Idler pulleys guide the belt and provide a 'routing point' where there are no prephrial components to be routed through. An idler pulley attached to a spring loaded arm is a tensioner pulley.
Idler pulleys can wear down over time, often ending up with the bearings making a soft grinding or squealing noise. When this happens it's time to get them replaced!
The serpentine belt must be removed to replace an idler pulley, however on most vehicles it will be a straightforward proceedure.
We stock and sell a wide variety of quality idler pulleys from these manufacturers: