OEM 2007 Toyota Highlander Thermostat

2007 Toyota Highlander Parts Questions & Experts Answers

• Q: How to service and repair the thermostat on 2007 Toyota Highlander?

  A: Service and repair sessions for the thermostat require engine coolant drain first. The first step is to remove the V belt which connects the fan and generator after which you should remove the generator assembly. Remove the water inlet from the cylinder block by disconnecting its 2 nuts before detaching the radiator hose inlet. Examine the thermostat after removal because it carries two essential markings including its valve opening temperature number and stamped valve opening specifications. The thermostat should undergo a water-bath process while heating until its valve opening temperature reaches 80 to 84 degrees Celsius (176 to 183 degrees Fahrenheit). The thermostat needs replacement when the measured valve opening temperature fails to align with the required 80 to 84 degrees Celsius (176 to 183 degrees Fahrenheit). Check the valve lift because it should measure at least 10 mm (0.39 inch) when water reaches 95 degrees Celsius (203 degrees Fahrenheit). If the lift does not meet this level the thermostat must be replaced. Replacement of the thermostat should occur whenever the valve remains open below temperatures of 77 degrees Celsius (171 degrees Fahrenheit). To install the thermostat apply a new gasket before setting it in position with its jiggle valve at the upper half and allowing the jiggle valve's position to vary by 10 degrees from the recommended direction. Install the water inlet by torquing the two nuts until they reach 9.0 Nm while also reinstalling the radiator hose inlet, generator assembly and fan and generator V belt. Engine coolant treatment should follow the leak inspection to complete the maintenance process.