Both of these symptoms can be caused by low coolant level but with the parts you replaced already, at some point the system should have been filled.
The next thing is to feel the hoses when the overheating occurs. If the upper radiator hose is cool, a leaking head gasket might be a suspect. Combustion gases can pool under the thermostat and prevent it from opening. Thermostats have to be hit with hot liquid to open. Hot air won't do it. If the hose is hot, feel the two heater hoses. They should be too hot to hold onto for very long. If they are cool, the heater core is likely plugged. Remove the hoses from the engine, then run water through them from a garden hose. I prefer to not remove them at the heater core because besides limited access, on some cars you run the risk of breaking the solder bond between the pipe and the heater core, then you have an expensive leak.
Do you get hot air inside at highway speed?
Tuesday, April 21st, 2015 AT 3:35 PM