Cummins 3681587 Idler Pulley Assembly

The Cummins 3681587 idler pulley is a critical component in the accessory belt drive system. It guides the serpentine belt and maintains proper tension and alignment for engine accessories such as the alternator, water pump, and fan drive. This pulley is engineered for EPA13 compliant 15-liter platforms including ISX15, QSX15, and X15, as well as the QSC8.3 medium-duty engine. Constructed from high-strength steel with a precision-machined 12-rib profile, the pulley assembly incorporates a sealed bearing designed for high-temperature durability and extended service intervals. It serves as a direct OEM replacement for Cummins part numbers 3680196, 3064404, and 3896408. Primary applications include heavy-duty commercial trucks and construction machinery such as the Hyundai R800LC-7A excavator equipped with Cummins power units.