Radiator Inlet Fitting 1-5/8in x -20AN

The Radiator Inlet Fitting 1-5/8in x -20AN from Northern Radiator is a precision adapter engineered for high-performance cooling system plumbing in custom and modified vehicles. This straight-thread fitting connects AN-line radiator hoses to inlet ports, serving builders who demand reliable, leak-free fluid transfer in engine builds ranging from street machines to competition applications. Whether you're installing a custom radiator, upgrading to larger-diameter hose routing, or fabricating a custom cooling circuit, this adapter provides the mechanical foundation your system requires.

Constructed from clear anodized aluminum, the Radiator Inlet Fitting features a 20 AN male O-ring boss design on both ends, eliminating the need for traditional crush washers and enabling positive, repeatable seal integrity across thermal cycles. The 1-5/8-inch dimension accommodates standard radiator inlet port sizes, while the straight-thread geometry simplifies installation in tight engine compartments without requiring offsetting or elbow adapters. Anodized aluminum resists corrosion in coolant environments and provides weight savings critical in performance builds, while the O-ring boss system—superior to JIC flare fittings—delivers superior vibration resistance and eliminates micro-leaks common in high-RPM applications.

Builders integrating custom aluminum radiators, engine conversions, or remote-mounted cooling components will find this fitting indispensable for establishing secure connections between hard-line plumbing and flex hose runs. Its compact 3 x 2.35 x 6.05-inch footprint fits confined spaces without compromising accessibility for wrench clearance. Compatible with all -20AN hose and line systems, this adapter pairs seamlessly with braided stainless hose, push-lock fittings, and modular radiator configurations—making it the go-to choice for serious fabricators and professional hot rod shops demanding OEM-equivalent reliability in custom cooling architecture.