Would The Thermostat Cause The Water In My Resevoir To Boil And Overflow

Posted in Cooling Perfomance
  • Just replaced the thermostat howser and radiator cap but not the thermostat. car runs fine for a few hours and then the water in my resevoir starts to boil and overflow and then car overheats. mechanic says he thinks it is the head gasket.

    There are 6 Answers for "Would The Thermostat Cause The Water In My Resevoir To Boil And Overflow"

    1. andy42s says:

      it could be the head gasket, but replace the thermostat first. WAY cheaper and worth a try.

    2. RIA says:

      sounds like the head gasket, my rover did the same thing,my mechanic mate fixed it for me and it ran better than ever.

    3. Scanner says:

      Thermostats rarely go bad. Only if they get stuck. Could possibly be clogging in the radiator. Is it an old car? A radiator clogged with calcium will do that. If your head gasket is defective you will see a level of gray color at the bottom of your oil stick. Wait until the car settles down to check. You can check your thermostat by boiling it in hot water and you should see it open up. This is not always a perfect test as it should open up before the water boils but it will show you if it is working or not. They rarely go bad but it does happen.

    4. bobweb says:

      Your mechanic is probably right and you can be certain by asking him to sniff the gases coming out of the radiator fill when the engine is hot and idling. He needs a gas emissions analyzer or a Snap On tester that is designed to sniff the gases from the radiator fill neck.

    5. Ray B says:

      just take the thermostat out and run it to see if its doing it you could then put thermostat in boiling water to see if it opens

    6. sidecar0 says:

      Sounds like the Head Gasket but, do you smell Exhaust in the radiator with the Engine Running? Bad Water Pump (Bad Impeller) or Clogged Radiator could also cause it.

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