Compatible: (2.0L/2.3L)

2013 – 2018 Ford Focus ST

2016 – 2018 Ford Focus RS

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

Add some reliability and engine bay styling to your Focus RS/ST with the Mishimoto RS/ST expansion tank. This tank features internal baffles to prevent coolant starvation from overflow ports on the engine. Also, during high-speed cornering, braking, and acceleration, the internal baffles reduce coolant sloshing. The engineers at Mishimoto have included a sight tube to allow for proper observation of hot and cold coolant levels, making engine maintenance much easier.

Eventually, youll have to consider the health of your plastic expansion tank. Plastic is prone to failure after years of constant temperature variations. The Mishimoto tank is constructed from durable, TIG-welded aluminum for optimal durability and longevity. It reuses the stock expansion tank cap and includes an overflow nipple on the fill neck for adding an additional coolant tank so your Focus RS stays NHRA legal. All areas of concern are covered with this upgrade.

Its worth noting the Focuss stock tank is an engine bay eye sore, whereas the Mishimoto tank comes in three different variants to help with aesthetic customization: black, wrinkle red, or Wrinkle Nitrous Blue. Each of these options works with both the 2013+ Focus ST and the new 20162018 Focus RS. For convenience, you can install your new coolant tank upgrade in under one hour as it was engineered with perfect fitment in mind. Like all our Focus RS parts, this expansion tank also includes the Mishimoto Lifetime Warranty.

• Direct fit for the 20162018 Ford Focus RS / 2013-2018 Ford Focus ST
• Sight tube allows for proper hot and cold coolant levels
• Internal baffle keeps coolant near overflow port during aggressive driving, preventing air entry into coolant system
• 100% aluminum, fully-welded construction for maximum durability during repeated temperature transitions
• Overflow nipple on fill neck allows for installation of additional NHRA-mandated overflow reservoir
• Fits with stock overflow tank cap
• Available in Wrinkle Nitrous Blue, wrinkle red, or black powder-coated finish
• Mishimoto Lifetime Warranty

PURCHASE INCLUDES

(1) Aluminum Expansion Tank w/ Sight Tube
(1) Overflow Hose
(2) Rubber Sleeves
Mishimoto Lifetime Warranty

TANK LOVE COOLANT EXPANSION TANK R&D, PART 1: DESIGN PLANS

Anyone with a car older than 15 years or so likely has a coolant expansion tank with the structural integrity of wet toilet paper. These tanks rarely get aesthetic love in the factory vehicle design. They are usually plastic, look weird and can start cracking given enough time. After 20 years, the expansion tank in my 1995 Nissan 240SX project car will literally begin crumbling around your finger if any sort of pressure is applied. We dont want that happening to your RS/ST a decade or two from now, so we decided to design a sweet looking expansion tank that will outlast the car and be a nice addition to your engine bay.The stock cap on the RS has a pressure limit of 21psiFactory expansion tank for the ST

There is a lot offocus(I havent made that pun in a while, give me a break) devoted strictly to improving how this EcoBoost hot-hatch platform performs since its introduction. Thisisimportant, our engineers have that as a clear goal in their minds. For our RS, weve releasedan oil cooleranda catch can, whilean awesome performance intake,acomplete intercooler setup, including pipesanda bad*** rear differential coolerare all on the way (see ourentire product line for the STas well). Trust me, we will make our RS fly like a bat-out-of-hell once were done with it, but how many products out there add a little bling to this platform? Certain parts may not make you faster, but they can always look better.

Mishimoto cares about making you look good, so this project has moved fast. We have already begun making a 3D model of our tank design and had it 3D printed to test the fitment on our RS (fun fact, itwill fit both the RS and any 2013+ ST!). To save time, we printed this entire assembly in pieces. You will notice a line in the middle of the tank, this is where the halves were epoxied together. The fill neck was also printed by itself, and had to be attached to the body of the tank separately. Remember, this isnt a functional prototype, our engineers just wanted to be sure the design fit. See below.

The underside of the tank showing the feed and return port linesYou can see the horizontal line splitting the two

Another cool thing we are doing with this tank is adding a sight tube. In past expansion tank projects, it hasnt always been a feature that we could add due to how the design fit the vehicle application. We incorporated a sight tube here so you can tell how much fluid is in the tank without much trouble. There is also internal baffling that will prevent slosh.

The sight tube was printed along with that half of the tank

Now that we know the prototype fits, its time to get a real, functional prototype into our facility. The good news is that we have a few on the way! Ill leave you with what this prototype looks like on our shop RS. Just imagine whatever finish you think would work for your ride and youll pick up on the complimentary design we are going for!

TANK LOVE EXPANSION TANK R&D, PART 2: FINAL REVEAL

I told you this project was going to move fast. In the last update, we laid down our design plans for how we will give this RS coolant expansion tank some sprucing up. Not only did we make the tank more pleasing to look at, we also increased the capacity and added a neat sight tube so you can check your levels with ease. You guys have been asking for it, so lets get up close and personal.The stock unit pales in comparison to the size of the Mishimoto tank.

One of the first things youll notice with this tank is the capacity increase over the stock unit. We are making this tank to fit both the Focus RS and ST, but that doesnt mean we have to stay within the size parameters of the stock unit. The stock expansion tank holds a maximum of 1.56 liters of fluid. Our design more than doubles that, with a maximum fluid capacity of 3.58 liters. With the increase in capacity comes an increased chance of fluid sloshing inside the tank during hard driving. To combat the extra fluids movement, we designed some internal baffling that should keep sloshing at bay.

See the sight tube on the left of the tank?

Another interesting feature we include on this expansion tank is a sight tube attached to the side of the tank. Due to design constraints. its not always possible to include something like this in an expansion tank, but it happened to work out nicely in this case. In order to monitor your tank levels, all you need to do is look at the sight tube easy! So, what does this tank look like installed?

The finish matches with the engine cover

The stock unit on the ST and RS stands out like a sore thumb. Our design, on the other hand, is quite pleasing to look at and almost looks like an OEM part. Its an improvement from the plastic stock part in two ways: 1) its constructed with aluminum; and 2) it doesnt look like a makeshift experiment with a milk carton. One thing I really like about this finish is how well it matches with the engine bay components. There is a lot of black plastic in the engine bay, and this tank ties everything together. We are car enthusiasts, too, so know you want to feel proud whenever you pop the hood and see a matching engine bay.