[Silverbullet]

if a thermostat is the cause of over heating it means its not opening. Its not likely for a thermostat to not open. If they go bad, its usually the seal that breaks and causes ur car to not heat up durring the winter. But to test ur thermostat, u must take it out, put it in boiling water. If it starts to open, ur A OK. Most likely u have air in ur system. Open your rad cap and turn the car on and watch the water level go down lol. Fill upto full. Do not do this when ur car is hot.