S-Type (X200) V8-4.2L (2005)
Drive Belt Tensioner: Testing and Inspection
Dynamic Testing
Accessory drive belt tensioner or supercharger belt tensioner-dynamic
The accessory drive belt tensioner or supercharger belt can be checked dynamically as follows:
1. With the engine running, observe drive belt tensioner movement, the accessory drive belt tensioner should move (respond) when the air
conditioning clutch cycles (if equipped), both the accessory drive belt tensioner and supercharger belt tensioner should move (respond) when the
engine is accelerated rapidly. If the drive belt tensioner movement is erratic without air conditioning clutch cycling or engine acceleration, a pulley
or shaft is probably bent, or a pulley is distorted. Excessive drive belt ride out (uneven depth of grooves in the drive belt) can cause excessive
drive belt tensioner movement. Check condition by installing a new accessory drive belt.
2. With the engine off, check routing of the accessory drive belt.
3. Inspect the drive belt tensioner wear indicator to confirm the accessory drive belt is within operating range. Install a new accessory drive belt or
supercharger belt if necessary.
4. Rotate the accessory drive belt tensioner and check for a binding or seized condition. Install a new accessory drive belt tensioner or supercharger
belt tensioner if necessary.