So my 3.8 started overheating in the middle of last week, so i parked it and thought it was a simple fix so i just topped off the coolant and changed the thermostat. Well my engine is still over heating and now I've ran it with and with out the new thermostat, The hose/water line that goes from the radiator to the engine block swells up like a balloon (because of this i doubt its the water pump) and gets extremely hot, also i noticed that the radiator remains cold to barely warm. So does anyone know what to do or have any experience with this issue?

 

Flush your radiator out.