Put on a new pulley bearing.
The roller bearing dates to at least 40 BC, and it was applied to pulley blocks sometime in the dim past of history. There is probably no way to know when someone first put a roller bearing into a pulley block.
It could be a bearing in an idler pulley.
A bearing used in a pulley is typically referred to as a "pulley bearing" or "sleeve bearing." These bearings facilitate smooth rotation and reduce friction between the pulley and its shaft. In some applications, ball bearings may also be used to enhance performance and durability.
In most cases you can purchase the bearing and pulley as an assembly from your local auto parts store.
If the tensioner cannot put a full 'load' on a new belt (as shown by the wear indicator markings on the side of the tensioner) - it's likely the tensioner requires replacing.NOTE: some sources recommend replacing it at 60,000A bad pulley (bearing) would be making whining/screaming noises.See "Related Questions" below for more
You can, for about 10% of the price of a new pulley, but you need a bearing press or hydraulic press to do it properly. A new metal pulley usually costs around $30, but the bearing can be obtained for $3 to $4.
Take off belt, remove bolt in center of pulley, replace with new pulley (comes with bearing). Reverse to install Take off belt, remove bolt in center of pulley, replace with new pulley (comes with bearing).
it is time to change bearing on that pulley
That pulley has a bearing on the inside of it that has gone bad. Replace the pulley with a new 1
If you're describing the idler pulley or the tensioner pulley, it's probably a bad bearing. Pulley bearing failure is common and relatively easy to repair. Remove tension from the serpentine belt then turn the pulley back and forth with your fingers. It should make no noticable noise and should turn smoothly. If you can hear any grinding noise or if the pulley feels like the bearing is grinding, replace it.
The drivebelt may be slipping, or a roller bearing dried out.
Probably either a loose belt or a bad bearing.