Bad alternator bearings?

[sagebel]

I'm getting a squealing sound from what sounds like near the alternator. I didn't have time to really look at it today but plan on troubleshooting tomorrow. It's making 14.1 volts. What is the best way to isolate the squealing noise under the hood?

 

[mandkole]

Have you made sure its not the belt? Shoot a very quick shot of brake cleaner on the belt ribs as it enters the pulley. The brake clean evaporates fast and for very brief use, it wont hurt the belt. Id shoot it on a number of surfaces in the accy drive around the alternator.

 

[sagebel]

Thanks, I'll hopefully get to it tomorrow. I listened to it this morning using a stethoscope and couldn't pinpoint it. The sound seems to stay the same as engine rpm changes.

 

[MorganY]

Dab of dielectric grease on the top of the belt.

 

[sagebel]

I haven't had a chance to really look at it due to work. There is no noise when the truck is warmed up, just a start-up. Changing the belt (and anything else on the front of the engine) looks like a PITA.

 

[MorganY]

It's not bad to replace. A dab of dielectric will keep the noise out of it.

 

[ToMang07]

It's probably the alternator. Both my brother's F150s have loud ones...obnoxious when it's really cold out. Cheap, Chinese made bearings.

 

[sagebel]

So I tried everything mentioned and none of it eliminated the noise but after making a 684 mile round trip yesterday the noise was not present this morning.

 

[08RED4x4]

I just had the alt bearings replaced on my f150, at idle they sounded like a had a supercharger with all the whine they were making. Just to give an idea of how those bad bearings sounded.