Automobile Repair/Nissan/Maxima (4th Generation)/Replacing the engine thermostat

The Engine Thermostat controls how much coolant flows throw the engine. It should be replaced if the engine is consistently cold (if the thermostat is stuck open) or if the car is getting too hot or over heating (if the thermostat is stuck closed). Its a good idea to replace the thermostat at the same time your changing the coolant, because the coolant must be drained to do this.

Tools/Parts neededEdit

  • Oil pan
  • A new engine thermostat
  • A new engine thermostat seal (optional)
  • Socket wrench set
  • A Phillips-head screw driver
  • A set of large pipe pliers (optional)


  1. To start remove the engine coolant by removing the plastic Phillips-head screw from under the radiator, letting the coolant fall into the oil pan
  2. Now we have to make some room to work, remove the alarm horn and move it aside.
  3. Lower the belt adjustment bolt that is sticking put vertically next to the engine thermostat until it is out of the way.
  4. Loosen the bracket with the Phillips-head screw driver and pull it off. If you are having trouble getting it off use a set of large pipe pliers to twist if off (being careful not to damage it).
  5. Now remove the three bolts holding engine thermostat with your Socket wrench and pull it away.
  6. Push the new one in to place with the seal on it and tighten the bolts.
  7. Reattach the hose and tighten with the Phillips-head screw driver.
  8. Rise the pulley adjustment bolt all the way and reattach the alarm horn
  9. Put the coolant back in the engine and your done.