Dayco 71390 Engine Coolant Bypass Hose

Curved Radiator Hose for S10 and Sonoma

Dayco 71390 is a curved radiator hose built for coolant bypass service on select Chevrolet and GMC trucks and SUVs. Made from EPDM rubber, it is shaped for the listed applications and sized with dual inside diameters to match the cooling system connection points.

Key Features

• EPDM construction for coolant hose service
• Black finish
• Dual I.D. hose design with 11/16 in. end 1 inside diameter and 5/8 in. end 2 inside diameter
• Built to SAE J20R4 Class D-1 and SAE J1684 Type EC specifications
• Curved radiator hose profile for the listed vehicle applications
• Dayco part number 71390

Product Details

This Dayco Curved Radiator Hose is an engine coolant bypass hose engineered for the cooling system layouts used on 1987-1993 Chevrolet S10, 1991-1993 GMC Sonoma, 1987-1990 GMC S15, 1987-1988 Chevrolet S10 Blazer, and 1987-1988 GMC S15 Jimmy. The dual I.D. hose design helps match different connection sizes in the coolant circuit, while the EPDM material is commonly used in automotive cooling applications for its resistance to heat and coolant exposure. If you are sourcing a replacement hose for a Chevrolet S10 or GMC Sonoma cooling system, Dayco 71390 provides the correct curved profile for the listed fitments.

This part cross-references ACDelco 16194M and Gates 21774 for the same application.

What It Helps Address

• Coolant leaks from a cracked or aged bypass hose
• Softening, swelling, or deterioration of the original rubber hose
• Improper hose routing on curved cooling system runs
• Loss of coolant flow through the bypass circuit
• Replacement needs on Chevrolet S10 and GMC Sonoma cooling systems

Installation Notes and Tips

Verify the hose routing and end diameters before installation to confirm the correct Dayco 71390 application. Inspect adjoining fittings, clamps, and nearby cooling components for wear or corrosion before installing the new hose. After installation, refill and bleed the cooling system according to the vehicle service procedure and check for leaks at operating temperature.

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 application-specific curved shape support proper fitment on the listed Chevrolet and GMC models.