OEM 2003 Toyota Tacoma Thermostat

2003 Toyota Tacoma Parts Questions & Experts Answers

• Q: How to service and repair a thermostat on 2003 Toyota Tacoma?

  A: Service and repair requires starting with draining the engine coolant followed by disconnecting the lower radiator hose. Open the thermostat by unfastening the two connection nuts before pulling out the water inlet with the thermostat and gasket from the water pump and cleaning off the gasket from the thermostat. The thermostat must undergo water immersion while incremental temperature increases to validate its valve opening temperature range between 80 - 84 degrees Celsius (176 - 183 degrees Fahrenheit); replacement of the thermostat is necessary if the inspection results fall short of this specification. You should check the valve opening lift measurement because it needs to reach 8 mm (0.31 inch) when the temperature reaches 95 degrees Celsius (203 degrees Fahrenheit); if the measurement does not meet this standard you must replace the thermostat. A new thermostat must be installed when the valve remains open below 40 degrees Celsius (104 degrees Fahrenheit). Install a new gasket on the thermostat then match the jiggle valve with the water inlet housing protrusion before placing the thermostat inside. Place the water inlet with its 2 nuts while facing up the top mark and torque it to 20 Nm (200 kgf-cm, 15 ft. lbs.). The installation of the lower radiator hose follows coolant addition and engine startup to detect any fluid leakage.