Check the motor of your radiatorz fan..............may be possible the connection is inversed, resulting in movement of fan in opposite direction.
If this is not the problem.......and the gaskets and radiator is also f9.........u can swap the fan with a heavier one (motor and fan), i had same problem with my G-11 charade 2-3 years back.......after installing the fan and motor of margalla........the problem was solved
For Mehran..............i had the same problem.........got the radiator replaced aur jan chut gayi.......btw it was mehran 1992