[SSsssteamer]

I have had good success in soldering up radiators using the old heavy duty copper soldering irons like the radiator shops use. The heavy soldering iron gives the penetrating heat exactly where one needs it. More importantly than the soldering iron is preparation. Cleaning out the old solder and then tinning the surfaces so that they can take the new solder. For a huge success, the surfaces have to be hospital clean and tinned before you start the soldering reassembly.