Keep the serpentine belt tracking true and every engine accessory turning with the Dayco Accessory Drive Belt Tensioner Pulley / Idler Pulley 89112, a heavy-duty grooved pulley for the accessory (main) drive. It rides on the ribbed serpentine belt to guide it and help maintain proper tension so the alternator, fan and other belt-driven accessories keep spinning. It drops in as a direct-fit replacement for many heavy-duty trucks, among them the 1996-2001 Kenworth T800 [6-12.0L], 2004-2008 Kenworth W900 [L6-14.6L] and 2005-2008 Western Star 4900FA [L6-14.6L]. See the Buyer's Guide tab for the full list.
Signs the original pulley may need attention include belt squeal or chirp, a wobbling or rough-spinning pulley, bearing noise, or belt misalignment; diagnose the cause before replacing. Made in the United States.
Interchange: 580100 · 36231 · 36341 · 49164 · 50028 · 900274A · 900566A · 900274 · 900566
This part cross-references / interchanges with the following part numbers:
What does the Dayco 89112 pulley do?
It's a grooved pulley for the accessory (main) drive. It guides the serpentine belt and helps maintain proper tension so the alternator, fan and other accessories keep turning.
Is this an idler or a tensioner pulley?
It's cataloged as both an accessory drive belt tensioner pulley and an idler pulley, so it's listed under both names.
What belt does it work with?
It's an 8-groove pulley matched to 8-rib serpentine belts, with a 74 mm outside diameter and a 37.5 mm width.
What are signs this pulley may need replacing?
Belt squeal or chirp, a wobbling or rough-spinning pulley, bearing noise, or belt misalignment can point to a worn pulley. Diagnose the cause before replacing.
Does it fit my truck?
It fits a wide range of heavy-duty Kenworth, Freightliner, International, Peterbilt, Western Star and Sterling Truck models. Check the Buyer's Guide tab for your exact year, model and engine.
WARNING: These products can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
