KOYO Aluminum Radiator Filler Neck

2022–2026 Toyota GR86 / 2022–2026 Subaru BRZ

FN3037

Overview:

The KOYO Aluminum Radiator Filler Neck is a premium upgrade designed specifically for the 2022 to 2026 Toyota GR86 and Subaru BRZ models. This high-quality auxiliary filler neck replaces the factory plastic component with a durable, all-aluminum construction that enhances both reliability and engine bay aesthetics. Ideal for enthusiasts seeking a robust and stylish solution, this filler neck withstands heat and wear better than the OEM part, ensuring long-lasting performance.

Whether you drive your BRZ or GR86 daily or enjoy spirited driving, this filler neck offers a simple yet effective improvement to your cooling system’s durability and appearance.

Key Features:

Designed with precision and quality in mind, the KOYO Aluminum Radiator Filler Neck offers several notable benefits:

• Constructed from high-grade aluminum for superior strength and heat resistance compared to factory plastic.
• 100% TIG-welded construction ensures a strong, leak-proof seal and exceptional durability.
• Finished with a mirror polish that adds a clean, professional look under the hood.
• True drop-in replacement requiring no modifications to your vehicle’s existing cooling system.
• Compatible with Koyorad SK-C13 type pressure caps or deep plunger equivalent caps for proper sealing.
• Lightweight design that maintains OEM fitment and function without adding unnecessary bulk.
• Resistant to cracking and deformation caused by heat cycling and vibration over time.

Construction & Design:

The filler neck is expertly crafted from premium aluminum, chosen for its excellent thermal conductivity and resistance to corrosion. The 100% TIG-welded joints provide a seamless, robust assembly that stands up to the demanding conditions of the engine bay. The mirror-polished finish not only enhances visual appeal but also helps resist oxidation and surface wear. This design approach ensures that the filler neck maintains its integrity and appearance throughout its service life.

KOYO’s attention to detail in engineering this component guarantees a precise fitment that aligns perfectly with the radiator and cap, preserving the factory cooling system’s performance and reliability.

Installation & Fitment:

This aluminum filler neck is engineered as a direct replacement for the factory plastic neck on 2022–2026 Toyota GR86 and Subaru BRZ models. Installation is straightforward and can be completed in under five minutes without any cutting, drilling, or special tuning required.

• Uses existing mounting points and radiator connections for a secure fit.
• No modifications to hoses or surrounding components necessary.
• Note: This filler neck is not compatible with the OEM pressure cap; it requires the Koyorad SK-C13 type cap or a deep plunger equivalent for proper sealing.

What's Included:

• One KOYO Aluminum Radiator Auxiliary Filler Neck
• Installation instructions

Ideal For:

This product is perfect for Toyota GR86 and Subaru BRZ owners who want to upgrade their cooling system components for improved durability and style. It suits daily drivers, weekend enthusiasts, and track-day participants who demand reliable performance and a clean engine bay appearance.

Koyorad (Koyo) builds cooling system upgrades, including application-specific aluminum performance radiators designed to improve heat rejection for hard-driven street and track vehicles. It’s a trusted choice for boosted and high-revving builds where controlling coolant temps is critical to consistent power and reliability.