Most likely it was the bearings in the water pump went bad. I had a mint 1968 BMW 2002 that without any warning the bearings in the water pump seized up knocking the fan blade out of alignment causing the fan to dig chucks out of the radiator.

Usually a water pump will leak first, but mine didn't. Just fix it and try not to cry too much!

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Old age and treachery will allways overcome youth and skill!

1993 S500
1984 380SL