How to put a thermustat

Remove the air cleaner intake duct.
Partially drain the cooling system.
Remove the radiator inlet hose from the thermostat housing.
Remove the thermostat housing bolts.
Remove the thermostat.
Clean and inspect the thermostat housing gasket mating surfaces.

To install:

Install the thermostat.
Install the thermostat housing.
Install the thermostat housing bolts and tighten to 18 ft. Lbs. (25 Nm).
Install the radiator inlet hose to the thermostat housing.
Install the air cleaner intake duct.
Fill the cooling system.
Start the engine and check for leaks.