* Age and Wear: Belts are rubber and degrade over time. Exposure to heat, oil, and other fluids accelerates this process. A belt that's several years old is simply more prone to cracking and snapping, regardless of mileage.
* Excessive Wear/Friction: This can be caused by:
* Misalignment of pulleys: If any pulley is even slightly out of alignment, it puts extra stress on the belt, causing premature wear. A bent pulley or a worn pulley bearing are common causes of misalignment.
* Seized or damaged pulley bearings: A bearing that's binding or failing will cause the pulley to rotate unevenly, leading to belt slippage and ultimately breakage.
* Idler pulley failure: These pulleys guide the belt and take up slack. A worn or damaged idler pulley can cause similar problems to a seized main pulley.
* Tensioner failure: The tensioner keeps the belt at the correct tension. A faulty tensioner (either the spring is worn or the pulley is seized) results in insufficient or uneven tension, leading to belt slippage and breakage.
* Glazing or Slipping: If the belt slips repeatedly, it will glaze over and lose its grip. This often happens due to the problems listed above (misalignment, worn pulleys, etc.) but can also be caused by:
* Oil or other fluid leaks: Oil or other fluids on the belt significantly reduce friction, causing slippage.
* Belt itself was defective: While less common, a manufacturing defect in the belt itself could lead to premature failure.
* Over-tightening: Although rare, over-tightening the belt puts excessive stress on it and the bearings, leading to premature failure.
* Under-tightening: Opposite to the above, not enough tension causes slippage and eventual breakage.
To diagnose the *cause* of the broken belt in your Impala, you'll need to:
1. Inspect the belt itself: Look for cracks, glazing, or signs of wear.
2. Visually inspect all pulleys and the tensioner: Look for any damage, binding, excessive play, or signs of bearing failure (noise, rough rotation).
3. Check for fluid leaks: Look for any signs of oil, coolant, or power steering fluid leaks near the belt system.
Replacing just the belt without addressing the underlying cause will almost certainly lead to another broken belt soon after. It's crucial to find and fix the root problem to prevent future issues.
