I noticed the radiator water in my 99 Tahoe was looking dirty. So I drain it take out the thermostat and put therm cover back on. Hook my hose to the hot water and began flushing. Until the water ran clear. Put everything back together and filled it up. It was getting dark so I quit working on it. Next morning theres a puddle sure enough the radiator got a hole in it. I presume its from flushing all the rust out.