1995 f150, 2wd, straight 6, 5 speed manual transmission
Whirring, grinding, rubbing sound.
It just started about a month ago.
Feel it in the gas pedal. A vibration.
Intermittent, occasional. Sometimes won't hear it for a day or 2.
If I hear it I'm probably going 25-35 mph.
Heard it once for a few seconds after going over a bump
Heard it once for a few seconds while taking a left turn
Heard it once immediately upon starting the truck, while stationary. Lasted about 5 seconds. Went away when I tapped the gas pedal a bit.
Seems to be coming from the engine compartment.
When it happens the speed of the truck seems to be affected. It slows down a little, like the brakes are being pushed slightly. Might be my imagination.

The frequency of the sound is constant. It does not change with truck speed.
Disregard that. I have not encountered the sound at a wide range of speeds. It DID sound the same when it happened upon startup as it did at 30 mph tho.

A belt going bad?
A bearing going bad?

UPDATE

Talked to a knowledgeable fellow who suggests that it's either a bad bearing in the AC compressor or the distributor shaft/gear thing ain't getting enough oil splashed up into it (thus requiring a degunking).

Test for AC bearing is to turn off the AC of course.
I might crack open the distributor.
Will post update later.

6/14

Left the AC off for the past week. The sound is gone. So there ya go.

 

I just had to replace my AC clutch, had an alternator do that too.

 

Check the U-joints.