Description Reviews MINI Cooper S Turbo Coolant Return Lines run from the turbo to the bottom of the thermostat as well as the expansion tank. We have seen this line leak at the o-ring fitting at the bottom of the expansion tank from years of oil services. We have also seen the line rust badly at the turbo from years of hot and cold combined with water spray coming through the radiator when it rains. No matter why you need to replace it, it is a quality MINI part and comes with all new clamps. Fits both N14 and N18 engines and is the newest, up to date part.