Car is overheating. Flushed three times--no improvemrnt. Can run pretty well with heater on and windows open. Doesn't heat up at idle speed. Someone suggested a loose fan belt but it is hard to find.,,Any ideas?

Do the cooling fans come on ? Your vehicle should have two fans controlled by The PCM - engine computer energizing three different relay's for low and high speed .

Possible, with rad cap off, let vehicle idle until coolant fan comes on then shut vehicle off for 30 minute cool down. Top up rad, install cap and drive and recheck heater operation and any overheating.

For car running hot and overheating issues,i suggest to you go through this help links. Click this link below and go through the troubleshooting procedure to take care of the problems :----Car runs hot? http://howtobyme.blogspot.com/2011/11/car-runs-hot-in-traffic.html
-----------All types of car overheating problems and troubleshooting?

http://technoanswers.blogspot.com/2011/11/all-types-of-car-overheating-problems.html
Car freeze overnight and started overheating while driving?http://technoanswers.blogspot.com/2012/01/car-freeze-overnight-and-started.html-----------Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Car overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
--------overheating? http://schematicsdiagram.blogspot.com/2011/12/buick-century-overheating.html
----------Car engine Overheats and transmission starts slipping?http://schematicsdiagram.blogspot.com/2011/12/car-engine-overheats-and-transmission.html
----------This details will help.Thanks.

For car running hot and overheating issues, I suggest to you go through this help links. Click this link below and go through the troubleshooting procedure to take care of the problems: ----Car runs hot? http://howtobyme.blogspot.com/2011/11/car-runs-hot-in-traffic.html
-----------All types of car overheating problems and troubleshooting?

http://technoanswers.blogspot.com/2011/11/all-types-of-car-overheating-problems.html
Car freeze overnight and started overheating while driving?http://technoanswers.blogspot.com/2012/01/car-freeze-overnight-and-started.html-----------Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

---------------------------

Car overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
--------overheating? http://schematicsdiagram.blogspot.com/2011/12/buick-century-overheating.html
----------Car engine Overheats and transmission starts slipping?http://schematicsdiagram.blogspot.com/2011/12/car-engine-overheats-and-transmission.html
----------This details will help.Thanks.

Air in the system , bad water pump , cooling fans not working ! Maybe you should take to a shop ?

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.

Bad heater core.

is the fan working? if the fan isnt working it will overheat when idling, as it wont be sucking cold air through the radiator. a quick way to diagnose that your cooling system is fine is when stuck in traffic, turn your heaters onto hot, if the engine temp gauge shows that the engine is cooling down, the cooling system will be fine 9/10 times.

hope this helps.

The heater stopped working because there was no coolant in it. Your real question is where is the water going.

Have the cooling system pressure tested to be sure you have no leaks. You said you had the radiator flushed, I suspect some of the tubes are blocked, it should be dissassembled and rodded then cooked out. Not just flushed. You problem is in traffic, low speed. The car starts to over heat, it blows the water out of the overflow, the level is down, the heater stops working, then you are out of water in the engine and overheating.


BTW ground the wire that goes to the warning light sensor and be sure it lights the warning light. If htis is the case the sensor is bad. I assume when you turn the key on but before starting the light does work then, correct? That means the bulb is ok, that does not check the sensor.

Good Luck!

Sounds like Heater matrix blocked, check pipes going from engine bay into bulk head both should be getting hot if one is not then may be worth removing pipes and trying to flush it through as would be expensive to renew it as its a large job.