Dayco 70785 Engine Coolant Bypass Hose

Dayco 70785 Curved Radiator Hose Overview

Dayco 70785 is an engine coolant bypass hose built for select Chevrolet and GMC truck and van applications. Made from EPDM and finished in black, this curved radiator hose uses a single 5/8 in. inside diameter at both ends for a direct replacement-style coolant connection.

Compatible With Chevrolet P20, P30, C20, C30, K20, K30, P10, G20, G30 and GMC P2500, P3500, C2500, C3500, K2500, K3500, P1500, C1500, G25, G35 applications, Dayco 70785 supports a wide range of classic GM cooling system service needs. This part cross-references Gates 19106 for the same application.

Key Features

• EPDM construction for coolant-system service
• Black finish for a clean OE-style appearance
• Single I.D. hose with 5/8 in. inside diameter at both ends
• Meets SAE J20R4 Class D-1 and SAE J1684 Type EC specifications
• Curved radiator hose profile for select GM truck and van routing
• Dayco part number 70785 for easy identification

Detailed Product Description

Dayco’s Curved Radiator Hose line focuses on replacement cooling hoses for vehicles that need accurate routing and dependable coolant transfer. Part number 70785 is an engine coolant bypass hose formed in EPDM to handle underhood coolant exposure while maintaining the curved shape needed for the listed Chevrolet and GMC applications. The 5/8 in. end diameters and single I.D. design make it a straightforward service part for cooling system repairs on older GM platforms.

Use Dayco 70785 when servicing cooling system plumbing on 1975-1989 Chevrolet P10, P20, P30, C20, C30, K20, K30, G20, G30 and related GMC P1500, P2500, P3500, C1500, C2500, C3500, K1500, K2500, K3500, G25, G35, and Suburban applications. The fitment coverage includes Chevrolet and GMC truck, van, and Suburban models across the 1975-1989 model years.

What This Hose Helps Address

• Coolant bypass hose cracking or age-related hardening
• Leaks at a 5/8 in. hose connection
• Improper hose routing in curved cooling system runs
• Cooling system service on older Chevrolet and GMC trucks and vans
• Replacement of a worn or deteriorated engine coolant hose

Installation Notes and Tips

• Verify hose routing and end diameters before installation.
• Inspect adjoining fittings, clamps, and coolant passages for wear or corrosion.
• Drain coolant as needed before removing the existing hose.
• Confirm the hose follows the original curved path without kinks or twist.
• After installation, refill and bleed the cooling system according to vehicle service procedures.

Quality Assurance

Dayco 70785 is built to SAE J20R4 Class D-1 and SAE J1684 Type EC specifications, supporting consistent material and performance requirements for cooling system hose service.