The 2000 Ford Explorer uses a mechanical, spring-operated thermostat to regulate engine temperature. It is essentially the same thermostat Ford has used on all of their liquid-cooled engines. As the temperature of the antifreeze heats up, the spring inside of the thermostat compresses. This allows the thermostat to force fluid through the cooling system of the Explorer. Ultimately, this process prevents the engine block from overheating and avoids thousands of dollars in damages to the engine.
Remove the thermostat housing from the engine block of the Explorer. The easiest way to locate the thermostat housing is to follow the upper radiator hose to the location where the hose connects to the engine. The hose connects to the housing. Hose removal is not required for removal of the thermostat housing.
Remove the 7/16 bolts that secure the housing to the engine block of the Explorer with a socket and ratchet. There are two bolts in total. Lift up on the thermostat housing, and push it and the hose off to the side so you can access the thermostat.
Remove the fabric thermostat gasket from the engine block and throw it away. Wipe the surface of the engine block clean with a rag.
Pull the old thermostat out of the engine block and throw it away. Place the new thermostat into the engine block. The end of the thermostat with the large spring sits inside the block, on a machined lip that sits just inside. The end with the jiggle valve sits inside of the thermostat housing.
Place a new fabric gasket onto the mating surface of the engine block and place the thermostat housing on top of it. Bolt the housing ans gasket into place with the original mounting bolts.
