Beer Maverick

How to Fix Leaky Corny Kegs

Nothing is worse than emptying an entire CO2 tank with a leaky keg. I luckily noticed my keg’s leak when I attached a spunding valve which quickly got up to pressure during fermentation in my cornelius keg, but then just as quickly lost it overnight.

The good thing about corny keg leaks is that while they are common enough to have, they are usually very easy to fix. This is especially good as most corny kegs are only available to home brewers after significant wear and tear.

How to Identify the Leak Location

The best way to identify where a leak is happening is to put StarSan in a spray bottle and spritz the lid of the pressurized keg. You will see bubbles starting to form wherever the leak is. Sometimes the leaks are very minor, so you may have to look closely. Don’t forget to check the posts too, however post leaks have been uncommon with me so far. If you do have a leak in a post, make sure you have the correct post thread size.

It is a good idea to do this after each filling. You can never be too careful, and this process only takes a few seconds.

I have seen other places online advocate using a spray bottle filled with soap and water. While this will work just fine, I don’t want to run the chance of it getting into my beer. StarSan doesn’t hurt beer at all, so I’m sticking with it over soap any day.

Gasket Grease

Most lids will leak slowly if the gaskets aren’t lubed up with grease. You don’t need much, just a thin film on the top and bottom of the gasket should suffice. If you find yourself adding more and more, stop. More than likely there is a different problem, which we get into below.

I have a tube of silicone faucet grease that I use, but I’ve used Vaseline Petroleum Jelly in a pinch before. If you use Vaseline, just double check that it is the unscented version and is 100% pure.

Reseat the Lid

If your leak ends up being around the lid – which is most likely – then try to first reseat the lid. You can do this by grabbing a hold of the lid handle and twisting or turning it on under pressure. Add a quick spray of StarSan on top and you’ll see bubbles stop or move to different areas around the lid as it is turned. If the bubbles don’t go away after turning the lid, the opening may have a dent.

Adjusting the location of the lid – however slightly – usually fixes most leaks in my experience.

Note: In the video above, I used one hand because the other was doing the recording on my phone. The lids moves much easier if you use both hands to turn it.

Check for Dings

If reseating the lid didn’t work, then more than likely you have a dent in your keg’s opening. I was able to find my dent by rubbing my fingers on the underside of the opening like shown in the video above. The dent was very slight, so be mindful that it can be tiny. To be honest, I didn’t even see the dent until I had felt it and looked closer.

If you find a dent, don’t worry – it is fixable.

How to Fix Dents Around the Lid

Once I found the dent, I needed to pop it back out. Most dents are “in” or “down”, which means that you need to apply pressure from the underside of the opening to pop it back up into place. The best way I found to fix these types of dents is with the rounded end of a socket handle or pipe.

Place the socket handle or a pipe directly under the dent. Then lightly tap the top of the socket (or pipe) with a rubber mallet to gently bend that metal back up. I tried to do this with my hand, but I felt much more controlled with a mallet. Go easy! It doesn’t take much effort to bend it back into place. It is always best to do a little at a time rather than hit it too hard and make an even bigger dent by accident.

If the dent is “out” or “up”, then you will want to find a small chunk of wood or something and gently tap the dent back down with a rubber mallet or hammer. Same process here – small taps, and go easy. You don’t want to hit it too hard and mangle the heck out of it.

Get New Silicone Rings

If your lid is still leaking and you’ve found no dents, then you may just need new o-ring gaskets. Gaskets are easy to replace, but they last a while, so unless they are old or dry-rotted, this should be your last resort. The gaskets are universal, so it shouldn’t matter what brand your keg is, or if it is ball or pin lock. Find a good set on Amazon or at your LHBS, and replace them.

If you happen to have a dent that you cannot get fixed, and the leak simply will not go away, try to get an oversized gasket. Unlike standard lid o-rings which have a .280″ cross-section, an oversized one has a slightly larger .310″ diameter.

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