While the JB-weld may appear to be sealing in operation the pipe wall will change dimension from thermal expansion while the topical sealer does not. This then opens up minute cracks between the sealant and the pipe or fitting, resulting in another leak. The only sure way to repair a joint that was not glued properly is to cut it out and
Cut the pipe at the nail hole. If you have enough room to flex down one side, slather on the cement and quikly slide the repair coupling all the way onto one side of the pipe. Quickly align the ends of the cut pipe and slide the coupling back over the joint. Working by myself, that is where I get the starved glue joint, on the second piece of pipe.4. Replace the cracked toilet tank. To fix a cracked toilet tank causing the pipe to leak, you will need to remove the old tank and install a new one. The first step is to shut off the water supply to the toilet by shutting off the valve behind the toilet. Next, flush the toilet to empty the tank of water. VqD0Bog.