2001 corolla 274K miles Automatic
Car temperature rose almost to overheating and back down several times. No heat. Replaced heater core, thermostat and radiator. Heat work short period of time. Flushed coolant system and heat great for a few days then ice cold again. Car doesn't rise to overheating as much as before but inside heat is spotty. Guage sometimes rises when on slight upgrade or idling for several minutes. When in park and foot in gas, temperature guage falls but no heat. Any suggestions?
A Corolla's heater core is about the highest part of the cooling/heating system, so if there is air in your cooling system, that's where it would be. Try doing one of these processes:
https://www.google.com/search?q=youtube+purging+air+out+of+car+cooling+system
Glen_stet has the answer. A proper burping of the system will probably eliminate the air trapped in the heater core causing the thermal break. Air is not a good conductor of heat, which is why insulation is made up of mostly air.
How often do you have to refill the coolant? What is the coolant level at right now?
It was within normal levels before and after these repairs
Thanks for the help. Will update