Hi, I'm getting a screeching sound from my belt after a alternator change. After I adjusted the tension screw on top of the pulley the noise stops. 15 / 20 after driving, noise again. When I check the adjustment screw it seems to have loosed and the noise is back. Changed the pulley first, didn't help. It seems the screw is coming loose while driving. Any idea?

 

May be the belt need replacement. Have checked.