I have a very minor gas leak/seepage from the area where the solder is on the gas tank bung fitting that connects to the sediment bowl on my 24 touring. There is no leakage from the sediment bowl itself, the valve or the threaded connections going in or out.
I would like to smear some type of sealer around that area to stop the seepage of gas. I do not want to re-solder or remove the tank from the car. To-date I have been using bar soap but am getting tired of doing that. Any suggestions?
Buy a new tank?
I had a gas tank on a Taylorcraft that had a similar leak, bearing in mind, the gas tank on a Taylorcraft is in the cockpit right in front of the pilot and over his legs. I was told to fix it with a layer of JB weld, and that was in 1991, that repair is still holding. Bearing in mind, it is a major job to remove and refit a gas tank in an airplane. I had a bit of difficulty getting the JB weld to not drip, and that was solved with a bit of brass mesh, like normal window screening. It would be easy to remove the tank from the car so you could invert it to avoid the dripping problem. Or you could spend a couple hundred dollars on a new tank, or find someone who will solder yours, remembering that once you use JB weld on the tank, it is very difficult to go the solder route.
Check that the tank has not rotted out at the collar. If it is OK use large copper soldering irons to sweat the collar off,
clean and resolder. My '23 did this too and is now leak free since I resoldered the 90 year old joint.
If you can lay up the car for several days I highly recommend Loc-Tite Wicking Sealer. Carquest sells the same stuff but they call it "Thread Locker".....used for locking nuts and such AFTER they have been tightened.
I had a leaky steering column support bracket on my '29 Model A. It's riveted to the gas tank and soldered to seal it.
Over many years of shocks the solder joints crack and they seep gasoline.
I ran the tank nearly empty then backed onto a pair of car ramps, sprayed the joint with brake cleaner, blew out the cracks as well as possible and over a few days applied the wicking sealant all around the affected area. I applied it using my jackknife blade tip with only a drop of sealant at a time to get the stuff where it belonged. As long as the cracks continued to wick in the sealant I kept at it for maybe a week and then gave it a 2-3 more days to cure.
The result was problem solved!.......
I've found that modern gasoline w/ethanol eats JB weld.
If you can get a big enough copper soldering iron, you can clean up the metal and solder it. I fixed a leak on a Dodge tank that way. Do not use a torch or any other direct heat source on a gas tank! Do not arc weld. Anything that hot will cause an explosion, but a soldering iron works.
J&B quick will not hold up long. The parts stores now carry a putty for that purpose, the best way is as Norman says and use a large copper iron. If you are good you can do it on your back with gas out and jacked up on one side to keep what remains from being drawn out by the heat. I'm that good:-) KB