Stock Coolant Overflow Tank

The OEM Coolant Overflow Tank for the 2015+ WRX/STI does its job well enough. However, the cheap plastic material is ugly and will potentially crack over time.  This is especially true when driving hard and going through extreme heat cycles.  Also, it’s shape is clumsy and obtrusive when adding an aftermarket FMIC.

Luckily, COBB has you covered with an upgraded unit.  You might remember that we’ve already released a coolant overflow tank for the 15+ WRX and STI before.  This newer version is even better looking and doubles the capacity over its predecessor.

Upgraded Coolant Overflow Tank

The new and improved COBB Subaru Coolant Overflow Tank for the 2015 – 2021 WRX or STI solves the stock unit problems without any sacrifices. It is constructed of welded aluminum with the same 1L capacity of the OEM tank and is completed with internal and external anodizing. The COBB tank looks much better under the hood and provides a clean and simple mounting solution.  Its shape is also more conducive to fitting piping from an aftermarket Front Mount Intercooler.

A custom COBB Delrin, heat resistant, cap is included which adds to the overall clean look.  Plus, the kit comes with a silicone adapter hose and injection molded cap for the washer fluid reservoir.

This upgraded Subaru coolant overflow tank is affordable, easy to install, and improves both form and function. It’s a must-own part when installing an aftermarket front mount intercooler to make room for the charge pipe. But, it’s still a no-brainer anywhere else on the modification path to add style and convenience to the engine bay.

This Overflow Tank is now included in our Front Mount Intercooler Kits for the 2015-2020 WRX and STI.  Pricing for these and piping kits will include a slight increase as the new and improved coolant overflow tank is a little more expensive.  By comparison, the benefits of the new tank far outweigh the additional cost.  Interested in other mods?  Check out our list of Subaru performance parts.