Have a Ford Mondeo X-Pack Estate, 2015 plate. Started overheating today as soon as I go over 40m/h. Engin coolant levels appeared to be in order. Stopped vehicle, kept motor running, waited for motor to cool down. Could hear fan running, but also heard weird clicking sounds for a few seconds. While motor running continued to unscrew cap on reservoir and all the flued just flushed away to its lowest level. Filled reservoir back up with engin coolant to fill line. Continued my journey, but vehicle kept overheating, but not as much as prior to continuation of my journey. Any ideas from somebody that might have had a similar experience or somebody that has the expertise. Much appreciated in advance.