Dayco 73123 Radiator Coolant Hose - Upper

Dayco 73123 Curved Radiator Hose Overview

The Dayco 73123 curved radiator hose is a branched upper coolant hose built for specific BMW cooling system applications. Made from EPDM and finished in black, it is shaped to route coolant through the engine bay while matching the original hose layout for the BMW Z4 and BMW X1.

For buyers searching for a BMW Z4 upper radiator hose or a BMW X1 upper coolant hose, this Dayco hose provides the correct branched configuration and SAE-rated construction for the listed applications.

Key Features

• Brand: Dayco Curved Radiator Hose
• Part number: 73123
• EPDM rubber construction for coolant service
• Black finish
• Branched hose design with multiple end sizes
• SAE J20R4 Class D-1 and SAE J1684 Type EC specification
• Upper radiator hose application
• Compatible with select BMW Z4 and BMW X1 models

Detailed Product Description

Dayco 73123 is a curved radiator coolant hose designed as a branched upper hose for select BMW cooling systems. The EPDM material is commonly used in radiator hose applications because it is suited to coolant exposure and under-hood temperature cycling. This hose features 1 7/16-inch inside diameter ends at the main connections, along with smaller branch connections measuring 5/16 inch and 3/8 inch, supporting the factory-style routing used in the listed vehicles. The Dayco 73123 part number is a direct reference for shoppers comparing replacement upper coolant hoses for BMW Z4 and BMW X1 models.

Dayco’s Curved Radiator Hose line focuses on formed hose shapes that follow OE-style routing, helping maintain proper coolant flow path and fitment in tight engine compartments. This makes the Dayco 73123 a practical choice when replacing a worn or damaged upper radiator hose on the specified BMW applications.

Vehicle Fitment

• Fits 2012-2016 BMW Z4, Upper — Curved Radiator Hose
• Fits 2012-2015 BMW X1, Upper — Curved Radiator Hose

Common Issues This Hose Can Address

• Cracked or hardened upper radiator hose material
• Coolant leaks at the main hose or branch connections
• Collapsed or misshaped hose routing in the cooling system
• Loss of proper coolant circulation through the upper hose path
• Replacement need after heat and age-related rubber wear

Installation Notes and Tips

Verify the hose routing, end diameters, and branch layout against the removed part before installation. Inspect adjoining clamps, fittings, and coolant necks for wear or corrosion, and replace any damaged mating components as needed. After installation, refill the cooling system with the correct coolant and check for leaks at operating temperature.

Quality Assurance

This Dayco radiator coolant hose is manufactured to SAE J20R4 Class D-1 and SAE J1684 Type EC specifications for the listed BMW applications. Part number 73123 is intended for direct replacement use on the confirmed fitment vehicles.