{"product_id":"dayco-5120985-serpentine-belt-fan-or-fan-and-air-conditioning","title":"Dayco 5120985 Serpentine Belt - Fan or Fan and Air Conditioning","description":"\u003ch2\u003eDayco 5120985 Serpentine Belt Overview\u003c\/h2\u003e\u003cp\u003eThe Dayco 5120985 serpentine belt is a K-section accessory drive belt built for long service in demanding engine bays. It uses EPDM rubber with aramid reinforcement to help maintain tension stability and resist wear across a wide temperature range.\u003c\/p\u003e\u003cp\u003eCompatible With heavy-duty truck and diesel applications that use a 12-rib, K-section belt profile, including Freightliner, Cummins, and Navistar platforms. The Dayco 5120985 is also cross-referenced to common OE-style replacement numbers for the same application.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eEPDM construction with aramid reinforcement for durability\u003c\/li\u003e\n\u003cli\u003e12-rib, straight-rib design for accessory drive engagement\u003c\/li\u003e\n\u003cli\u003eK-section profile with a 1.66 in top width\u003c\/li\u003e\n\u003cli\u003eEffective length: 98.50 in (2501.90 mm)\u003c\/li\u003e\n\u003cli\u003eOutside circumference: 99.16 in (2518.67 mm)\u003c\/li\u003e\n\u003cli\u003eBlack belt finish\u003c\/li\u003e\n\u003cli\u003eOperating temperature range: -45°F to 212°F\u003c\/li\u003e\n\u003cli\u003eBuilt to SAE J1459 and SAE J2432 standards\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eDetailed Description\u003c\/h2\u003e\u003cp\u003eDayco 5120985 is a serpentine belt for accessory drive systems that require a 12-rib K-section belt with a 98.50-inch effective length. The EPDM compound is paired with aramid reinforcement to support consistent belt performance under heat, cold, and continuous engine loading. This makes it a practical choice for diesel and commercial-duty service where belt stability matters.\u003c\/p\u003e\u003cp\u003eFor buyers searching for a Dayco 5120985 serpentine belt, this part cross-references Gates K120985HD and ACDelco K120985HD for the same application. It is a direct-fit style replacement for select Freightliner, Cummins, and Navistar equipment that uses this belt specification.\u003c\/p\u003e\u003ch2\u003eWhat It Helps Address\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eSquealing or slipping accessory drive belts\u003c\/li\u003e\n\u003cli\u003eCracking, glazing, or rib wear on the existing belt\u003c\/li\u003e\n\u003cli\u003eLoss of belt tension from age and heat cycling\u003c\/li\u003e\n\u003cli\u003eAccessory drive noise from an aging serpentine belt\u003c\/li\u003e\n\u003cli\u003eService replacement for a worn 12-rib diesel belt\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eInstallation Notes and Tips\u003c\/h2\u003e\u003cp\u003eVerify the belt length, rib count, and K-section profile against the original belt before installation. Inspect pulleys, tensioners, and idlers for wear or misalignment, since those conditions can shorten belt life. Confirm routing against the vehicle’s belt diagram during service.\u003c\/p\u003e\u003cp\u003eFits 2006-2011 Freightliner, model-specific applications using this belt specification. Fits 2006-2011 Cummins, model-specific applications using this belt specification. Fits 2006-2011 Navistar, model-specific applications using this belt specification.\u003c\/p\u003e\u003ch2\u003eQuality Assurance\u003c\/h2\u003e\u003cp\u003eDayco manufactures this belt to SAE J1459 and SAE J2432 standards, with EPDM and aramid reinforcement selected for durability in accessory drive service. The part number 5120985 is listed with OE-style interchange references for application matching.\u003c\/p\u003e","brand":"Dayco","offers":[{"title":"Default Title","offer_id":52744351613109,"sku":"BCWL-5120985","price":83.1,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0628\/1442\/1173\/files\/DY_5120985_Fro.jpg?v=1782624562","url":"https:\/\/www.partcatalog.com\/products\/dayco-5120985-serpentine-belt-fan-or-fan-and-air-conditioning","provider":"PartCatalog","version":"1.0","type":"link"}