Stingray, the original Harrison radiators are very heavy, mostly copper construction and yes very hard to resoldier without an oven due to design. And yes they can be "rodded" out.On my 45 big truck,it could idle all day and never heat up but a long drive would have it boiling over , classic sign of a bad radiator.I pulled the radiator, hole sawed a few one inch holes in the top tank, took a choke cable inner wire and cleared the tubes. Most of the blockage is near the top of the tubes. I then CAREFULLY filled the radiator with a solution of half water and half muriatic acid.Let it sit for 10 minutes and then flushed out the radiator with plently of water.The acid thourghly cleaned the radiator.I then soldiered thin brass sheeting over the holes in the top tank.The radiator has performed no problem for the last 3 years.
