I have 2 small pinholes on top of radiator. Can I solder those using the same flux and solder I use for sweating on copper fittings? Will a propane torch be too hot? Can you use a soldering iron? What about one of those micro torches? I know there is a lot of solder in a radiator and I am affraid to melt any inadvertantly. I also assume you would have to empty out coolant. Any advice greatly appreciated. How about using epoxy putty?