Dayco 87959 HVAC Heater Hose - Heater Hose, Heater Inlet or Heater Outlet

Dayco Small I.D. Heater Hose 87959

Dayco 87959 is a branched HVAC heater hose built for vehicles that use multiple small-diameter coolant connections. Made from EPDM and finished in black, it is specified for heater hose, heater inlet, and heater outlet applications across a wide range of Chevrolet and GMC trucks and SUVs.

For Silverado 2500 HD, Sierra 2500 HD, Avalanche, and related HD platforms, this branched heater hose follows the original routing and connection sizes needed for a direct replacement. The Dayco Small I.D. Heater Hose line is focused on OE-style hose configurations for vehicles that require precise branch geometry and multiple end diameters.

Key Features

• Part number: 87959
• Brand: Dayco Small I.D. Heater Hose
• Branched hose design for multi-port heater circuit routing
• EPDM construction for heater hose service
• Black finish
• End diameters: 3/4 in., 1 in., and 3/4 in.
• Built to SAE J20R3 Class D-1 and SAE J1684 Type EC specifications
• Compatible with heater hose, heater inlet, and heater outlet positions listed below

Detailed Description

Dayco 87959 is a branched HVAC heater hose engineered for specific GM truck and SUV applications that use a small I.D. hose layout. The EPDM rubber construction is suited for coolant transfer in heater circuits, while the branched form helps match factory-style hose routing on vehicles such as Chevrolet Silverado 2500 HD, Chevrolet Silverado 3500 HD, GMC Sierra 2500 HD, and GMC Sierra 3500 HD. This part number 87959 is also listed for Chevrolet Avalanche, Silverado 1500 HD, Silverado 2500 HD Classic, and GMC Sierra 1500 HD variants where the original hose uses a branched configuration.

Compatible With: 2014 Chevrolet Silverado 2500 HD, heater hose; 2001-2005 Chevrolet Silverado 2500 HD, heater hose; 2007-2014 Chevrolet Silverado 2500 HD, heater outlet; 2007-2014 Chevrolet Silverado 3500 HD, heater outlet; 2014 GMC Sierra 2500 HD, heater hose; 2001-2006 GMC Sierra 2500 HD, heater hose; 2010-2014 GMC Sierra 2500 HD, heater outlet; 2010-2014 GMC Sierra 3500 HD, heater outlet; 2007-2013 Chevrolet Avalanche, heater inlet.

What It Helps Address

• Cracked or deteriorated heater hose rubber
• Coolant leaks at branched heater hose connections
• Incorrect hose routing after a failed replacement
• Restricted heater flow caused by damaged hose sections
• Fitment issues on GM trucks and SUVs that require small I.D. branched hose geometry

Installation Notes and Tips

Verify the vehicle’s heater hose routing, end diameters, and position before installation. This hose uses 3/4 in. and 1 in. inside diameters at the listed ends, so matching the original configuration is important on Silverado and Sierra applications. Inspect adjoining clamps, fittings, and coolant passages for wear or contamination before installing the new hose. This part number 87959 is intended for the exact applications listed in the fitment data.

Quality Assurance

Dayco manufactures this hose to SAE J20R3 Class D-1 and SAE J1684 Type EC specifications for heater hose service. The Small I.D. Heater Hose product line is built around application-specific hose shapes and sizes for GM cooling and HVAC routing requirements.