Engine overheating - Car thermostat problems

You are here probably because you have engine overheating problem. In this interesting and informative tutorial you will learn how to identify engine overheating causes and how to solve common engine overheating problems. The first symptom of engine overheating is, of course, the temperature gage on the dash going up over the limit. The moment this happens (most cars have sound alarming too) find a safe spot and stop the car. Find help immediately or, if you can, do the repair yourself. We advise the first if your on the road. It's a slim chance that you'll be able to make this kind of repair on the open road. In any case don't continue driving the car as you'll cause damage to the engine!
There are two major reasons for overheating due to coolant system failure: thermostat failure and radiator fan failure.Of course there might be a coolant leakage.

Diagnosis of the Engine Overheating

First of all you have to make the proper diagnosis:

  1. Start the car and let it run until it reaches it's normal temperature.
  2.  While the car is running, touch the hoses that go from the engine block to the radiator and from the radiator to the engine.  Watch your hands while doing this!!!!!
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    Car thermostat scheme
  3. If one hose is more colder than the other, while the temperature gauge is showing overheating, that's a no-circulation sign inside the system. That means that the thermostat has malfunctioned thus not enabling proper circulation of the coolant.

If you have, at this point, decided to make the repair by yourself here's the tools that you''ll need :

  1. a multi purpose screwdriver
  2. set of wrenches that match the job ( for the nuts and screws)
  3. a new gasket (or sealant)
  4. a new thermostat
  5. additional coolant fluid
  6. container for catching the coolant that comes out. (Make sure you have all of these prepared before starting.)
engine overheating car thermostat
Location of the thermostat on the engine

How to Repair Car Thermostat

  1. Locate the housing of the thermostat (you'll recognize it by the hoses coming in and out of it).
  2. Put the container under the casing so you can catch the coolant that comes out
  3. Take the casing lid off with the proper wrench or screwdriver and take out the faulty thermostat. Replace it with a new one. Be careful as coolant fluid will start flowing out.
  4. Make sure you change the gasket on the lid and put it properly to avoid leakage. If you don't have a gasket use a sealant preparation.
  5. Tighten the casing lid gently and evenly on all sides.
  6. Turn on the car, let the engine run. Touch the hoses again (on the radiator) and if they are equally hot you've done a good job. This means that the coolant circulation is back to normal. Wait until the temperature has risen to normal and wait for the radiator fan to start.
  7. Add additional coolant fluid if needed
  8. Check for possible leaks on the thermostat casing. In case of leakage, try to tighten the lid a bit more. If that doesn't work try re-sealing the lid again.