A drive belt tensioner is a pulley mounted on a spring mechanism or adjustable pivot point that is used to keep tension on the engine belts. Spring tensioners are designed to tension automatically while the pivot design types can be adjusted manually. Both are used to keep tension on the engine serpentine belts so that they can drive the various engine accessories.

When the tensioner has an issue, it can affect the how the belts drive the pulleys which can affect the performance and functionality of the vehicle. Usually a bad or failing tensioner will produce a few symptoms that can alert the driver of a potential problem that should be serviced.

1. Grinding or squeaking noise from the belts or tensioner

The most common symptom of a bad or failing drive belt tensioner is noise from the belts or tensioner. If the tensioner is loose the belts may squeak or squeal, especially when the engine is first started. It is also possible for the tensioner pulley or bearing to wear out, in which case the vehicle will produce a grinding noise from the pulley.

2. Unusual belt wear

Another symptom of a potential problem with the drive belt tensioner is unusual belt wear. If the drive belt tensioner pulley has any sort of issue it can cause unusual and accelerated wear on the belt. A bad pulley can cause fraying on the edges of the belt, and in severe cases can even cause it to break.

3. Belt-driven accessories fail

Another symptom of bad or failing drive belt tensioner is failure of the belt driven accessories. Many of the engine’s accessories, such as the alternator, water pump, and AC compressor, can be belt driven. A seized or loose drive belt tensioner can cause the belt to snap, which will disables those accessories and can cause problems such as overheating, a dead electrical system and battery, or a disabled AC system. Usually a belt that has failed because of the tensioner will have to be replaced, along with the tensioner, in order to restore full functionality to the vehicle.

A drive belt tensioner is an important component as it is what keeps the belt properly tensioned so that it can properly drive the vehicle’s accessories. If you suspect that your drive belt tensioner may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if it should be replaced.

This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Drive Belt Tensioner and was authored by Ed Ruelas.


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