Dayco 70646 HVAC Heater Hose - Heater Hose, Heater To Pipe-2 or Heater To Tee

Dayco 70646 Curved Heater Hose Overview

Dayco 70646 is a curved HVAC heater hose built from EPDM for coolant transfer in applications that require a dual inside diameter hose. It is a black hose with a 5/8 in. end on one side and a 3/4 in. end on the other, making it a direct-fit option for select Ford, GMC, Pontiac, Oldsmobile, Lincoln, Mercury, and Chevrolet applications.

Use this Dayco Curved Radiator Hose line part when you need a formed hose profile for tighter routing around engine bay components. The 70646 part number is listed across a wide range of heater and radiator hose applications, including Ford F-150, Ford Bronco, and Ford Mustang fitments.

Key Features

• EPDM construction for heater and coolant hose service
• Dual I.D. hose design with 5/8 in. and 3/4 in. ends
• Curved hose profile for routed installations
• Black finish for a factory-style appearance
• Built to SAE J20R4 Class D-1 and SAE J1684 Type EC specifications
• No heat shield and no protective sleeve

Fitment Details

• Fits 1997-2000 Oldsmobile Silhouette, Heater To Tee, w/Aux. Heater; Curved Radiator Hose
• Fits 1999-2000 Pontiac Montana, Heater To Tee, w/Aux. Heater; Curved Radiator Hose
• Fits 1997-1999 Pontiac Trans Sport, Heater To Tee, w/Aux. Heater; Curved Radiator Hose
• Fits 1997 Ford F-250 HD, N/A, Curved Radiator Hose
• Fits 1988-1997 Ford F-350, N/A, Curved Radiator Hose
• Fits 1980-1981 Ford F-350, N/A, Curved Radiator Hose
• Fits 1972-1978 Ford F-350, N/A, Curved Radiator Hose
• Fits 1980-1996 Ford Bronco, N/A, Curved Radiator Hose
• Fits 1970-1977 Ford Bronco, N/A, Curved Radiator Hose
• Fits 1979-1996 Ford E-150 Econoline, N/A, Curved Radiator Hose
• Fits 1975 Ford E-150 Econoline, N/A, Curved Radiator Hose
• Fits 1979-1996 Ford E-150 Econoline Club Wagon, N/A, Curved Radiator Hose
• Fits 1979-1996 Ford E-250 Econoline, N/A, Curved Radiator Hose
• Fits 1975 Ford E-250 Econoline, N/A, Curved Radiator Hose
• Fits 1987-1996 Ford E-350 Econoline, N/A, Curved Radiator Hose
• Fits 1979-1982 Ford E-350 Econoline, N/A, Curved Radiator Hose
• Fits 1975 Ford E-350 Econoline, N/A, Curved Radiator Hose
• Fits 1987-1996 Ford E-350 Econoline Club Wagon, N/A, Curved Radiator Hose
• Fits 1979-1980 Ford E-350 Econoline Club Wagon, N/A, Curved Radiator Hose
• Fits 1975-1996 Ford F-150, N/A, Curved Radiator Hose
• Fits 1980-1996 Ford F-250, N/A, Curved Radiator Hose
• Fits 1977-1978 Ford F-250, N/A, Curved Radiator Hose
• Fits 1970-1974 Ford F-250, N/A, Curved Radiator Hose
• Fits 1979-1995 Ford Mustang, N/A, Curved Radiator Hose
• Fits 1970-1973 Ford Mustang, N/A, Curved Radiator Hose
• Fits 1991-1993 Chevrolet Lumina, Heater To Pipe-2, Curved Radiator Hose
• Fits 1991-1993 Oldsmobile Cutlass Supreme, Heater To Pipe-2, Curved Radiator Hose
• Fits 1991-1993 Pontiac Grand Prix, Heater To Pipe-2, Curved Radiator Hose
• Fits 1984-1992 Lincoln Mark VII, N/A, Curved Radiator Hose
• Fits 1987-1991 Ford LTD Crown Victoria, N/A, Curved Radiator Hose
• Fits 1991 GMC C1500, N/A, Curved Radiator Hose
• Fits 1991 GMC C2500, N/A, Curved Radiator Hose
• Fits 1991 GMC K1500, N/A, Curved Radiator Hose
• Fits 1991 GMC K2500, N/A, Curved Radiator Hose
• Fits 1987-1991 Mercury Colony Park, N/A, Curved Radiator Hose
• Fits 1971 Mercury Colony Park, N/A, Curved Radiator Hose
