Dayco 87791 HVAC Heater Hose - Heater To Water Pump

Dayco 87791 Heater Hose for Ford Super Duty Applications

Dayco 87791 is a Small I.D. Heater Hose built for heater-to-water-pump routing on select Ford heavy-duty trucks and SUV applications. It uses EPDM construction with a black finish and a protective sleeve for added abrasion resistance in the engine bay.

Key Features

• EPDM heater hose construction for coolant transfer in HVAC systems
• 5/8 in. inside diameter at both ends
• Single I.D. hose design for heater-to-water-pump routing
• Protective sleeve included for added surface protection
• Meets SAE J20R3 Class D-1 and SAE J1684 Type EC specifications
• Black finish for a clean OE-style appearance

Product Details

This Dayco Small I.D. Heater Hose is engineered for Ford Excursion and Ford F-250 Super Duty / F-350 Super Duty heater hose service where a quick-connect style connection is used. The 87791 part number is a direct-fit style replacement for the specified heater-to-water-pump location, with 5/8-inch end diameters and EPDM material selected for coolant and heat exposure in HVAC hose applications. This part cross-references Duralast E87791 for the same application.

As part of Dayco’s Small I.D. Heater Hose line, this hose focuses on compact routing and OE-style fitment for smaller coolant passages in the heating circuit. The protective sleeve adds an extra layer between the hose and nearby engine components, helping maintain hose integrity in tight underhood spaces. Dayco 87791 is also referenced by Ford part numbers F81H-18K580-M and XC3H-18K580-JA.

What It Helps Fix

• Coolant leaks at the heater hose connection
• Cracked or hardened heater hose material
• Restricted coolant flow in the heater circuit
• Damaged hose from abrasion in tight engine-bay routing
• Loss of heater performance caused by a failing hose

Installation Notes

• Fits 2000-2003 Ford Excursion, heater to water pump, w/quick connect; small I.D. heater hose
• Fits 1999-2003 Ford F-250 Super Duty, heater to water pump, w/quick connect; small I.D. heater hose
• Fits 1999-2003 Ford F-350 Super Duty, heater to water pump, w/quick connect; small I.D. heater hose
• Verify hose routing, connection style, and end diameter before installation
• Inspect adjoining clamps, fittings, and coolant condition during service

Quality Assurance

Dayco manufactures this hose to SAE J20R3 Class D-1 and SAE J1684 Type EC specifications for HVAC heater hose applications. The EPDM construction and protective sleeve support consistent performance in the specified Ford Excursion and Ford Super Duty fitments.