Dayco 87780 Engine Coolant Bypass Hose

Dayco Small I.D. Heater Hose for Ford Taurus

The Dayco 87780 is a branched engine coolant bypass hose built for small inside-diameter heater hose routing in select Ford and Mercury applications. Made from EPDM and finished in black, it supports coolant flow between the passenger side and engine on listed vehicles.

Key Features

• Dayco Small I.D. Heater Hose line for targeted coolant hose replacement
• EPDM construction for coolant-system service
• Branched hose design with 5/8 in. end 1 I.D., 3/4 in. end 2 I.D., and 5/8 in. end 3 I.D.
• Black finish for a clean OE-style appearance
• Built to SAE J20R3 Class D-1 and SAE J1684 Type EC specifications
• Part number 87780 for easy lookup and ordering

Detailed Description

Dayco 87780 is an engine coolant bypass hose in the Small I.D. Heater Hose product line, made for applications that require a branched hose layout and precise small-diameter connections. The EPDM rubber construction is suited for coolant routing, while the SAE J20R3 Class D-1 and SAE J1684 Type EC specifications provide a clear reference for hose performance requirements. This hose is listed for 1996-1999 Ford Taurus and 1998-1999 Mercury Sable applications, with passenger side to engine routing noted in the fitment data. If you are replacing a worn Ford Taurus heater hose or sourcing a Mercury Sable coolant bypass hose, Dayco 87780 gives you a direct match to the listed configuration.

This part cross-references Ford F6DZ-18472-AA and Motorcraft KM4491 for the same application.

What It Is Used For

• Replacing a cracked or leaking coolant bypass hose
• Restoring heater hose routing on the passenger side to engine path
• Addressing coolant seepage at branched hose connections
• Correcting soft, swollen, or heat-aged EPDM hose sections
• Maintaining proper coolant circulation in listed Ford Taurus and Mercury Sable models

Installation Notes and Tips

Verify the hose routing, end diameters, and branch layout against the removed part before installation. Inspect adjoining clamps, fittings, and nearby coolant lines for wear, corrosion, or residue that could indicate a broader cooling-system issue. After installation, refill and bleed the cooling system according to the vehicle service procedure and check for leaks at operating temperature.

Quality Assurance

Dayco manufactures this hose to meet the listed SAE specifications and application requirements for the identified Ford Taurus and Mercury Sable fitments. The part number 87780 is cataloged for direct reference when matching the correct coolant bypass hose configuration.