Compare the temperature difference between the upper and lower radiator hose. If there is a vast difference and the air being pulled by the cooling fan is not extremely hot, you have a coolant citculation problem. It could be clogging, a bad water pump or stuck cloded thermostat. Though you have replaced the thermostat, new parts do fail too.
Try removing the thermostat and running engine to see if the overheating still occurs. This might take a longer running time to overheat.
Tuesday, October 16th, 2012 AT 6:28 PM