The cooper has a flip cap the cooper s has a screw cap which is a pressure cap and its crap , if only there were 4 components that fail : the pas fan on early cars if jammed would blow a fuse , through a mastery of design the same fuse runs the cooling fan for the rad .
The rads split at the plastic join on the side , this leak is hard to spot , the fans control temp can go random from the control unit , the header tanks split at the seam and loss of pressure and coolant , the water pump on the back of the charger can have a drive failure , loss of charger belt = overheat , even when all is working the cylinder cooling is not even across the engine
SO other than the pump ,the rad ,the stat , the fans, the header tank , the tank cap , the gauge, and the control unit - it's a great system a design marvel .....