blog post 13

Say No to Plastic – Coolant Expansion Tank R&D, Part 1: Initial Design

Time to dive into yet another Fiesta ST project! This little Fiesta is getting the royal treatment at Mishimoto; over the last few months it has been fitted for numerous upgrades. If you are in the mood for a recap, you can check out some of the other Fiesta posts here on the Mishimoto blog. For now we’ll dive right into our development of Mishimoto’s expansion tank for the Fiesta ST.

Stock Expansion Tank

Here at Mishimoto we feel a certain type of way about plastic. It is not that we have a vendetta against plastic, but we see an area where we can improve upon some of the stock Fiesta ST parts. Plastic expansion tanks in general (or any plastic parts) are more prone to failure than an aluminum part would be. Plastic becomes brittle with age, exposure to elements, and the repeated heat cycles in the engine bay. Replacing the plastic tank with an aluminum one not only looks better, but it also would be less prone to bursting or cracking especially as the Fiesta ages. Check out a couple shots of the stock Fiesta ST expansion tank.

Stock Fiesta expansion tank in engine bay
Stock Fiesta expansion tank in engine bay

The stock expansion tank is your run of the mill plastic expansion tank. There are no impressive additions from the factory that we would be required to recreate (as seen on some of our other expansion tank projects). Ford did, however, have an interesting design for the inside of the tank. Lets take a closer look at the inside of the stock Fiesta ST expansion tank.

Stock Fiesta expansion tank
Stock Fiesta expansion tank
Stock Fiesta expansion tank
Stock Fiesta expansion tank
Internals of stock Fiesta expansion tank
Internals of stock Fiesta expansion tank
Internals of stock Fiesta expansion tank
Internals of stock Fiesta expansion tank
Internals of stock Fiesta expansion tank
Internals of stock Fiesta expansion tank
Internals of stock Fiesta expansion tank
Internals of stock Fiesta expansion tank

It’s not all bad! The inside design is intricate, featuring many compartments and grooves to prevent sloshing. We will certainly incorporate this style into our design because we want improved function in addition to form.

3D-Printed Version

After a thorough look inside and out, we took some measurements of the stock unit so we could create a prototype version with our 3D printer. The prototype fit nicely into the space for the stock expansion tank and there were no clearance issues with other Fiesta ST parts in the engine bay. Check out some shots of the 3D-printed version below!

3D printed Fiesta expansion tank in relation to other Fiesta ST parts
3D printed expansion tank in relation to other Fiesta ST parts
3D printed Fiesta expansion tank installed on the ST
3D printed Fiesta expansion tank installed on the ST
3D printed Fiesta expansion tank installed on the ST
3D printed Fiesta expansion tank installed on the ST
3D printed Fiesta expansion tank installed on the ST
3D printed Fiesta expansion tank installed on the ST
3D printed Fiesta expansion tank installed on the ST
3D printed Fiesta expansion tank installed on the ST

Coming Up!

Now that we have confirmed fitment with our 3D-printed expansion tank for the Fiesta ST, we can move on to create an aluminum version for additional testing. Stay tuned for more on this and other Fiesta ST parts in our next post!
Thanks for Reading!
-Sara

Leave a Reply

Your email address will not be published. Required fields are marked *