CO2 leaking from bottom of gas in post

I recently purchased some used corny kegs from eBay and reconditioned them. Now, one of the kegs is leaking from the bottom of the gas-in post, and I don't know what to do.

They arrived holding pressure--they all had some really gross soda syrup in the bottom and bled off a lot of nauseating-smelling gas. I cleaned the kegs with PBW and replaced all the O-rings with new ones from Brewmaster's Warehouse, and I also keg lubed them.

Today, I was ready to keg my first beer, so I filled one of the kegs with Star-San, took off the posts to soak them in Star-San, then re-assembled the keg. When putting the lid on under 10psi, bubbles started appearing at the base of the gas post. Uh oh.

I reseated the post--no luck. I added more keg lube--no luck. I got a post and dip tube from another keg--still bubbles.

So, what can I do now? Is this keg ruined?

Interesting problem that I haven't experienced. Both posts seal by virtue of the dip tube o-ring expanding under the dip tube flange, but you swapped those already. Can you swap the leaky gas post with one from another keg to at least prove there's something different about the leaky post?

Cheers!

Poppet valve?

Leaky poppets are pretty obvious, and leak from the top of the post, not the bottom...

Cheers!

It's more than likely the o-ring under the gas in dip-tube. That ring seals to the inside bore of the actual post.

Unfortunately, I tried both the post and the dip tube from another keg with no success--it still leaks from underneath the post. I don't think it's the poppet, or at least it isn't leaking from the top, so I don't suspect the poppet. I also tried adding an absurd amount of keg lube, which made a mess but didn't stop the leak. I'll see if I can find another O-ring to swap in.

What size thread does your pin lock keg have? I have some 19/32-18 pin lock posts that I'm not going to use and I can send them to you free of charge. If it fixes the problem you know you have a bad post as these have all been perfect. The rest of the posts can just be spare parts for you to use as you see fit.

Send me a PM.

Still no luck. I tried a brand new O-ring on the leaking post without success. Then, just to try everything, I switched the poppets from the in and out posts on the keg. The in post still blows bubbles when I pour Star-San around the edge of the post.

Any thoughts on where the leak could be coming from at this point? Is it possible that the weld where the post attaches has broken? Warped threads?

I realize you aren't supposed to use teflon tape on a keg, but I might see if I can get some tomorrow. It can't hurt, I suppose...

suorangeguy, thanks so much for your offer--that's very generous of you. Unfortunately, these are ball lock posts. I don't know much about keg anatomy, but I assume I can't mix and match?

sorry. i skimmed the posts and thought you were talking pin lock. don't know why.

Have you tried switching the gas in post to another keg? Another thing I have done in the past is to place two orings on the gas in dip tube than tightening the post as much as possible.

Hmm, suorangeguy gave me a in interesting thought with the mention of thread sizes. I switched both the posts and the dip tubes to opposite sides, since the threads are identical on this keg. The leak happened in the same spot on the keg body, even though the opposite post and dip tube were in its place. I guess this means the leak is in the body of the keg. That stinks--I assume there's nothing to be done at this point?

Sounds like you have the worst case scenario on your hands then. Inspect it closely for damage and hopefully one of your friends is a welder! Damn kegs are worth too much to just toss anymore.

You'll have to inspect the threaded riser and its weld to the keg body to make sure the problem is in the weld and not a cracked riser. If it's the weld, you can fill any voids with silver solder pretty easily. Otoh, replacing or repairing a riser would be a lot trickier...

Cheers!

Before you go welding stuff, have you tried using 2 o-rings on the the dip tube? I received some used kegs like that a while back, and that's what needs to be done to keep it from leaking.

MC

No dice with two dip tube o-rings either, unfortunately. I wish there was some easier way to pinpoint where exactly the leak was coming from. It's somewhere underneath the post, and it's always on the same side--if I swivel the dip tube 180 degrees, the bubbles don't rotate 180 degrees with it. I might try scraping off the rubber around the post tomorrow to see what's going on underneath.

day_trippr, I think you have it. I finally got a Cub Scout knife out and whittled away all the black rubber around the post. It looks like the leak is where the threaded riser meets the keg body.

So, any advice on how to repair this? I don't have welding experience, nor do I have any friends with welding equipment. I do own a soldering iron, and I'm willing to cover it like a friggin mummy's tomb in solder if I think it will actually stick to the keg. I'm a little worried about making some superficial repair, though, if the solder blob might just crack off next time I torque the post. Do I need a torch to make this repair? Can I just use the same flux as for wires to prep the surface? I suppose if I have to ask these questions, I probably am not equipped to make this repair.

If I take it to a welding shop, how much might a repair like this cost? As much as another used keg?

I expect you have a minor breach in the weld fillet between riser and keg body. It could have been an imperfection in the weld, or the weld may have been overstressed by abuse (by a previous owner, of course).

Either way, there's an excellent chance you could repair the void using silver solder with a household propane torch and the appropriate flux. If you take a look at an excellent sticky thread on soldering stainless steel you'll be armed with everything you need to know. If after investing fifteen minutes you don't feel confident as well, take the keg to someone that can TIG weld stainless, show them the weld line, and have them lay down some filler.

Don't go for epoxy, silicone, JB Weld, etc. Fix it right, it won't be hard or expensive. And with serviceable kegs hitting $70 around here now, it's worth fixing right...

Cheers!