Serpentine belts are designed to last 60,000 to 90,000 miles before replacement. Manufacturers recommend inspecting them every six months or at every oil change. This belt drives every accessory on the vehicle, and a break strands the vehicle.
When inspecting the belt, owners should look for cracks or glazed spots on the ribbed side of the belt. Inspect the flat side of the belt for signs of oil leaks that cause the water pump to slip, affecting coolant circulation and indicating other engine problems. Belts begin to show cracks about halfway through their life. Once the distance between the cracks decreases to 1/8 inch or less, the belt requires replacement.