Engine belts wrap around pulleys and transfer power from one part or system of the engine to another.
Your engine may have a single “serpentine” belt that runs your fan, air conditioning unit, alternator, water pump and power steering or it may have multiple belts running individual systems.
Regardless of the number of belts in the engine, they all need to be checked periodically. Belts should be checked when the engine is cool. Inspect them for cracks and dry rotting. Cracked or rotted belts must be replaced. Push on the belts to see if they “give” more than an inch in any direction – indicating that the belt is loose. A loose belt needs to be tightened.
Regardless of their apparent condition, belts generally should be replaced between 50,000 and 60,000 miles of use.