Bad alternator bearings?

sagebel · Apr 10, 2015

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 · Apr 11, 2015

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 · Apr 11, 2015

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 · Apr 14, 2015

Dab of dielectric grease on the top of the belt.

sagebel · Apr 14, 2015

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 · Apr 14, 2015

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

ToMang07 · Apr 14, 2015

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 · Apr 19, 2015

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 · Apr 19, 2015

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.