine tune the Level 10 a bit… I dunno… I just put the red spring, an carrier that slid softly/smoothly and two shims in all of them and called it good - LOL.

although one of the classics seems to want to vent out the back hole right around the point the Level 10 bolt (with red spring) starts to go forward without chuffing. Might have to pull the reg piston and work on it.