If your vehicle is showing grinding or whining noise from the engine pulleys, here are the most likely causes and the parts you'll need to fix each one.
The bearings inside the idler or tensioner pulleys lose their grease and dry out over time, causing a continuous whining or grinding noise while the engine is running.
The internal bearings of the alternator spin at high speeds and frequently wear out, producing a high-pitched whine or grinding noise that rises in pitch with engine RPM.
A worn power steering pump or aerated fluid (due to low fluid levels) will cause a loud whining or groaning noise that typically gets much worse when turning the steering wheel.
The water pump bearing can fail, causing a grinding or rumbling noise. This is often a precursor to a coolant leak from the weep hole and can lead to severe engine overheating if the pump seizes.
The bearing inside the A/C compressor pulley can fail, causing a grinding noise. The noise often changes, worsens, or disappears entirely depending on whether the A/C is turned on or off.
If a manual tensioner is set too tight or an incorrectly sized belt is installed during recent maintenance, it puts excessive side-load on all pulley bearings, causing them to whine prematurely.