Keg Post Leaking Where it Joins the Keg Body?

[donovanlambright]

I am trying to eliminate a persistent CO2 leak on a ball lock keg that I've had for years. It is leaking at the bottom of the liquid post. I tried replacing the o-ring on the dip tube a couple of times. When that didn't work, I put two o-rings on. Both times, I applied keg lube liberally. But no go.

I know it sounds crazy but the soapy water test makes it look like it's leaking where the intake for the dip tube meets the body of the keg, rather than under the post. I've never heard of such a thing and some google searches don't show anyone else describing it. But I'm wondering if it's possible for the keg body to crack where the intake is joined. Have any of you experienced this? Even if that is not the cause, I'm still stuck with a leak I can't seem to eliminate. I've attached a video showing the leak bubbling in the soapy water to illustrate. Thanks in advance for any help; I'm losing my mind over this.

 

[day_trippr]

A side view of that bubbling would help pin down the location, but note if that keg rubber is butting up to the post there could be a pin hole leak somewhere else on the keg top that's just finding its way out through the hole for the post. That's been seen here before - as well as posts that lost their weld...

 

[Agent]

Without seeing the video, I can tell you that you are probably not crazy. There are numerous variants in keg post dimensions. It's possible for a slightly different style post to bottom out on the keg top before sealing the diptube/gasket. If such were aggressively tightened, it could crack the weld, causing a slow leak.

 

[Whisky River]

Without seeing the video, I can tell you that you are probably not crazy. There are numerous variants in keg post dimensions. It's possible for a slightly different style post to bottom out on the keg top before sealing the diptube/gasket. If such were aggressively tightened, it could crack the weld, causing a slow leak.

That’s what I would suspect as well. It kind of looks like the post has been replaced with a universal ball lock post at some point. A number of suppliers use different dimensions, especially the internal height dimension between the bottom and the sealing surface, leading some posts to bottom out on the threads before the sealing surface contacts the top of the dip tube. Do you have a different set of posts you could swap out as a test?

 

[donovanlambright]

I tried a 5/8" post (the original was 11/16") and it still leaked. I'm transferring the beer to another keg. Will decide what to do with this one later.

I noticed that pressing down on the post reduced the rate of leakage. Seems to support the idea of a crack or failed weld.

 

[tracer bullet]

Any chance the post is bottomed out, and can't go tighter? I've had a few leak a little bit right there, and finally realized it's because the post bottomed out and couldn't go tighter, thus it didn't actually squish the o-ring. When I changed to a new post that was physically shorter, it was fine.

The post should seal with the o-ring that's on the dip tube. If it's not bottoming out, then hand tight is actually enough. You can easily be fooled into thinking it's tight, but it's actually bottomed out and so it simply can't go any farther. But the gasket is not squished at all, or not enough anyhow.

 

[day_trippr]

I think doubling the dip tube O-rings would have covered at least some mismatch in post vs riser heights.

fwiw, if that keg doesn't have beer in it, make sure the lid is tight, remove the beer post from the threaded riser, attach a gas supply to the gas post, put some pressure on it (20 psi will work) while you plug the open out riser with a thumb, while looking for a leak around the base of the riser. That'll eliminate the post entirely...

Cheers!

 

[tracer bullet]

I think doubling the dip tube O-rings would have covered at least some mismatch in post vs riser heights.

If they expanded outwards far enough, perhaps. Height is covered, but maybe not squish factor. And though there's double the height, and you'd think they'd squish out, they are each taking half of an incomplete clamping force and still might not.

 

[Bobby_M]

It's hard to see for sure but it looks like it's coming from where the threaded base of the post is welded to the keg body. In other words, nothing to do with any gaskets. You might want to cut some of that rubber away from the post so you can see what's going on.

 

[day_trippr]

^that's what I've been thinking^
Testing without the post should answer that definitively.
And for anyone wondering, there's no magic to stopping ~20 psi with a thumb. Bt/dt

Cheers!

 

[eliastheodosis]

^that's what I've been thinking^
Testing without the post should answer that definitively.
And for anyone wondering, there's no magic to stopping ~20 psi with a thumb. Bt/dt

Cheers!

This seems like the way. And, yeah, 20 PSI...think about the math. I think most of us here should be able to manage it