Skip to main content

Signs of a Bad Belt Tensioner

April 20, 2021

Signs of a Bad Belt Tensioner

Prolong Belt Life by Inspecting the Serpentine Belt, Tensioner and Pulleys Together

Often times during a drive belt change, the tensioner may get overlooked. This can be problematic given the tensioner has a big job to do and likely wears at a similar ratio. The tensioner is responsible for maintaining a constant predetermined pressure on the belt. If the tensioner is not functioning properly, the whole drive system is at risk and the life of the belt is greatly reduced.

Inspecting the Automotive Belt Tensioner

A tensioner and other drive system components should be inspected when the serpentine belt is looked at, typically around 60,000 miles. The serpentine belt, tensioner and pulleys work together as a cohesive unit within the drive system. One cannot function properly without the others also functioning properly. That’s why all three components are considered a system. When one component needs replacing, a mechanic should replace the other components as well for more enhanced performance and product longevity.


Six Signs a Belt Tensioner Needs to be Replaced

1. Tensioner Noise

Listen closely to the tensioner when the engine is running. Remove the belt and check the pulley for free rotation. If you hear noise or feel resistance to turning, this could be the indication of impeding bearing failure. If it spins freely by hand more than two rotations, the grease is gone from the pulley and needs to be replaced.

2. Improper Serpentine Belt Tracking

If the belt is tracking off center, at or off the edge of the pulley, or if the belt flips off the tensioner, this is a clear sign of bushing wear, which causes tensioner misalignment.

3. Tension Loss

If the belt makes a squealing noise or an accessory within the system has stopped working completely, it’s a sign that there is tension loss.

4. Sticking or Notchy Movement

When removing or replacing the belt, check the tensioner torque by moving the tensioner arm from stop to stop. The arm should move smoothly and without hesitant movement.

5. Metal-to-Metal Contact

If there is any metal-to-metal contact between a tensioner’s arm and spring case, it’s a sign of bushing wear.

6. Broken or Cracked Tensioner “Stops”

When removing or replacing the belt, check the tensioner “stops”  located on both the tensioner arm and spring case to see if they are broken.