• Fits 1978-1991 Mercury Grand Marquis, N/A, Curved Radiator Hose
• Fits 1990-1991 Oldsmobile Cutlass Supreme, N/A, Curved Radiator Hose
• Fits 1989-1990 Buick Regal, N/A, Curved Radiator Hose
• Fits 1981-1990 Lincoln Town Car, N/A, Curved Radiator Hose
• Fits 1977-1988 Ford Thunderbird, N/A, Curved Radiator Hose
• Fits 1975-1988 Mercury Cougar, N/A, Curved Radiator Hose
• Fits 1969-1970 Mercury Cougar, N/A, Curved Radiator Hose
• Fits 1982-1987 Lincoln Continental, N/A, Curved Radiator Hose
• Fits 1980 Lincoln Continental, N/A, Curved Radiator Hose
• Fits 1977-1986 Ford LTD, N/A, Curved Radiator Hose
• Fits 1970-1974 Ford LTD, N/A, Curved Radiator Hose
• Fits 1979-1986 Mercury Capri, N/A, Curved Radiator Hose
• Fits 1979-1983 Ford E-100 Econoline, N/A, Curved Radiator Hose
• Fits 1971-1975 Ford E-100 Econoline, N/A, Curved Radiator Hose
• Fits 1979-1983 Ford E-100 Econoline Club Wagon, N/A, Curved Radiator Hose
• Fits 1970-1983 Ford F-100, N/A, Curved Radiator Hose
• Fits 1983 Ford Thunderbird, Heater Hose, Curved, Dual Diameter; Curved Radiator Hose
• Fits 1980-1983 Lincoln Mark VI, N/A, Curved Radiator Hose
• Fits 1981-1982 Ford E-100 Econoline, N/A, Calif.; Curved Radiator Hose
• Fits 1981-1982 Ford E-100 Econoline Club Wagon, N/A, Calif.; Curved Radiator Hose
• Fits 1981-1982 Ford E-150 Econoline, N/A, Calif.; Curved Radiator Hose
• Fits 1981-1982 Ford E-150 Econoline Club Wagon, N/A, Calif.; Curved Radiator Hose
• Fits 1981-1982 Ford E-250 Econoline, N/A, Calif.; Curved Radiator Hose
• Fits 1981-1982 Ford E-250 Econoline Club Wagon, N/A, Calif.; Curved Radiator Hose
• Fits 1981-1982 Ford E-350 Econoline, N/A, Calif.; Curved Radiator Hose
• Fits 1981-1982 Ford E-350 Econoline Club Wagon, N/A, Calif.; Curved Radiator Hose
• Fits 1978-1982 Ford Fairmont, N/A, Curved Radiator Hose
• Fits 1978-1982 Mercury Marquis, N/A, Curved Radiator Hose
• Fits 1973 Mercury Marquis, N/A, Curved Radiator Hose
• Fits 1971 Mercury Marquis, N/A, Curved Radiator Hose
• Fits 1978-1982 Mercury Zephyr, N/A, Curved Radiator Hose
• Fits 1977-1980 Lincoln Versailles, N/A, Curved Radiator Hose
• Fits 1975-1980 Mercury Monarch, N/A, Curved Radiator Hose
• Fits 1970-1976 Mercury Montego, N/A, Curved Radiator Hose
• Fits 1968-1969 Ford LTD, N/A, Late; Curved Radiator Hose
• Fits 1968-1969 Ford Mustang, N/A, Late; Curved Radiator Hose
• Fits 1968-1969 Mercury Cougar, N/A, Late; Curved Radiator Hose
• Fits 1968-1969 Mercury Montego, N/A, Curved Radiator Hose

What This Hose Helps Address

• Cracked or hardened heater hose material
• Incorrect hose routing in curved applications
• Leaks at dual-diameter hose connections
• Cooling system service on older Ford truck and van platforms
• Heater circuit repairs on select GM and Ford vehicles

Installation Notes

Verify end diameters before installation: 5/8 in. on one end and 3/4 in. on the other. Confirm routing against the vehicle’s original hose path, especially on applications listed as Heater To Tee, Heater To Pipe-2, or California-specific fitments. This part cross-references ACDelco (e.g., 14152S, 14213S) for the same application.

Quality Assurance

Dayco specifies this hose to SAE J20R4 Class D-1 and SAE J1684 Type EC standards, supporting consistent material and dimensional requirements for heater hose service. The EPDM construction is selected for coolant exposure and underhood temperature conditions.