The serpentine belt on the front of a Ford Ranger 3.0L V6 engine is responsible for driving the power steering pump, A/C compressor, water pump and alternator off of the power from the crankshaft. If the belt goes out, then you'll be without all of those accessories, and you'll run into a myriad of problems. Fortunately, fixing the problem, before it happens, is easy, and can be done with one tool in about 15 minutes.
Pop the hood to the truck. There is a sticker on either the core support or the hood of the truck, with a belt routing diagram. Locate that sticker, or alternatively, locate the diagram in the owner's manual. Keep that handy so that you know how the belt should go on your vehicle.
Locate the tensioner on the front of the engine. This is in the middle of the engine, between the water pump and power steering pump, and has a square slot on it. Insert the breaker bar into the square slot and turn the tensioner counterclockwise to release the tension on the belt. Pull the belt off of the engine and release the breaker bar slowly.
Install the replacement belt onto the crankshaft pulley at the bottom of the engine and route the belt counterclockwise around the pulleys according to the belt routing diagram. Once the belt is wrapped around as much as possible, pull up on the tensioner again with the breaker bar then route the belt around the tensioner. Slowly release the breaker bar which will press the tensioner against the belt and keep it tight.
Verify that the belt is not twisted or kinked in any way prior to starting the vehicle. Once you've made sure that the belt is centered in each pulley and that everything is straight, then you can start the vehicle.
