From yesterday, the cream stout that I was writing about:
Q: I have keg leak problems. I installed a new main lid o-ring, but I still can't get a good seal. I think I have some leakage through the pressure relief valves as well. I should replace them, but they are rather expensive.
A: A few ideas about leaky kegs. This is based on my experience working with about 30 of them, both ball-lock and pin-lock.
First of all, I'm surprised about your problem with leaky pressure relief valves. I've only had to repair one relief valve and that was because the little rubber stopper came unglued from the spring. A drop of superglue fixed it easily. I suggest you just take the reliefs out of the lid and really clean the lids and reliefs with an overnight soak in some TSP [Trisodium Phosphate available at your paint store] followed by much rinsing. When you reinstall them, use a little Petro-Gel or Silicone Grease and I expect you'll be fine.
As far as lids leaking, you should check both the lid and the keg for little dents. You can bang those out with a hammer. After checking and repairing any dents, you can permanently fix the problem by bending in the little legs of the clamp. This will be difficult and you'll probably need a vise and big pliers. A quick temporary solution is to put dimes under the feet and that will tighten the lid. You don't need much added thickness to make the lid seal tighter.
Another problem that I've seen is that the popit leaks. Usually the same solution as the relief valve. Take apart and thoroughly soak. Sometimes either there is a small nick in the rubber seal or where it seats inside the post. If that's the case, you'll have to buy a new one. I've also seen problems with the popits either being too loose so they don't seal well or too tight so that it's difficult to install the QD's. If that's your problem, take the disassembled post to your HBS and try the four different types of popits in the post. Over the years, your corny has been repaired many times and probably the wrong popit was installed and is causing the problem.
And lastly, the o-rings. Change all 5 of them regularly. They are cheap insurance against problems. I buy them by the hundreds from http://www.mcmaster.com. And when you have the keg disassembled, really check it carefully because sometimes double o-rings have been installed by mistake. Or parts of them still remain inside the post. Make sure everything is removed and clean before reassembling.
McMaster Numbers and Prices on January 2005
Dip Tube O-Rings [I use the same ones for both pin- and ball-lock kegs]
9452K172 BunaN #109 Pkg 100/$2.24
Post O-Rings
9452K23 BunaN #111 Pkg 100/$2.77
Lid O-Rings
9452K218 BunaN #417 Pkg 10/$12.50
Added later: I found this Canadian firm that sells replacement parts for all the various models of SS kegs. They have parts for some old kegs that I haven't seen sold here in the States.
http://www.simgo.com/replacem.htm