Dayco 89955 Accessory Drive Belt Tensioner Assembly - Alternator

Accessory Drive Belt Tensioner Overview

Dayco 89955 is an accessory drive belt tensioner assembly for alternator applications on heavy-duty trucks. It is a direct-fit replacement for select Peterbilt and Kenworth models, with fitment covering multiple model years and configurations.

Key Features

• Accessory drive belt tensioner assembly for alternator drive systems
• Direct-fit replacement for select heavy-duty truck applications
• Fits Peterbilt 579, 365, 367, 389, 567, 587, 384, 386, and 388 applications
• Fits Kenworth T660, T680, T700, T800, T880, and W900 applications
• Dayco part number 89955 for catalog and service reference

Detailed Description

Dayco 89955 is built for alternator belt tensioning in accessory drive systems used on select Peterbilt and Kenworth trucks. This tensioner assembly supports proper belt tension control for vehicles such as the Peterbilt 579 and Kenworth T680, helping maintain consistent accessory drive operation across the listed fitments. Use Dayco 89955 when replacing a worn or incorrect alternator belt tensioner assembly on compatible heavy-duty truck applications.

What It Is Used For

• Correcting belt slack in the alternator drive system
• Replacing a tensioner with weak or inconsistent belt control
• Addressing belt noise related to tension loss
• Restoring stable accessory drive performance
• Replacing a damaged or worn Dayco 89955 assembly

Installation Notes and Tips

Verify the vehicle year, model, and alternator application before ordering. Match the existing belt routing and tensioner configuration to the listed fitment for Peterbilt and Kenworth trucks. Inspect the belt and related pulleys during service, and replace any worn components as needed to maintain proper drive system operation.