Belt Tensioner

Belt Tensioner - Mechanical

The only mechanical check that needs to be made is a check for tensioner stick grab or bind.
1. With the engine OFF, check routing of the accessory drive belt.

2. NOTE: The accessory drive belt tensioner spring is very strong and requires substantial force to release.

Using a suitable, commercially available serpentine belt tensioner release tool, release the tension on the belt and detach the accessory drive belt in the area of the tensioner.
3. Using a suitable, commercially available serpentine belt tensioner release tool, move the tensioner from its relaxed position, through its full stroke and back to the relaxed position to make sure there is no stick, grab or bind, and to make sure that there is tension on the tensioner spring.
4. Rotate the tensioner pulley by hand and check for a binding, contaminated or seized condition. Install a new accessory drive belt tensioner if necessary.
5. Inspect the area surrounding the accessory drive belt tensioner for oil leaks or contamination and repair any leaks. Install a new accessory drive belt tensioner as necessary.
6. If the accessory drive belt tensioner meets the above criteria, proceed to testing the tensioner dynamically. If the accessory drive belt tensioner does not meet the above criteria, install a new tensioner.

Belt Tensioner - Dynamics
The accessory drive belt tensioner can be checked dynamically as follows:
1. With the engine running, observe the accessory drive belt tensioner movement. The accessory drive tensioner should move (respond) when the air conditioning clutch cycles (if equipped), or when the engine is accelerated rapidly. If the accessory drive belt tensioner movement is excessive without air conditioning clutch cycling or engine acceleration, check belt rideout. Excessive belt rideout (uneven depth of grooves in the belt) can cause excessive accessory drive belt tensioner movement. Check rideout condition by installing a new belt. If excessive accessory drive belt tensioner movement still exists, install a new accessory drive belt tensioner.