Alternator making whine noise

[Original 4th Gen V6]

I might try to give it a little shot of WD40 or something like that to see if it helps. Anyone else had this problem?

[Harbin1]

It sounds like the bearings are shot. You'll probably have to replace the alternator. I'm on my 5th one!

[bu-bye]

There are places that will do repairs for such thing at a cheap price. The bearings should not be hard to replace at all. You might want to see if you can get them from a repair shop and do it your self. Or just deal with the whine.

[rockotman]

If the alternator is making a whining noise, I would check the output to make sure that you are still charging the battery.

What can happen is that if a set of the diodes goes out, the 3 phase AC machine becomes an unbalanced 2 phase AC machine, and the unbalanced currents cause the armature and rotor to vibrate at a frequency dependent on the engine speed. This can sound like like a bearing whinning.

You can check to see if it is charging by turning on all electrical loads and measuring the voltage at the battery. If it won't stay at or above 13 volts while at an idle, it may be time to consider rebuilding or replacing the alternator.