The serpentine belt on a Ford Focus is designed to drive the vehicle's accessories, such as the alternator and power-steering pump. This belt is powered by the engine and driven by the crankshaft pulley. It is made from special rubber that makes it resistant to shrinking in cold temperatures, preventing belt squeaking and squealing. The belt is held in place by a spring-loaded tensioner that applies pressure to the belt to ensure that it is continually taught. This tensioner must be compressed in order to remove the belt.
Shift the Focus's transmission into park for an automatic or first gear for a manual, and turn off the engine. Set the parking brake and open the bonnet. Disconnect the negative battery terminal, using the battery-terminal wrench.
Locate the spring-loaded belt tensioner. It is just above the crankshaft pulley on the left side of the engine block. Insert the square end of the serpentine-belt removal tool into the square receptacle on the belt tensioner. Compress the tensioner by rotating the removal tool clockwise.
Slip the belt off of the alternator pulley and slowly release the belt tensioner, allowing it to return to its original position. Remove the serpentine-belt removal tool from the belt tensioner.
Remove the belt from the other pulleys and pull it up and out of the engine.
A serpentine-belt removal tool is a long, thin tool made from steel that is designed to make it easier to compress the belt tensioner. Serpentine-belt removal tools are available from auto parts stores and automotive tool manufacturers.