How to Replace the Thermostat in a Ford Explorer

The Ford Explorer comes with three different engines in most years: the 4.0-, 4.6- and 5.0-liter engines. The thermostat is always on the engine side of the upper radiator hose, and is encased in a housing. If the thermostat sticks closed, the water does not circulate and the engine overheats. Thermostats come in various temperature settings, varying from 160 to 192 degrees. The typical temperature to operate an engine is 185 degrees. If you buy a 185-degree thermostat, when the water reaches 185 degrees, the thermostat opens and allows the water to flow through the radiator to cool it.

Place the drain pan under the drain bolt on the radiator. Loosen the drain bolt and allow the radiator fluid to drain. If the drain pan is clean, you can reuse the antifreeze.

Loosen the hose clamps on the upper radiator hose using a socket, screwdriver or pliers, depending on the type of hose clamp on the hose. Pull the hose off the radiator and thermostat housing. If the air filter intake hose is in the way, loosen the clamps and remove the intake hose (on some engines).

Unbolt the two bolts in the thermostat housings. Pry the thermostat housing off the engine block. Pull the thermostat out of the housing. Remove the old gasket and discard. Slide the new thermostat into the housing the same way the old one came out. Install the new O-ring seal in the housing. Coat the housing with a thin layer of silicone gasket maker. Allow the gasket maker to dry.

Slide the bolts into the thermostat housing, then line the bolts up to the bolt holes on the block. Slide the housing down the bolts until it touches the block. Turn the bolts in by hand to get them started. Tighten the bolts to 89 inch-pounds of torque.

Reinstall the upper radiator hose. Tighten the radiator drain plug. Fill the cooling system. Start the engine with the radiator cap off. Allow the engine to come up to operating temperature. Look for leaks. Watch the level of the water in the radiator. Fill as needed.