I have an 03 Chevy Trailblazer that started overheating so i replaced the radiator and thermostat thinking that should rectify the problem. Well it wasnt till then i noticed the leak under the passenger side wheel well. now the only thing that can leak in that area is the heater core, Am I correct? it still overheating but can go about 20 miles before it does. i guess my question is can a heater core make your vehicle over heat? I got to get this fixed asap and i dont know what to do...

 

Welcome from Florida. When the heater core leaks it will leak inside the car on the passenger side. Look for a leak under the hood such as a hose even a freeze plug.

 

low coolant can definitely make your car overheat. Be careful or you could destroy your engine.

 

Plug in a capable OBD II code reader/live data scanner and see what temperature is being reported to the PCM by the Engine Coolant Temperature (ECT) sensor. You could have a defective ECT sensor.