If anyone can help me out figuring what the cause of this noise is, that'd be awesome! it's a 1992 940 Turbo
Here's a vid of the squeal;

thanks!!!!

 

Sounds typical of slipping belts. The WP and AC belt may be glazed and should be replaced. They may look good on the top but the underside is slipping.

 

For a minute I thought it was the Cam belt tensioner but the closer you got to the Alternator the louder it got, so my guess would be a bad bearings on the alternator. Remove the belt to the alternator and turn the pulley by hand and see if it feels smooth as glass, if it's not, that's what is making the squealing noise .

 

Wakdaddy, that sounds like metallic interference and slipping belts ; here's something else to check on. The alternator adjustment bolts on these cars are quite long and can rub against the back of the spinning water pump pulley. Look for a shiny rub mark on the very back of the pulley, and a rubbed area on the threads of the alternator adjustment bolt or the nut/follower that rides on the screw to give it the adjustment. Get a bright light and an inspection mirror ( or inspection camera) and look back there.
Typically, the noise is worse at startup; gets better or goes away completely when the car is warm. To fix-1. cut off the offending bolt just shy of the pulley if the alternator belts are long or stretched out 2. remove the waterpump pulley and place 4 equal length washers on the studs behind the pulley and then reinstall. This will push the WP pulley out the distance of the washers that will push it away from the screw/nut.
If it is the nut/follower, try loosening or tightening the belts just enough to give clearance.

 

I think you need to take another look at the video again, the water pump pulley on the other side of the engine, just say'n..

 

Just take 1 belt off at a time and when the noise stops check each part for bearing or belt noise. Not rocket science here.

 

Sounds like a bearing... Eliminate the belts by running a soap bar on each while running the car. This will quiet them for a while. Take them off one by one then to see what bearing is involved.

 

Sounds like a crispy water pump, but that looks like a new water pump.

 

I agree with "lev". Sounds like Alternator bearings. A belt whine is higher pitched.. In my humble opinion.