I have a Ford Mustang. Today I drove the car almost 150 KMs at normal speeds. When I Stopped the car, the radiator water drained out completely. What is the reason for that? What will be the cost for repair?
The reason is most likely because you have a leak in the system - this could be in various different places, for example:
Cost for repair will be dependent on what component the leak is in and where that component is.
Another possibility is that the radiator has overheated and the water has escaped as steam - which could happen through pump failure, blockage etc.
Did the water escape as steam or drain out onto the road?