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How to Change the Thermostat in a Toyota Highlander

by Contributor

The Highlander has a unibody design like a car which provides better handling, a quieter cabin, increased safety, and easier access in and out for passengers. It appeals to buyers who want the SUV image and utility but prefer the feel of a car. Toyota debuted the Highlander in 2001 with an impressive list of standard options. The following steps guide you through the installation of the thermostat on models with the 3.3L V6 engine.

Step 1

Drain the cooling system. Drain the coolant into a sealable container. Disconnect the battery ground.

Step 2

Take the radiator outlet hose from the thermostat. Loosen the bolt and then move it to remove the water inlet pipe. Remove the bolts that secure the water inlet and remove it.

Step 3

Lift out the thermostat. Pull the gasket and discard it. Clean the gasket mating surfaces thoroughly to remove any gasket debris, carbon deposits and dirt.

Step 4

Set a new gasket on the thermostat. Set the thermostat in place, aligning the jiggle valve with the upper stud bolt. Place the thermostat into the water inlet housing.

Step 5

Connect the water inlet. Torque the bolts to 71 inch pounds.

Step 6

Lubricate a new O-ring with soapy water and then install it on the water inlet pipe. Set the inlet pipe bolt in place to secure the pipe to the cylinder head. Torque the bolt to 15 foot pounds. Connect the radiator outlet hose.

Fill the cooling system to proper levels with the appropriate coolant. Start the engine, check for leaks and add coolant as needed.


  • Dogs and cats are attracted to and will drink coolant left in open containers or puddled on the floor. Ingestion is often fatal.

Items you will need

  • Mechanic's toolset, including a full socket set, wrenches and screwdrivers
  • Replacement thermostat, new or rebuilt
  • New gasket for thermostat

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