Replaced Thermostat - Vehicle still Overheating

[Jeff Robinson]

My vehicle began to overheat 2 days ago. I replaced the thermostat, and today I drove the vehicle for over 100 miles then it overheated again. What else could be causing it to overheat? I turn the heat on and at first the air doesn't blow out hot, eventually it does then the temp gauage goes back to normal operating temperature

 

[boominXplorer]

Small coolant leak then your getting air in the system. Since the radiator is designed with the fins going up and down as soon as your a little low on coolant it will airlock unfortunately and overheat.

 

[07EddyB]

How many miles?
Rear heat?
Did you bleed the air out of the system after replacing the thermostat?
Are you leaking coolant?