we have a Chevy 97 k2500 that prior to winter had a rear heater line that was leaking just under the passanger front seat at a Y, over the winter it sat with water in the lines and froze, thus cracking our radiator. so we have replaced the radiator, thermostat, water pump and a friend "capped off" or dead ended the leaky line just before that Y. These were copper pipes. The sububan will start and run fine but the temp pegs out (in the red over 250). Any suggestions on what problem is and how we can fix it ourselves.
thanks!