Karl Middleton

Hopefully someone here can help me out. I have a 2012 C350 sedan with 70k miles. Had an overheating issue and took it to the dealership and it failed the test for the thermostat. They wanted way to much to replace it so I figured I would do it myself since I've changed them before on other domestic vehicles. I have replaced the thermostat and now trying to refill the coolant. After filling the overflow reservoir I closed it and started the car. Turn the heater on high and let it run up to operating temp. But the heater never blows hot air.. this was not the case with the bad thermostat. And when I shut it off and let it cool down there is not any room in the reservoir to add coolant. The car still wants to over heat, which I'm guessing is due to the lack of coolant Help?