Replace thermostat

Disconnect the negative battery cable and remove the engine cover.
Remove the air cleaner and intake duct.
If applicable, remove the coolant recovery reservoir.
Drain the radiator until the coolant is below the thermostat level (below the level of the intake manifold).
Remove the upper radiator hose from the outlet elbow.
Remove the water outlet elbow assembly from the engine. Remove the thermostat from the engine.

To install:

Clean the gasket surfaces on the water outlet elbow and the intake manifold. Use a new gasket when installing the elbow to the manifold.
Install the new thermostat making sure the spring side is inserted into the engine. Tighten the thermostat housing bolts as follows:

18 ft. Lbs. (25 Nm)

Connect the upper radiator hose to the outlet elbow.
If applicable, install the coolant recovery reservoir.
Install the air cleaner and intake duct.
Connect the negative battery cable and install the engine cover.
Refill the cooling system. Start the engine and check for leaks.