Dayco 88507 HVAC Heater Hose - Expansion Tank To Heater Core

Dayco Small I.D. Heater Hose for BMW Cooling Systems

Dayco 88507 is a Small I.D. Heater Hose built for HVAC heater hose service in select BMW cooling system layouts. It connects the expansion tank to the heater core and uses EPDM construction with a black finish for a direct-fit replacement in the specified applications.

Compatible With 1998-2000 BMW 528i, expansion tank to heater core; 2001-2003 BMW 525i, expansion tank to heater core; and 2001-2003 BMW 530i, expansion tank to heater core. This Dayco heater hose is identified by part number 88507.

Key Features

• Brand: Dayco Small I.D. Heater Hose
• Part number: 88507
• EPDM hose material for HVAC heater hose service
• Black finish
• Single I.D. hose design
• End 1 inside diameter: 5/8 in.
• End 2 inside diameter: 7/8 in.
• SAE J20R3 Class D-1 and SAE J1684 Type EC specification
• Length: 27 1/2 in.

Product Details

Dayco 88507 is part of the Small I.D. Heater Hose line, a product line focused on heater hose routing where compact inside diameters and OE-style fit are required. This hose is built from EPDM and follows SAE J20R3 Class D-1 and SAE J1684 Type EC standards, making it a practical replacement for the expansion tank to heater core connection on the listed BMW 5 Series models. The hose measures 27 1/2 inches in length and uses different end diameters to match the application: 5/8 inch on one end and 7/8 inch on the other.

For BMW 528i, BMW 525i, and BMW 530i applications, Dayco 88507 provides the correct routing profile for the heater circuit connection shown in the fitment data. The part number 88507 is a useful reference when matching the hose to the vehicle’s HVAC hose layout.

Common Issues This Hose Can Address

• Cracked or hardened heater hose material
• Coolant seepage at the expansion tank to heater core connection
• Restricted heater flow from deteriorated hose internals
• Incorrect hose length or end diameter during replacement
• Loss of heater performance caused by a damaged hose section

Installation Notes and Tips

Verify the hose routing and end diameters before installation, especially on BMW 528i, 525i, and 530i models with the expansion tank to heater core connection. Inspect adjoining clamps, fittings, and nearby coolant components for wear before reassembly. Confirm the hose is seated fully and routed without kinks or twist to maintain proper coolant flow.

Quality Assurance

Dayco manufactures this hose to SAE J20R3 Class D-1 and SAE J1684 Type EC specifications for heater hose applications. The EPDM construction and application-specific sizing support consistent fitment for the listed BMW models. No warranty information was provided in the product data.