Hey everyone! I have an Overheating Issue on 2009 automatic Toyota Corolla with 140000 miles. Replaced thermostat, radiator cap, and water pump with proper burping air procedure. After every drive I check and the coolant reservoir is way past full almost overflowing, even though I didn’t put that much in there. I used a combustion leak tester and no exhaust gases in cooling system. As well as a cooling system pressure tester and no leaks, holds pressure. Just extremely confused since the only thing left I can think of is the radiator but don’t want to replace it without insight. Thank you.
You are supposed to fill the reservoir to the Full (Max) line when the engine is hot. You should check your temperature sending unit for corrosion and proper function.
You might want to use some compressed air or a garden hose to clean to radiator fins of 13 years of crud. Is your cooling fan assembly working properly?
Did you use an oem thermostat? I used an aftermarket one years ago that allowed my Toyota to overheat, so have only used oem since.
Yes OEM thermostat and Rad Cap from Toyota Dealership.