OVERFLOW IS BOILING

Could be an thermostat?

Well, I would say that the radiator would be next on your list, but usually the overflow is attached to the radiator, so that should be impossible to boil before radiator. How does the temperature gauge look? Even if any parts are hot to the touch that doesn't necessarily mean they are overheated. It may be that the system is still working out bubbles, hence the overflow boiling over.

is the cooling fan coming on when it is hot?

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it could very well be a bad gauge. when it shows the engine to be overheated or at the least very hot, check the actual temp at the water outlet where the upper radiator hose attaches to the engine. use a non contact thermometer to check the temp so as not to get burned in the process. if the thermometer reads way different than the gauge, the gauge is bad.

did u perge the air out

disconnect the heat hoses going into fire wall , put hose into one with pressure and flush as it sounds like it could be bloked in the heater core,the other thing that could be the problem be the hot ,cold switch as it restricts the flow to makes the heater hoter or colder , it might need tlc or replacing as it is manaul not elec

2 possible things. 1st(cheapest) you have air in cooling system. Need to burp it. 2nd(expensive) you may have blown head gasket. I tend to think air is in cooling system and your level is low.

I HAVE A 2001 CHRYSLER CONCORD AND THE OVERFLOW IS BOILING BUT THE TEMP GAUGE IS NOT SHOWING RUNNING HOT. DO YOU THINK THAT THE TERMOSTAT IS STUCK

Check the over flow tank located in front of the passenger side glove box for water or fluid. When driving the car, listen by the glove box to see if you car hear a boiling sound. If you can hear water boiling or moving, check your heater core to make sure it is not plugged or bad. When the car starts to over heat, does the gauge register that it is getting hot? If it doesn't then check the thermostat to make sure it is not stuck open or closed. If its over heating and the gauge is not showing that the car is running hot before boiling over, then the thermostat is defective or not working. Try replacing it again.

The thermostat needs to be replaced