How do you know wene your cars thermostat is not working proper?

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  • 7 years ago
    Best Answer

    If your thermostat gets stuck closed, your car will overheat, generally in 10-15 minutes after you start driving. If your thermostat gets stuck open, your car will generally run cold, never getting up to temp. However, a thermostat that is stuck open, on certain cars, will let water flow through the radiator to quickly, and the radiator will not properly cool the water, causing the car to overheat as well, but this is generally when running a car with a small radiator at high RPMs, and it would take a while for it to overheat.

    HOWEVER, just because your car is overheating DOES NOT mean your thermostat is not functioning properly. if you have a car with electric cooling fans (most front wheel drive vehicles), and the fans are not turning on due to bad sensors, a bad fuse or relay, a loose wire, or number of other things, this can cause your car to overheat as well. On rear wheel drive cars with a clutch fan, the clutches can wear out and cause the fan not to engage properly as well, causing cooling problems. Radiators can become plugged, and not allow proper flow of coolant, and sometimes a blockage on your radiator, like mud, road debris (plastic bags or cardboard) can black air flow through the radiator and cause the car to overheat as well.

    You can check your electric fans easily, when the car rises above normal operating temp, open your hood and see if the fans are working. Check the radiator to make sure it is clean and free of debris. IF both of these are are not the problem, then remove your thermostat. If it look corroded or the spring is unable to be depressed, then replace it. If that does not fix your problem, then you need to look into having your radiator flushed.

    Best of luck

  • 7 years ago

    When a thermostat is stuck open the dash temperature never reaches 205 degrees and the heater will not kick out hot air. If you has listed the year make and model of your car we could have let you know what temperature thermostat should be in the cooling system.

    Source(s): Alignment, suspension and brake shop.
  • roger
    Lv 7
    7 years ago

    It can fail when the thermostat is shut and the car will overheat within a few minutes of starting. Or it may take 15 minutes or more before your heater starts to work properly in the morning when its cold. because it is stuck open. you can tell if its stuck shut because the upper hose going to the thermostat will be empty instead of full after the car has been running for several minutes.

  • 7 years ago

    If your car overheats a lot with steam coming out from under the hood then that's a good sign that the thermostat is going bad.

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  • Anonymous
    7 years ago

    when you start from cold, it should take a few minutes while driving to get up to operating temperature, if it take an abnormally long time to reach operating temp, it means your thermostat is stuck in the open position. Of course if the cars continually overheats then obviously it is stuck in the closed position...

  • 7 years ago

    I once had a thermostat that was stuck open resulting in my car taking a VERY long time to warm up and when it was cold out it barely showed anything on the temp gauge.

  • 7 years ago

    A thermostat normally fails in the closed position, so your engine overheats.

  • 7 years ago

    It over heats Or it dont get hot enought.

    Source(s): drpeppers
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