Car overheats. i unplugged temp sensor and fans suddenly came on and coolant started to flow. Hoses werent backed up any longer. So i replaced fan relays and car is still running hot

Start the engine and warm up. Feel the upper and lower radiator hoses while it is warming up. You should feel heat suddenly in one of the hoses-usually the top hose. If it does not get hot but the engine get hoter than 1/2 way up the guage then you have a bad thermostat.

coolent level ok.

i would check and make sure the cooling fan is operating,if not it will overheat sitting still.a thermostat will cause overheating whether or not it sits still or driving(more so when driving).the same if it has a bad water pump although it may circulate just enough coolant when driving to not overheat with air flow also adding a cooling effect.if you don`t have a leak then i would say the water pump is okay as they usually will leak before causing a overheat problem.make sure the cooling fan is working and the rad does not have anything stopping the air flow over the rad and is not stopping coolant flow in the rad.

thermostat bad,fan not running,sensor bad. I would start the car and let it run while watching to see if the fan comes on and feel to see if the hoses are flowing water though the radiator. Hope this helps Tim

You will need to see if the fan operates when overheating, there are diffrent sensors for the cooling and ac cooling, the good thing is that the fan works, this would tell me it may be a bad coolant temp sensor or thermostat, you will need to let it run and as the gauge passes the middle point feel to see if both upper and lower rad hoses are hot, if only one is hot then you may have a bad thermostat, is they are both hot and fan doesnt turn on and car overheats then you should replace the coolant temp sensor, stat with these tests and see the result, hope this helps.

okay, if it turns on with coolant temp sensor unplugged, then this tells me that the fan is good and also relay is good, you replace thermostant, and the sensor, you covered all those bases,now we go into coolant flowing,this tells me the coolant is not flowing inside the motor,two thing can cause this, one being the waterpump, the impeller may have broken or rusted, and the next would be exhaust entering the cooling system restricting the flow and making it overheat,this is gasket from a headgasket problem. the next thing i would do is to have a block test done to see if exhaust is entering the cooling system, good luck.

NO, the sensor is good.

If you unplug the coolant temp sensor the computer will turn on the fans because it doesn't know how warm the engine is. The computer is working like it is suppose to. I think you might have a bad coolant temp sender. If it was a problem with the fans or the relays, they wouldn't come on when you unplug the sensor, because the problem would still be there.

the car is heated at low speed because less air flows at high speed and does not heat because the air flows more, check if the fan is turning on and check if you have good revolution,, check fuses, check the thermostat temperature, clean radiator use antifreeze coolant and finally check the pulley on the water pump with its setting correct ajustment. and finally if you work on the motor over time, verify that the ignition times are in place,

The coolant temp sensor tells the computer tempurature of engine at all times.It tells the coolant fans to come on,and also very important,when to cut off.If the fans don`t go off by them selfs,then temp is not going down.Now this is if the ac is off,cooling fans come on any time ac is turned on,so check for fans coming on and off with ac off.A bad coolant sensor would cause the fans not ot come on,but not to cut off nessasaralyCoolant systems must be bled of air trapped in systemfor the engine to be cooled .If air is in the system,the coolant won`t flow correctly.