ah-the last thing before i'm road worthy  got the engine all back together but was gonna replace my rear heater "o-ring" before i filled it up since I had the sweet smell going on back there. pulled it all out--which was a major PITA by the way in the 7 seater. hind sight 20/20--I would have cut the lower part of the protective case to get it to lift right off--instead--I pulled the seat out.  anyway--thought I would run some air pressure through the core since it looked a little crusty. I made a system out of some of the replaced hoses and a valve stem hooked up to a bike pump. glad i did since i got it up to about 20 lbs and it was leaking out along the edge of the core to the plastic mating surface.  onto my question. is there a way to seal them at a radiator shop--or am I stuck buying a new one or a known good one? I'm onto look at vendors web sites now to see what they cost  thanks in advance  mike