for those trying this repair, note that copper pipe comes in several thicknesses. M is the most common copper thickness for plumbing, it is very thin, K is much thicker available as 1-1/8" refrigeration tubing. L is WAAAAAY thicker, but difficult to find. you may need to track down a HVAC truck to get a chunk of K, because, plumbing supply houses sell it in 21'lengths usually... just a bit more than ya need to fix a radiator.