Dayco 71663 Radiator Coolant Hose - Upper

Dayco Curved Radiator Hose 71663

Dayco 71663 is a curved radiator coolant hose built for upper cooling-system routing on select BMW applications. Made from EPDM rubber with a black finish, it uses a single I.D. hose design and 1 19/32-inch inside diameters at both ends for a direct replacement-style fit.

This Dayco Curved Radiator Hose line is engineered for cooling-system service where a formed hose is needed to follow the factory path without unnecessary stress at the connection points. Part number 71663 is listed for multiple BMW 3 Series, 5 Series, M3, and Z3 applications.

Key Features

• EPDM construction for radiator coolant service
• Black curved hose profile for upper radiator routing
• 1 19/32-inch inside diameter at both ends
• Single I.D. hose design
• Meets SAE J20R4 Class D-1 and SAE J1684 Type EC specifications
• No heat shield and no protective sleeve
• Fits upper hose positions on listed BMW applications

Detailed Description

Dayco 71663 is a radiator coolant hose for BMW cooling systems that require a curved upper hose configuration. The EPDM rubber construction is selected for coolant exposure, while the formed shape helps maintain the factory routing path. This hose is listed for 1992-1995 BMW 320i, 325i, and 325is; 1994-1999 BMW M3; 1996-1999 BMW 328i and 328is; 1997-2000 BMW 528i; 1997-2002 BMW Z3; 1998-1999 BMW 323i and 323is; 2001-2003 BMW 525i and 530i; and 2001-2006 BMW M3, upper. This part number 71663 also cross-references Duralast C71663 for the same application.

What It Helps Fix

• Coolant leaks from a cracked or aged upper radiator hose
• Softening, swelling, or collapse in the original hose
• Improper hose routing caused by a deformed curved hose
• Cooling-system service needs on BMW upper hose applications
• Loss of coolant flow from a restricted or deteriorated hose

Installation Notes and Tips

Verify the hose end inside diameter and routing before installation. This hose is listed for upper radiator positions and is noted for BMW M3 applications without Quick Connect. Inspect adjoining fittings, clamps, and coolant condition before reassembly, and confirm the hose follows the original curved path without twist or kinks.

Quality Assurance

Dayco 71663 is built to SAE J20R4 Class D-1 and SAE J1684 Type EC requirements for radiator hose service. The EPDM material and formed construction support consistent fitment across the listed BMW applications, including BMW M3, 525i, 530i, and Z3 upper hose locations.