ACDelco Molded Branched Heater Hose 18221L — Black, GM OE-Style Direct-Fit EPDM

The ACDelco Professional 18221L is a factory-molded, GM OE-style branched heater hose engineered for direct-fit coolant and heater connections in modern tight engine bays.

Designed as a premium aftermarket replacement, this molded heater hose mirrors GM original equipment shapes to simplify installation and restore proper coolant routing. Constructed from a proprietary EPDM rubber blend, the hose resists electrochemical degradation and stays flexible across a broad temperature range, making it suitable for coolant, water, and air applications — including many marine uses. It is not rated for fuel or oil transfer.

How does this molded branched heater hose make installation easier?

The 18221L is formed to the same contours as GM OE parts so it installs without twisting, buckling, or excessive stress at connection points. That precise shaping reduces the need for adjustments during replacement and shortens labor time.

• Factory-molded GM OE-style shape for direct-fit installation
• Protective sleeve where required to match original fit and routing
• Minimizes bending and strain at hose ends to prevent leaks

What materials and temperature range does this hose use and support?

ACDelco uses a proprietary EPDM rubber blend for flexibility and durability. The hose is temperature-rated from −40°F to 275°F (−40°C to 135°C), suitable for standard engine coolant systems and many marine cooling applications.

• Proprietary EPDM composition for extended life and pliability
• Resists electrochemical degradation (ECD), a common failure mode
• Temperature rating supports a wide range of operating conditions

Which systems and vehicles can this hose be used on?

The 18221L covers many GM-based heater and coolant routing needs and is one of many part numbers designed to reduce inventory while maximizing vehicle coverage. It can be used for coolant, water, and air lines where a molded branched hose is required.

• GM OE-style part for many GM applications and compatible replacements
• Approved for marine cooling use when application requires it
• Not suitable for fuel or oil transfer systems

What are the key dimensions and features to confirm fit?

The hose includes measured diameters and branch sizes to match original equipment routing. Confirm vehicle-specific fitment using dimensions and part cross-reference before installation.

• Diameter range and branch sizes: 1 in x 3/4 in x 5/8 in x 5/8 in
• Overall length approximately 19 3/32 in to align with factory routing
• Covered by ACDelco’s Professional line standards for fit, form, and function

Who is this for? The ACDelco Professional 18221L molded branched heater hose is aimed at technicians, independent repair shops, and DIY mechanics who need a reliable, OE-style replacement for GM and compatible vehicles. If you require a direct-fit coolant or heater hose that resists degradation, simplifies replacement in tight engine compartments, and matches GM routing, this hose is an appropriate choice. Always verify vehicle application and measurements before purchase to ensure proper fit and safe operation.