OEM Toyota Yaris Thermostat

Toyota Yaris Thermostat Parts Questions & Experts Answers

• Thermostat
  90916-03093
  Q: How to service and repair a thermostat on Toyota Yaris?

  A: The engine coolant needs draining before starting any servicing or repairing work on the thermostat. The next step requires removal of the water inlet by unfastening its 2 nuts to separate it from the cylinder block while removing the radiator hose. You should start by removing the thermostat from the cylinder block and then eliminating the gasket from the surface. Before replacement verify the thermostat functions by heating water then evaluate its valve opening temperature between 80 to 84 degrees Celsius (176 to 183 degrees Fahrenheit). Check that the 8.5 mm (0.335 in.) minimum valve lift measurement is present at 95 degrees Celsius (203 degrees Fahrenheit) temperature while validating that the valve closes completely under 77 degrees Celsius (171 degrees Fahrenheit) conditions. Thermostat replacement is needed if either of these criteria fails. The installation process requires a new gasket on top of the thermostat followed by installation orientation with the jiggle valve upward at an angle tolerance of 10 degrees. The radiator hose water inlet needs to be installed with its 2 nuts tightened to 9.0 N m (92 kgf cm and 80 in. lbf). Finish the process by pouring engine coolant into the system followed by a leak inspection.