alternator bearing is bad

 

the alt. pully didnt have any play in it when i checked it without the belt. Since the squealing quiets when i shoot the belt with oil wouldnt that eliminate the bearings?

 

does not have to have play. could be a bad or bound bearing, when you checked the bearings, were any of them "gritty" or feel at all like an indexing volume knob on an old radio?
do all of the pulleys spin true, check with the engine running, there should be very little variance, also check to ensure everything is lining up properly, if a bracket is missing a washer it could be scrubbing on the side of the belt causing your squeak.

 

Sounds like a belt alignment to me.  Has the power steering pump been changed?  Is the pulley lined up properly?

 

how's your fan clutch?

 

with serpentine's its either the Alt or an alignment problem 

 

If everything is ok and it's just the belt, put a little Comet or Ajax cleanser on it....watch your eyes when you start the truck till it blows off...

 

I do not if this helps, but this it how it got solved in mine:

I had that same squeaking sound at start, got worse when driving, then stopped, then goes again, then stooped, and so on... and did not stop no matter what. I bought 5 different belts, and nothing... then I bought 2 new sets of pulleys. Nothing... so i decided to let it there... A couple of days later, I sent the truck to the electrical shop, and when I got it back, the squeaking was gone. It turned out that due to a non-working VR, alt was working in an erratic manner, thus making the pulley worked sometimes less than necessary, sometimes harder than necessary...

As I said, I do not know if this could help you, but you can always try...

 

Now here is what has happended at the dealerships I worked at with this kind of squeek noise. And why I know why the noise goes away when using the WD.  First by spraying the WD the belt is now no good, BUT dont chuck it.  ( The WD just makes the belt slippery enough so it wont "chatter"- squeek  on the pulleys
With saftey glasses on,
get under van with hood open, very bright shop light, start up engine and watch belt, is it "floating" back and forth on the idler or any pullyes? if so you will need to check your ps and alt pulleys. and make sure they are in align, after time those pulleys have a tendensy to "walk" on the shafts and come out of align. When you replace either part, when pressing the pulleys back on there is a shim tool that sets the proper depth of the pulleys on the shafts, and with age you will need to do this on the pulleys.    When done, clean clean clean all pullys and idler, and install a new belt. And use a factory belt, never never use the goodyear gator back belt, gates work ok, but have sometimes not worked well if they have been sitting on the self for a long time
Good Luck

 

Thanks for all the help. I google about belt dressings and it seems that it is very common for it to cause more harm than good. My next step will be to remove the belt and clean all the pulleys and then i will check there alignment. I did notice that the alternator had been replaced sometime within the past year so ill recheck its mounting