What I would do is drain all the antifreeze in a container. When system is empty and safe then with the engine cold disconnect the bottom hose of the radiator. If its warm enough where you are above freezing I would flush out the radiator by putting a garden hose where the cap goes and let if run. You might want to do the same to the engine. With stopleak it gets on everything inside. After you have flushed the system really good, then replace the thermastat. You can use a 160 themastat. Reattach all the hoses then before starting the engine fill with water. Start the Blazer run a little while then check the temp. If the blazer temp is ok, drive the car for a day to make sure that is the problem. If everthing is ok after a day then drain the system again and fill with coolant. Make sure to check the leak that someone said was in the radiator is not leaking. Stopleak could make a themastat stick and cause overheating. Another thing is you might want to back flush the heater core. I think prestone has a kit that one can put in line so someone could flush the sytem easier.
Thing to remember that antifreeze is dangerious to animals and people if injested. So be careful not to spill it.
Tuesday, May 26th, 2009 AT 2:22 PM