Description Reviews Do you have a leaking coolant tank? The coolant expansion tanks on the very early MINI Cooper S were very common to leak at the seam. Maybe you're looking to dress up your engine bay? This Forge Alloy Header Tank will replace the plastic one, giving you the strength of aluminum to hold up to cooling system pressure. It bolts into the stock mounting bracket with no modification needed. The Forge unit is designed to reuse your stock coolant tank cap; but if you're seeing a problem there, we have you covered. For a few extra bucks get the cap to complete the package. Looking for something a bit cheaper? Look at the stock replacement.