Compatible: (2.3L/3.7L/5.0L)

2015 – 2023 Ford Mustang EcoBoost

2015 – 2017 Ford Mustang V6

2015 – 2023 Ford Mustang GT

After a few hot and cold cycles, Mishimoto recommends checking the sight glass on the side of the expansion tank to confirm proper coolant level.

Add some additional reliability and engine bay styling with the Mishimoto V6, V8, and EcoBoost Mustang expansion tank. The Mishimoto Mustang expansion tank has internal baffles to prevent coolant starvation from overflow ports to engine. Also, during high speed cornering, braking, and acceleration, the internal baffled reduce coolant sloshing. The engineers at Mishimoto have also included a sight glass to allow for proper hot and cold coolant levels. The stock coolant Mustang expansion tanks is major eye sore in the engine bay, so the Mishimoto tank is offered in polished or anodized black to keep your Mustang looking great. As an added feature, you can install your tank in under one hour! This Mustang expansion tank was designed to work with the stock expansion tank cap and includes an overflow nipple on the fill neck for adding an additional coolant tank so your Mustang is NHRA legal. Plastic expansion tanks are prone to failure after years of constant temperature variations, so the Mishimoto tank is constructed from durable, TIG-welded aluminum for optimal durability and longevity. The Mishimoto V6, V8, and EcoBoost Mustang expansion tank is engineered for perfect fitment in 2015 Mustang, and as with all our 2015 Mustang parts, this expansion tank includes the Mishimoto Lifetime Warranty.

• Direct fit for the 2015+ Ford Mustang EcoBoost, V6, and V8
• Internal baffles keep coolant near overflow port during aggressive driving, preventing air entry into coolant system
• Sight tube allows for proper hot and cold coolant levels
• Installs in under 1 hour
• Overflow nipple on fill neck allows for installation of additional NHRA-mandated overflow reservoir
• 100% aluminum, fully-welded construction for maximum durability during repeated temperature transitions
• Fits with stock overflow tank cap
• Available in polished or black powder coat
• Mishimoto Lifetime Warranty

PRODUCT SPECS

PURCHASE INCLUDES

(1) Aluminum Expansion Tank w/ Sight Glass
(1) Overflow Hose
(3) Worm-Gear Clamps
Mounting Hardware
Mishimoto Lifetime Warranty

2015 MUSTANG EXPANSION TANK PROJECT, PART 1: STOCK TANK AND 3D MODELING

Its hard to match that feeling you get when purchasing a new car, especially the new S-550 Mustang. Picking up your friends for joy rides, melting the tires down the full length of your neighborhood, pulling into the driveway, popping the hood in complete ecstasy wait what is that? Is that the coolant expansion tank? Why is it so terrible looking?

This is pretty similar to what happened the day our shop 2015 EB arrived. The engine bay on both the 2.3L and 5.0L vehicles is quite nice, well organized, and clean. Unfortunately, right up front in plain sight sits quite an eyesore in the form of your coolant expansion tank. To improve aesthetics, we decided to tackle R&D to bring you guys a more appealing alternative to the stock tank.

Stock Expansion Tank Exterior

Before jumping into a design of our own, we needed to capture the dimensions and features of the stock unit to ensure that we include these in our component.

Stock Mustang expansion tankStock Mustang expansion tank

This tank features three coolant ports; two are on the top and one is on the base of the tank.

Stock Mustang expansion tank portsStock Mustang expansion tank ports

Despite the primary portion of this tank being constructed from plastic, these ports feature a metal internal sleeve to prevent failure. If youve ever removed hoses from an old radiator or expansion tank, you will understand how brittle this plastic can become.

Stock Mustang expansion tank ports

The last remaining external features to consider are the cap threads and fill neck, which are shown below.

Stock Mustang expansion tank cap

Stock Expansion Tank Internal Construction

Stock Mustang expansion tank split

Although it is only slightly noticeable from the shape of the exterior, the internal portion of this expansion tank features a ton of baffling. To get a better look, we sliced the expansion tank in half and had a look inside.

Stock Mustang expansion tank splitStock Mustang expansion tank split

Each half is shown individually below.

Stock Mustang expansion tank splitStock Mustang expansion tank split

Whats with all the chambers? The chambers in the tank are in place to prevent any sloshing of coolant during hard cornering. One of the ports requires submersion in coolant to function properly, and if coolant were to end up below the port location, air would enter the system. As you may know, air within the cooling system can cause serious issues. An air pocket will restrict or block coolant flow which can cause massive temperature fluctuations and overheating. If an air pocket exists, it must be purged from the system to avoid continual overheating concerns. If the port in question were to become exposed to air during hard cornering, the possibility of air pockets entering your coolant system is quite high. This is not something you want to occur at a weekend autocross or track day.

These baffles are just as important as every other feature on this expansion tank.

Baffle Testing

We wanted to see firsthand what impact this baffling would have on coolant movement. We set up a quick testing rig, shown below, to perform our science experiment. We wanted to evaluate the performance of the baffles during simulated driving conditions to determine the need for these in our expansion tank design. We put together this testing rig to show how coolant would react within the baffled tank as well as an empty container without baffling.

Expansion tank baffle testingExpansion tank baffle testing

We then strapped on our new Go-Pro camera and produced conditions similar to a ride on rough terrain and with aggressive cornering (such as at an autocross). Check out the video!

As you see from these photos/videos, the OE expansion tank isnt just a plastic jug designed to hold coolant, it is a highly engineered piece which needs a well thought out solution to not only improve under hood aesthetics, but also keep your factory cooling system functioning properly.

With this testing in the books, and in