Engine squealing

[tr_1127]

The engine on my 2004 ST has recently started squealing. The squealing increases with speed, so I thought that it might be the serpentine belt, but the grooves in the belt appear to be in good shape. I'm not so sure about the smooth side.

Is it normal for the smooth side of the belt to look like that?

Also, after the truck has been driven for a while, the squealing is nearly absent at low RPM.

To the best of my knowledge, every part that is driven by the belt has been there since the day it left the factory.

 

[ncranchero]

Spray a little belt dressing on the belt. If the noise goes away replace the belt, Goodyear Gatorback is highly recommended. If it doesn't go away, remove the belt and examine the idlers/tensioner.