Ghuncha....man...i do trust you but you tell me, is it sensible to pour water over your car's radiator. I used to drive a suzuki fx back in the late 90s when i was in Karachi and never had this problem.
My suggestion to alto owners with this problem, look into upgrading your radiator. It seems that Suzuki is putting cheap quality radiators in altos/mehrans which is not capable of dicipating heat.
You guys are diving the mehrans so you know best. Can u put khyber's radiator in the mehran???