The radiator is non-standard and not effective enough for the engine. The LVG's display is always limited by the length of time to coolant overheat and today it was HOT.
Money was made available to manufacture a new radiator a few years ago, but as the RAF Museum now want the aircraft back - it goes at the end of this season - and given the limited flying time then available, it was judged not to be financially viable to continue with the project. The overheat problem is managed by the pilots by limiting the flight time.
A