Static check
The accessory drive belt tensioner can be checked statically as described below.
Disconnect the accessory drive belt in the area of the belt tensioner.
Using the special tool, move the belt tensioner from its free position to full piston travel and back to the free position to make sure there is no binding or sticking and make sure the belt tensioner spring is under tension.
Rotate the accessory drive belt tensioner pulley and check it for damage and free rotation and alignment. Install a new tensioner if necessary.
Inspect the area around the accessory drive belt tensioner for grease or other contamination. Repair any leaks before installing a new tensioner. If the belt tensioner is dirty, do not attempt to clean it as the damping mechanism located inside may be damaged. Install a new tensioner if necessary.
If the accessory drive belt tensioner meets the above criteria, proceed to the dynamic test. If the accessory drive belt tensioner does not meet the above criteria, install a new tensioner.
Dynamic Check
The accessory drive belt tensioner can be checked dynamically by following the sequence below.
With the engine running, observe the movement of the belt tensioner. The tensioner must move (to react) when the engine accelerates hard or when the A/C clutch cycles. If the movement of the tensioner is not constant without engine acceleration or cycling of the A/C clutch, it is possible that the pulley or shaft is deformed or deviated from the standard shape, or the damping mechanism located inside the tensioner is damaged. Excessive accessory drive belt run (uneven depth of grooves in the accessory drive belt) could be causing the belt tensioner to move too much. Check by installing a new accessory drive belt.