I have an 04 civic EX with an overheating problem. See below for details:

Car has 185,000 miles, water pump replaced at 120,000

Temp is good at highway speeds, but as soon as I stop or slow down the car begins to over heat. Immediatly before the overheating starts the heat in the car stops working and does not come back until the car cools down.

After overheating I wait for car to cool, fill radiator and run with the cap off until hot, then I continue to top off the radiator unitl cool again.

After topping off the radiator the car will run fine for about 2 hours before the overheating happens again.

During an overheating episode I popped the hood and found that the radiator cooling fans were not working. I hit the AC button and the fans started, so I think that the fan motors are ok, but I think that my problem is that the fans do not turn on when the car gets hot.

So far I have:
1) Checked the fuses
2) Replaced temp sensor and fan switch
3) Replaced fan relay

I am contemplating direct wiring the cooling fans, and am going to replace the rad cap and maybe the thermostat.

Any suggestions....

 

This sounds like a head gasket leak since the heater stops working before overheating occurs. Gas leaked from the head gasket is displacing the coolant and causing a bubble in the engine and radiator then it can't flow and overheating occurs.

You could just test drive with the A/C on (disconnect the compressor so there is no extra heat burden) to make the fans run all the time. I doubt that it will help.

 

Thanks for the info, I am going to try running the car with the AC on this weekend. Oil and exaust both look good, would this be possible with a blown head gasket?