Replacing the thermostat in the 2001 Ford Focus will only take a few minutes, as the thermostat is located at the top of the engine. The purpose of the thermostat is to regulate the coolant system to prevent the engine from overheating. A faulty thermostat will stick and not allow the coolant to enter the engine. Replacing the thermostat on the Focus is straightforward, as it is located at the engine end of the upper radiator hose.
Lift the bonnet and prop it open. Follow the upper radiator hose to the thermostat housing. The thermostat housing is attached with three bolts.
Unscrew the three bolts with a socket wrench. Pull the top of the housing off.
Lift the thermostat out of the housing. The thermostat rests at the bottom of the housing.
Remove any gasket material off the mating surfaces of the housing. Scrape off the remnants of the old gasket with a razor scraper.
Insert the spring end of the thermostat in the housing.
Lay the new gasket around the mating surface of the stationary part of the housing. Place the cover on top and secure it with the three bolts.
Tighten the three bolts with a socket wrench. This will create a seal to prevent leaking in the future.
Twist the radiator cap off. Pour in coolant to the radiator until the level is full.
Start the Focus and allow it to idle. Once the car is warmed up, the coolant level will go down. Pour in additional coolant until the level is full. Tighten the radiator cap.
Turn the engine off and close the bonnet.
The thermostat and gasket can be purchased as a kit at any local auto parts store.
Use caution when working around the coolant system. Allow the vehicle to cool down before changing the thermostat.