Gates 18421 HVAC Heater Hose - Pipe To Pipe or Pipe-4 To Pipe-5

Gates Molded Heater Hose 18421 Overview

The Gates 18421 molded heater hose is an OEM-style coolant hose built for tight engine bays where a straight hose will not route correctly. With a 0.5 in. (13 mm) inside diameter at both ends and an 8 in. (203 mm) centerline length, it is sized for select Toyota, Honda, Acura, and Isuzu applications that require a factory-shaped hose path.

Gates Molded Heater Hose line products are formed to match original routing needs in compact engine compartments. This hose is approved for coolant, water, air, and marine applications, making it a practical replacement for heater and coolant routing where molded shape and fit are important.

• Part number: 18421
• EPDM construction for coolant and heater hose service
• 0.5 in. / 13 mm inside diameter at both ends
• 8 in. / 203 mm centerline length
• Molded, factory-style hose shape for tight routing
• Approved for coolant, water, air, and marine applications

Vehicle Fitment

• Fits 2002-2004 Isuzu Axiom, N/A; protective sleeve required; Molded Heater Hose
• Fits 2000-2004 Isuzu Rodeo, N/A; protective sleeve required; Molded Heater Hose
• Fits 1998 Isuzu Rodeo, N/A; protective sleeve required; Molded Heater Hose
• Fits 2001-2003 Isuzu Rodeo Sport, N/A; protective sleeve required; Molded Heater Hose
• Fits 1998-2002 Honda Passport, N/A; protective sleeve required; Molded Heater Hose
• Fits 1998-2002 Isuzu Trooper, N/A; Molded Heater Hose
• Fits 1999-2001 Isuzu VehiCROSS, N/A; Molded Heater Hose
• Fits 2000 Isuzu Amigo, N/A; protective sleeve required; Molded Heater Hose
• Fits 1998 Isuzu Amigo, N/A; protective sleeve required; Molded Heater Hose
• Fits 1998-1999 Acura SLX, N/A; protective sleeve required; Molded Heater Hose
• Fits 1999 Isuzu Amigo, N/A; Molded Heater Hose
• Fits 1999 Isuzu Rodeo, N/A; Molded Heater Hose
• Fits 1998 Toyota Celica, Pipe-4 To Pipe-5; Molded Heater Hose
• Fits 1994 Toyota Celica, Pipe-4 To Pipe-5; Molded Heater Hose
• Fits 1991-1995 Toyota MR2, Pipe To Pipe; radiator and HVAC compatible coolant and heater hose; Molded Heater Hose
• Fits 1990-1993 Toyota Celica, Pipe To Pipe; Molded Heater Hose

Common Replacement Uses

• Replacing a cracked or softened heater hose in a molded routing application
• Restoring coolant flow through a tight engine compartment hose path
• Addressing leaks at a hose section with the correct formed shape
• Replacing a hose that no longer holds its original bend or alignment
• Servicing heater or coolant lines on select Toyota MR2, Toyota Celica, and Isuzu models

Installation Notes

Verify hose routing, end diameters, and centerline length before installation. Some listed applications require a protective sleeve, so confirm the vehicle-specific note before service. This hose is molded for direct routing on the listed applications, and the correct orientation matters for proper fit on Toyota Celica, Toyota MR2, Honda Passport, and Isuzu Rodeo platforms.

This part cross-references Continental (e.g., 63347, 63963) for the same application.

Quality Assurance

Gates manufactures this molded heater hose as an OEM-style replacement using EPDM material and factory-shaped dimensions for the listed applications. Part number 18421 is built to match the routing demands of compact engine compartments and the fitment requirements shown above.