6 Signs Your Belt Tensioner Needs Replacing

Serpentine drive systems use a long belt that snakes around most, if not all, of the accessory pulleys. When extra torque is needed, a spring increases the torque that is transmitted to the belt. In a conventional V-Belt system, this torque is limited to static tension due to the belt adjustments having locked centers.

If, when installed, the belt was tensioned insufficiently, or if the belt has stretched or worn through use, it will slip when placed under a load causing poor accessory performance and premature belt failure. If the belt was over-tensioned during its installation, there is risk of premature accessory bearing failure.

A spring-loaded automatic tensioner compensates for the belt’s stretch and wear by maintaining a constant tension on the belt throughout the life of the belt.

Below are signs that your belt tensioner may need to be replaced:


  • Tensioner Makes Noise: While you have the engine running, listen closely to the tensioner. When the engine has been shut off and the belt removed, check the pulley for free rotation. If you can hear a noise or feel resistance to turning this could be an indication that your bearings are failing.
  • Belt Tracks Improperly:  Examine the way the belt tracks and if you notice it is tracking off center, at or off the edge of the pulley, or if the belt flips off the tensioner this could be a sign of tensioner misalignment caused by bushing wear.
  • Loss of Tension: When the belt squeals or an accessory has completely stopped, these are signs of tension loss. 
  • Sticking or Notchy Movement: Check the tensioner torque by applying torque to move the tensioner arm from stop to stop. The arm should move smoothly and without any hesitation.
  • Metal to Metal Contact: Spring bushing or pivot bushing wear can be caused by metal contact between arm and spring case.
    • Busted Tensioner “Stops”: To see if it is broken, check that the tensioner “stops” located both on the tensioner arm and on the spring case.

Dayco Heavy Duty Belt Tensioners at RYDER Fleet Products.

Dayco Gold Label No Slack Heavy Duty Automatic Belt Tensioners are designed for heavy duty diesel engine accessory drive applications.  View our selection of  Dayco belt tensioners and idler pulleys – all available for online ordering. Receive same day shipping on in-stock items and FREE shipping for orders over $250.

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Heavy Duty Truck Parts

RYDER Fleet Products, a BBB A+ rated company, helps transportation industry professionals achieve their on-going goals of safety, reliability and compliance by providing quality aftermarket truck and trailer parts, driver training material, and safety products.

Keep your fleet running smoothly with easy access to the same maintenance tested and road-proven heavy-duty aftermarket truck parts that Ryder® uses on its own fleet. With over 80 years of experience maintaining the most reliable fleet in America, Ryder knows more about parts than anyone else.

Find and buy Dayco parts with confidence – RYDER Fleet Products is an authorized Dayco distributor.

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 Information provided by Dayco.

Dayco Belts and Tensioners

Ryder Fleet Products, Truck Equipment & Parts, Lawrenceville, GA

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