Urgent help needed
I have C class 180 W203, recently i have noticed the car is making funny noise where the Gear box is located and took it to mechanic after 20 mins drive they said no faults were found ( i wasnot presented at the time of driving). However, this freaking noise still there and i aint sure what is it .
Actually when the car is stationary with engine on it doesnot make noise but you drive for 4 or 5 km then you can hear this annoying noise ( like bird singing or whistling) 
. Does anyone know what it could be ?Cheers guys




I have C class 180 W203, recently i have noticed the car is making funny noise where the Gear box is located and took it to mechanic after 20 mins drive they said no faults were found ( i wasnot presented at the time of driving). However, this freaking noise still there and i aint sure what is it .
Actually when the car is stationary with engine on it doesnot make noise but you drive for 4 or 5 km then you can hear this annoying noise ( like bird singing or whistling) 
. Does anyone know what it could be ?Cheers guys



@ Carsy , it s 6 speeds manual.