Gates K120640HD Serpentine Belt - Fan or Fan and Water Pump

Heavy-Duty Micro-V Belt for Fleet Drives

The Gates FleetRunner Heavy Duty Micro-V Belt K120640HD is built for accessory drive systems that see constant load and long service intervals. It uses patented EPDM construction with a distinct green overcord for added durability, flexibility, and belt stability in heavy-duty operation.

For fleet maintenance, this serpentine belt is engineered to help reduce downtime while maintaining consistent drive performance across demanding applications. It is a direct-fit heavy-duty V-ribbed belt for vehicles that require a K-section, 12-rib belt profile.

Key Features

• Gates FleetRunner Heavy Duty Micro-V Belt, part number K120640HD
• Heavy-duty automotive V-ribbed belt with 12 ribs
• EPDM belt material for improved wear resistance and longer service life
• Polyester cord construction for strength and dimensional stability
• OE Improved comparison rating
• Top width: 1.647 in. / 42 mm
• Effective length: 64.07 in. / 1627 mm
• Outside circumference: 64.625 in. / 1641 mm

FleetRunner Belt Line Details

Gates FleetRunner Heavy Duty Micro-V belts are part of Gates’ heavy-duty accessory drive lineup for commercial and fleet service. The K120640HD uses EPDM construction and a green overcord to support durability, flexibility, and belt stability in demanding drive systems where consistent operation matters.

Detailed Description

The Gates K120640HD serpentine belt is a heavy-duty Micro-V belt designed for accessory drive systems that require a K-section, 12-rib profile. Its EPDM construction and polyester cord help maintain belt shape and performance under load, while the OE Improved rating reflects an upgraded replacement standard for service work. This belt is a practical choice for fleet maintenance on vehicles such as Ford F-250 and Ford F-350 applications when the specified belt dimensions match the original equipment requirement.

This part cross-references Dayco 5120640 for the same application.

What This Belt Helps Address

• Squealing or slipping from a worn serpentine belt
• Cracking, glazing, or visible wear on the belt ribs
• Loss of accessory drive consistency under heavy load
• Premature belt replacement in fleet service intervals
• Drive system noise caused by belt deterioration

Installation Notes and Tips

Verify the belt section, rib count, and measured length before installation. Confirm the accessory drive routing and compare the old belt to the K120640HD dimensions: 12 ribs, 1.647-inch top width, and 64.07-inch effective length. Inspect pulleys, tensioners, and idlers for wear before fitting the new belt, and make sure the belt seats fully in each pulley groove.

Compatible With Ford F-250 and Ford F-350 applications when the vehicle uses the specified K-section heavy-duty Micro-V belt dimensions. Fits 2000-2004 Ford F-250, and fits 2000-2004 Ford F-350, where equipped with the matching accessory drive setup.

Quality Assurance

Gates is known for heavy-duty belt engineering, and the FleetRunner line is built for durability, flexibility, and stable performance in demanding fleet use. The K120640HD is manufactured as an OE Improved replacement belt for service applications that require consistent accessory drive operation.