Dayco 70843 Radiator Coolant Hose - Lower or Upper

Curved radiator hose for select Honda and Mazda applications

Dayco Curved Radiator Hose 70843 is a molded EPDM coolant hose built for specific upper and lower radiator hose applications. It is shaped to follow the factory routing on select Honda Civic, Mazda Protege, and Mazda Protege5 models for a direct-fit replacement.

Dayco’s Curved Radiator Hose line focuses on OE-style hose geometry and material selection for cooling system service. Part number 70843 is a single I.D. hose with 1 1/16-inch inside diameter at both ends and a black EPDM construction that meets SAE J20R4 Class D-1 and SAE J1684 Type EC requirements.

Key features

• Brand: Dayco Curved Radiator Hose
• Part number: 70843
• EPDM rubber construction for coolant service
• Single I.D. hose with 1 1/16-inch inside diameter at both ends
• Black finish
• Curved hose profile for factory-style routing
• Meets SAE J20R4 Class D-1 and SAE J1684 Type EC specifications
• No heat shield and no protective sleeve

Detailed description

This radiator coolant hose is built for cooling system replacement where the original hose follows a curved path between the engine and radiator. The molded shape helps maintain proper routing on 1999-2003 Mazda Protege lower radiator hose applications, 2002-2003 Mazda Protege5 lower radiator hose applications, and 1975-1979 Honda Civic upper radiator hose applications. If you are sourcing a Dayco 70843 replacement for a Mazda Protege or Honda Civic cooling system repair, this hose matches the listed fitment and dimensions.

This part cross-references Gates 21279 and NAPA 7990 for the same application.

Vehicle fitment

• Fits 1999-2003 Mazda Protege, lower
• Fits 2002-2003 Mazda Protege5, lower
• Fits 1975-1979 Honda Civic, upper

What this hose helps address

• Coolant leaks from a cracked, swollen, or aged radiator hose
• Soft hose collapse under normal cooling system pressure
• Improper hose routing after radiator or engine service
• Heat-related deterioration in an original EPDM hose
• Loss of coolant flow caused by a damaged curved hose section

Installation notes and tips

Verify end diameters, hose routing, and position before installation. Inspect hose clamps, radiator necks, and adjoining coolant pipes for wear or corrosion before reassembly. Drain the cooling system as needed, route the hose without twisting, and confirm there is no interference with moving or hot engine components.

Quality assurance

Dayco manufactures this hose to SAE J20R4 Class D-1 and SAE J1684 Type EC specifications for coolant hose service. The EPDM construction and molded profile support consistent fitment on the listed Honda Civic, Mazda Protege, and Mazda Protege5 applications.