Thermostat
1 Answer
If it is overheating, losing coolant and has no apparent leaks it may have a bad head gasket. This will introduce exhaust gases into the cooling system displacing fluid in the highest part of the cooling system which is usually the heater core. The heater core is designed to transfer heat from a liquid and not a gas. Also the heater core could be plugged up with deposits. How quickly does it overheat? https://www.justautorepair.com/chevrolet/impala/no-heat-temp-gauge