overheating when idle

[thatdamngoodcire777]

I can't find much info about my problem on this forum so I'm posting this. The needle for the coolant on the dash keeps fluctuating between hot and cold. It goes all the way past hot when it idles too long and stays in the middle and higher when driving any speed. I've seen no smoke and no leaks anywhere. The coolant level is fine and was changed a few months ago. I'll start with the thermostat and go from there. BUT, how do I replace the thermostat in a 00 solara? What else should I look for? Oh, and the head gasket had been changed a couple years ago too. I can't afford to lose this car...

[TheGreenDutch]

What happends at idle when you run the heater on high? Does it level it off? Sounds like a thermostat hopefully its that but the head gasket could be going again. Check your fluid levels and check their colors. If you have oil in the radiator fluid then you have problems man. Good luck.

[solara90]

are your cooling fans kicking in?

[Mole]

faulty water pump ?

[02slera]

id say the fans may not be coming on.
when you drive, air naturally goes through your radiator and provides cooling.
when you idle, air has to be pulled through the radiator via the electric fans which should come on when a certain temp is reached.
the fans should also come on when running your ac.
the thermostat is a good place to start because of the cheap cost, but before you spend any money, i would make sure the fans are operational.
i have never changed the thermostat on the solara but usually it is located where the upper radiator hose connects to the motor.
also, if the fans are not coming on, check all fuses and relays and related wiring.

as mentioned above the water pump could be faulty, but from my experience on other cars, they usually have a "weep hole" and will leak when they are going bad, though that is not guaranteed. i would make sure the fans work and change the thermostat first.

[dug320]

It sounds like classic thermostat issues. Water pumps rarely stop pumping without significant indicators like noise and leakage.

But to rule out other issues I would short out the rad sensor to test the fans and the relays. You could pull the rad sensor switch and test it in hot water.

What you should worry about is the impact of running it hot on the head(s) and the seal of the head gasket. Oil in the rad fluid and or white smoke in the exhaust are key indicators.

[thatdamngoodcire777]

Thanks for the replies. The car still doesn't have any smoking from the engine or the exhaust, any warning lights, no codes, no stalling and no leakage from the water pump. It does have new leakage froim the lower radiator hose which is causing severe coolant loss, the engine is running slightly lowder but the fans still work fine. The coolant level regulate when the car is moving but not when idle. Also, the coolant that is leaking doesn't look discolored like it might contain oil. Thinking its might not be the water pump or the head gasket from what I can see. I'll replace the lower hose tomarrow and change the thermostat. I'll test everything I need to if this doesn't solve the problem.

[TheGreenDutch]

yeah man a hose will do it. Change it before it kablammos all over....lol

[thatdamngoodcire777]

Ok, replaced the leaky lowes hose and changed thermostat. Now shes running like normal so hopefully thats that.