On my 2001 Blazer, Alternator has since I have owned it (one year) made a slight whine, that becomes inaudable at high speeds and seems to go once driven for a decent time. I put a screwdriver against the top left 'wing' section of it which is where I can hear it to confirm. My reading on the dash is a consistent at 12 oclock, the battery charge on key turning reads at 10.30, readout on battery itself shows a green dot. It starts fine, even when driven short distances continuously.
Lost all my charge once by leaving key in ignition overnight, normal I assume.
My question is, should I worry about the whine, (sounds like a turbo type noise), are my dash readings normal.
thanks

 

You have bad bearing. I paid $1.5 for rear alternator bearing recently. they are small and cheap. Front one would be about $5.
Remove bad bearing, measure it in mm and call local bearing store.
I use stethoscope ($3 from Harbor Freight) to diagnose alternators, compressors, water pumps, belt pulleys etc

 

I thought bearing noise was more of a grinding sound??. Is the blazer alternator servicable. Im in the uk guess I could order bearings from the us if that what it is. Just checked youtube for bearing noise and its not that Im sure, more like a whistling sound, but definately from the Alternator