DAY89440

Includes (sold as a complete tensioner assembly):

• 1× automatic belt tensioner assembly with integrated 74 mm flat pulley (no separate pulley purchase needed).​
• Pre‑loaded flat‑spring mechanism, housed in a sealed cast‑aluminum body, ready for direct bolt‑on replacement.​
• High‑temperature grease in dual bearings and hardened belt running surface for long service life in harsh environments.

Dayco 89440 is a heavy‑duty automatic belt tensioner designed to maintain proper serpentine belt tension on Cummins ISX/ISX15/X15 fan and accessory drive systems in highway tractors and vocational trucks.

Typical ISX15 / X15 Fan & Accessory Drives

• Cummins ISX / ISX15 / X15 engines using OE tensioner 3691282 or equivalents on fan belt circuit (Freightliner, Peterbilt, Kenworth, International, Mack, Volvo, Western Star).​
• Peterbilt 579, Kenworth T680 and other late‑model tractors where the ISX/X15 fan belt is tensioned by 89440‑style automatic tensioner.