Place a large drain pan beneath the radiator drain plug on the driver's side of the Villager. Open the hood and remove the radiator cap.
Turn the radiator drain plug by hand until the coolant starts to flow. Watch for the coolant level to drain below the upper radiator hose. Tighten the drain plug and remove the drain pan.
Follow the upper radiator hose from the radiator to the opposite end to locate the thermostat housing. Remove the mounting bolts securing the thermostat housing to the engine with a wrench. Remove the thermostat from the housing and dispose of it.
Clean any gasket remnants from the housing with a scraper or putty knife. Wipe the surface clean with a soft cloth. Insert the new thermostat into the housing, place a new gasket on the mounting surface and secure the housing in place with the bolts. Tighten the bolts with a wrench.
Fill the radiator with a 50/50 mixture of coolant and distilled water until it reaches the bottom of the filler neck. Replace the radiator cap and close the hood.