You can't simply adjust the tension by turning a bolt or similar. If the belt is slipping, the problem is usually one of the following:
* Worn or failing tensioner: The automatic tensioner itself might be failing. It might be seized or worn out, unable to maintain proper tension. This is a common cause.
* Worn belt: The serpentine belt itself might be cracked, glazed, or worn, reducing its grip.
* Pulley problems: One or more of the pulleys (alternator, power steering pump, A/C compressor, etc.) might be seized, misaligned, or have worn bearings. This will increase belt wear and cause slipping.
If your belt is slipping, you need to have a mechanic diagnose the underlying issue. Simply replacing the belt without addressing the cause of the slipping will likely result in a quickly worn-out new belt. Ignoring the problem can lead to more serious damage to related components.
