Koyorad Aluminum Radiator Filler Neck

Koyorad Aluminum Radiator Filler Neck - Toyota GR86 / Subaru BRZ (2022+)

Billet Aluminum Durability & Integrated Sensor Port

Eliminate the weak link in your cooling system with the Koyorad Aluminum Filler Neck. The factory plastic filler neck is notorious for developing micro-cracks and suffering from steam erosion over time, which can lead to sudden coolant loss and engine overheating. This Koyorad unit is CNC-machined from high-grade billet aluminum and finished with a mirror-polish. Not only does it provide superior structural integrity, but it also features an integrated 1/8 PT sensor port, making it the perfect mounting point for an aftermarket water temperature gauge

What’s Included in the Box:

- Koyorad Billet Aluminum Filler Neck: (1) TIG-welded, mirror-polished assembly.

- 1/8 PT Port Plug: Pre-installed for those not running an auxiliary temperature sensor.

- Direct-Fit Mounting Bracket: Integrated for a 5-minute bolt-on installation.

The Koyorad Advantage

- Eliminates Plastic Failure: Replaces the OEM plastic neck that is prone to "brittling" and cracking due to repeated heat cycles.

- Integrated 1/8 PT Sensor Port: A built-in port allows for the seamless installation of water temperature sensors from most major Japanese gauge manufacturers (Defi, GReddy, HKS, etc.).

- 100 Percent TIG-Welded: Hand-welded at Koyorad’s private ISO 9001 certified factory to ensure a leak-proof, high-pressure seal.

- Mirror-Polished Finish: Adds a premium, high-end look to your engine bay that complements other aluminum and carbon fiber upgrades.

- OEM Compatibility: Designed as a 100 percent direct replacement, this unit is fully compatible with your factory coolant hoses and spring clamps.

Product Specifications

- Part Number: FN3037

- Material: Billet Aluminum

- Sensor Port: 1/8 PT (with optional plug)

- Finish: Mirror Polished

- Installation Type: Direct Bolt-on (Approx. 5-minute install)

Vehicle Compatibility

- Toyota GR86 (2022, 2023, 2024, 2025, 2026+)

- Subaru BRZ (2022, 2023, 2024, 2025, 2026+)

CRITICAL INSTALLATION NOTE: This filler neck is designed to accept a more robust, high-pressure "deep plunger" style radiator cap. The factory (OEM) radiator cap will NOT fit this unit. You must use a Koyorad SK-C13 radiator cap or an equivalent deep-plunger type cap for a proper seal. Failure to use the correct cap will result in cooling system leaks.