Well, i have this nasty whirring noise coming from the PS location. when i use the stethoscope it seems to originate from the alternator, like a bad bearing noise. I also swapped PS pumps with a spare I have just to be sure, but noise is still there, and when u scope the pump it is silent,.

Anyway I also noticed this morning my air solenoids werent acting properly and the cd deck kept cutting in and out when messing with the airride..seems like a voltage issue.
Yep, car running im seeing 11.5 volts, revving it up to 4000 rpm the voltage slowly rises up to a max of 12. This seems to confirm the bad alternator.

Anything else it can be? Clearly not a fusible link as the voltage does in fact rise, although very little.
I wonder if the brushes are toast on it? With twin compressors and a large stereo i know I am loading it way more than a stock unit would see.

 

It's hard to tell if it's just brushes or brushes + bearings based on what you said, but it does sound like a failing alt.

 

it could be more than just the brushes. best to just replace the alternator completely with a rebuilt unit or a higher output one for your extra components.

are you running a capacitor for the stereo? what kind of compressors are you running? viair comps are known to draw lots of current depending on model.

 

Tein viair 400s and no cap! I have one sitting still nevet put it in. With no cap and the subs hitting i assume itnis putting a "shock" loading onto the alternator. Picking up a used one yomortow for 60$, dont trust the part store lifetime warranty ones for $200, and no time to order a higher output unit from my guy, need the car ready for woodward dream cruise this sat!

 

took it to oreileys, put it on the mahcien and it started screeching. Yup bearing is toast and failed all tests. Picked up a used one for 40 bucks...hope it gets the job done till i can get a built one.