Gates 51999 Premium Molded Coolant Hose 1 3/4" x 1 1/2" x

The Gates 51999 Molded Coolant Hose is a pre-shaped radiator replacement part designed to handle standard engine cooling demands. Built for automotive cooling systems requiring a specific molded contour, it provides a direct-fit connection that helps ensure sealed conditions without forcing a straight hose into an unnatural bend.

Construction centers around an EPDM inner tube paired with synthetic fiber knit reinforcement and an outer EPDM cover. This layered build resists ozone, heat, and chemical coolant exposure. The hose is specifically engineered to resist electrochemical degradation, which is the leading cause of hose failure, while preventing internal collapse under vacuum conditions.

In terms of operating limits and industry standards, the hose functions within a temperature range of -40 degrees Fahrenheit to +257 degrees Fahrenheit (-40 degrees Celsius to +125 degrees Celsius). It meets SAE 20R3 EC Class D1 specifications for inner diameters under 25mm (1 inch) and SAE 20R4 EC Class D1 for inner diameters of 25mm (1 inch) and over.

Be aware of specific application limits before purchasing. This hose is strictly for engine coolant systems and must not be used for fuel or oil transfer. Additionally, Gates recommends installing fresh clamps each time a new coolant hose is installed to maintain proper sealing.

Verdict: The Gates 51999 is a reliable, direct replacement for compatible cooling loops that need resistance to heat, vacuum collapse, and electrochemical breakdown. It is a solid pick for anyone completing routine radiator maintenance, provided you also supply new clamps.

• Dimensions: 1 3/4 inch x 1 1/2 inch
• Tube Material: EPDM
• Reinforcement: Synthetic fiber knit
• Cover Material: Heat-, ozone-, and chemical coolant-resistant EPDM
• Temperature Range: -40 Deg. F to +257 Deg. F (-40 Deg. C to +125 Deg. C)
• Standards Met: SAE 20R3 EC Class D1 (< 25mm ID), SAE 20R4 EC Class D1 (>= 25mm ID)

A great fit if you:

• Need a pre-shaped 1 3/4 inch by 1 1/2 inch radiator coolant hose.
• Require a hose rated for temperatures between -40 and +257 degrees Fahrenheit.
• Want EPDM construction engineered to resist electrochemical degradation and vacuum collapse.

Consider something else if you:

• Need a line for transferring fuel or motor oil.
• Prefer a universal straight hose rather than a pre-shaped molded design.

Can this hose be used for fuel or oil lines?
No. The manufacturer cautions specifically against using this hose for fuel or oil transfer applications.

What is the operating temperature range?
The hose is rated to function in temperatures ranging from -40 degrees Fahrenheit to +257 degrees Fahrenheit (-40 degrees Celsius to +125 degrees Celsius).

Do I need to buy new clamps for installation?
Gates recommends replacing the clamps each time a new coolant hose is installed to ensure a proper fit and seal.