Dayco 87678 HVAC Heater Hose

Dayco Small I.D. Heater Hose 87678

Dayco 87678 is a small inside diameter heater hose built for HVAC heater circuit service in select import and domestic applications. This 5/8 in. x 5/8 in. EPDM hose is specified for heater-to-engine, heater-to-valve, and valve-to-engine routing where a straight single I.D. hose is required.

Key Features

• EPDM construction for heater hose service
• Black finish for a clean OE-style appearance
• 5/8 in. inside diameter at both ends
• Single I.D. hose design for direct heater circuit routing
• Meets SAE J20R3 Class D-1 and SAE J1684 Type EC specifications
• Dayco Small I.D. Heater Hose line for HVAC hose replacement

Product Details

The Dayco Small I.D. Heater Hose line is designed for heater circuit connections that require a consistent 5/8 in. internal diameter and standard hose routing. Part number 87678 uses EPDM rubber for resistance to heat and coolant exposure in HVAC applications. It is a black, single I.D. hose with no heat shield and no protective sleeve, making it a straightforward replacement for select heater hose runs. This part cross-references Gates 18827 for the same application.

Compatible With 1998-1999 Acura CL, heater to valve; 1991-1994 Mercury Capri, heater to engine; 1989-1991 Pontiac 6000, heater to engine; 1989-1990 Chevrolet Celebrity, heater to engine; 1989-1990 Toyota Tercel, valve to engine; and additional listed applications including 1989 Buick Century, 1989 Oldsmobile Cutlass Ciera, and 1989 Oldsmobile Cutlass Cruiser. Dayco 87678 is a fitment-based replacement for vehicles that use a small I.D. heater hose in the specified routing.

What It Helps Address

• Cracked or hardened heater hose material
• Coolant seepage at heater circuit hose runs
• Restricted heater flow caused by deteriorated hose
• Incorrect hose diameter in heater-to-engine or heater-to-valve routing
• Service replacement for aging HVAC hose assemblies

Installation Notes and Tips

Verify the routing position and inside diameter before installation, especially on applications listed as heater to engine, heater to valve, or valve to engine. Confirm that the hose path matches the original layout and that the connection points are clean before clamping. Because this hose does not include a heat shield or protective sleeve, inspect nearby components for heat exposure and abrasion points during service. Use the vehicle’s specified coolant hose clamps and follow the manufacturer’s cooling system service procedure.

Quality Assurance

Dayco heater hose products are built to meet SAE J20R3 Class D-1 and SAE J1684 Type EC requirements for heater hose service. The 87678 part number is engineered for direct replacement use in the listed applications, including Acura CL, Mercury Capri, and Toyota Tercel fitments.