Can't solve the overheating issue. Replaced thermostat, water pump and had radiator checked.. no blockage. The heater is not working. Car overheats within 10 minutes. The upper hose is hot but the lower hose (where the thermostat is) is cold. I have bench tested 2 thermostats and they both open at about 185 degrees. Someone mentioned that I need to "Burp" the engine as I may have an air pocket preventing water flow. Never heard of such a thing. Any help and directions?