Koyo FN2316 Billet Aluminum Radiator Filler Neck for 2008-2015 EVO X

Vehicle Fitment

• 2008-2015 Mitsubishi Lancer Evolution X (Evo X) - all trims
• 2009-2015 Mitsubishi Lancer Ralliart (standard sedan / wagon trims) - models using stock radiator neck and coolant system

Features

• Billet-machined aluminum construction - stronger and more durable than OEM plastic filler neck
• Polished / mirror-finish for corrosion resistance and enhanced engine-bay appearance
• Retains factory coolant cap and uses original hoses / clamps - direct bolt-on replacement
• Includes 1/8" NPT (PT) sensor port (with plug) - for optional coolant-temperature or level sensor installation
• Better thermal resistance vs plastic - less prone to cracking or warping under engine bay heat
• Resists coolant-acid corrosion and long-term wear / fatigue from coolant pressure cycles
• Improved sealing reliability compared to OE plastic neck - reduces risk of leaks over time
• Lightweight construction - minimal change to vehicle weight distribution

Specifications

• Part number: FN2316 (Koyo) - billet aluminum filler neck for Evo X / Lancer Ralliart coolant system
• Material: High-grade billet aluminum
• Finish: Polished / mirror finish (raw-metal / clear-coat depending on supplier packaging)
• Mounting: Direct-fit - uses original OEM radiator cap, hoses, and clamps from stock plastic filler neck
• Sensor port: 1/8" NPT (PT) - plug supplied (if seller's spec) for optional sensor use
• Packaging: Single aluminum filler neck unit (1x) as supplied by manufacturer / aftermarket distributor

Included Components

• 1x Billet aluminum radiator filler neck (FN2316)
• 1x Plug for 1/8" PT sensor port (if provided by manufacturer / vendor)

Product Description

The Koyo FN2316 billet-aluminum radiator filler neck is a robust, high-quality replacement for the stock plastic coolant-neck assembly used on 2008-2015 Mitsubishi Lancer Evo X and 2009-2015 Lancer Ralliart. By upgrading to aluminum, you gain superior durability, greater heat resistance, and a more premium under-hood finish - ideal for performance-oriented builds, track cars, or everyday reliability upgrades. The part installs directly using factory coolant cap, hoses, and clamps, making replacement simple and bolt-on.

A notable advantage is the integrated 1/8" PT sensor port, which - when used with an appropriate coolant-temperature or level sensor - enables coolant-system monitoring without additional modification. The billet aluminum body resists cracking, warping, and chemical degradation that can afflict plastic necks under high temperature or stress, reducing the chance of coolant leaks over time.

This filler neck is a practical, long-lasting upgrade for any Evo X or Ralliart owner seeking improved reliability and a cleaner, more performance-oriented engine bay. Before purchasing, ensure your vehicle is within the 2008-2015 (Evo X) or 2009-2015 (Ralliart) model years and uses the standard radiator layout - as FN2316 is designed to match stock coolant system dimensions and mounting points.