My car is overheating while idling at light. I have been driving it without a thermostat for about 6 months. I have had the water pump replaced and the reservoir. I have also replaced the reservoir cap. I have driven it for 3 days with engine/ radiator cleaner in it to make sure there is no clog but the car is still running hot. Any ideas where to go next?

1 Answer 1


I'd check to make sure that the fan in front of the radiator is operational and not missing any fins or the shroud. And it would be best to install a thermostat, since your cooling system probably isn't pressurizing without one, which means it can absorb less heat.

Do not check with your hand!

  • OK so the fans are both working. Took it about 20 miles up the road and while driving 55 miles per hour the temps temperature gauge stays in the middle. As soon as I stop at a light it climbs to hot. I pulled over and the coolant is coming out from reservoir cap and from water pump bleeder. If I reinstall a thermostat will that help it to keep the fluids in and prevent it from overheating?
    – Rebecca
    Jun 21, 2016 at 19:49
  • Yes, without the thermostat the system can't pressurize, so it boils over. The good news is it's about a $6 part. The bad news is you need to wait until it's completely cooled to put it in. Stay safe! Jun 21, 2016 at 19:57

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