Genuine Toyota Avalon Thermostat

Toyota Avalon Thermostat Parts Questions & Answers

• Thermostat
  90916-03084
  Q: How to diagnose and replace a faulty thermostat in a cooling system on 1997 through 2001 Toyota Avalon and 1997 through 2001 Toyota Solara?

  A: Before assuming the thermostat is the cause of a cooling system issue, perform a general check by examining the coolant level, drive belt tension, and temperature gauge or light operation. If the engine takes a long time to warm up or the thermostat is stuck open, replace it with a new one. To further test the thermostat, remove it from the vehicle and suspend it in cold water using a string or wire. Heat the water while observing the thermostat and note the temperature at which it begins to open and when it is fully open. Compare these temperatures to the specifications. If the thermostat fails to open or close as specified, or if it sticks in any position, it should be replaced. To remove the thermostat, disconnect the negative battery cable, drain the coolant, and detach the radiator hose or water inlet pipe. Remove the water inlet pipe on four-cylinder models or unbolt it on V6 models. Remove the fasteners and electrical connectors from the thermostat housing, detach the housing from the engine, and remove the thermostat while noting its installation direction. Clean the sealing surfaces thoroughly. During installation, ensure a new gasket is evenly fitted onto the thermostat, position the thermostat and housing with the jiggle pin at the highest point, tighten the housing fasteners to the specified torque, and reinstall the remaining components in reverse order. Refill the cooling system and, for V6 models, bleed any air from the system. Run the engine, check for leaks, and verify proper operation.
• Thermostat
  90916-03129
  Q: How to replace a thermostat in a cooling system on 2002 through 2008 Toyota Solara and 2002 through 2006 Toyota Avalon?

  A: First of all, a detailed thermostat test can be done when removed. If it stays open at room temperature, it's faulty. To test, suspend it in cold water and heat it, noting the temperatures at which it opens and closes. If it doesn't function as specified, replace it. To replace, disconnect the battery's negative cable, drain the radiator coolant, and disconnect the radiator hose from the thermostat housing. Replace the thermostat and gasket, and reinstall everything. Refill the cooling system, bleed air from V6 models, and check for leaks and proper operation.