Uh oh....
 

So, replaced the belts and all three pulleys for both belts last weekend.

Today, literally 30 minutes ago, started getting a horrible whining sound from the engine compartment, whether sitting or driving.

Thought it could be one of three things:

1. One of the three pulleys is defective
2. Electric engine fan going bad
3. Water pump in first stages of death

Pulled it into the garage and popped the hood with the engine running. First thing I noticed is that the wine is coming from the passenger side of the engine. Not cool. Thinking the water pump.

Anyone else had loud whining from a dying water pump?

I had the exact same thing happen to mine. Turns out it was the AC pulley bearing. There’s a write up on here somewhere for the replacement. It’s not hard (and dirt cheap) but requires a press.

Edit: the writeup is on youtube actually:

https://www.youtube.com/watch?v=5qd0e-vVxQA

You will need Santech MT2031 bearing purchased at Autozone for $15. I did all of the work from above and used the recommended snap ring pliers in the video.

This is all assuming you have a 4.8.

No, I have a 3.0 N52N

Oddly, when I turned off the AC thinking it was that, it still whined. I wonder if the 4.8 and the 3.0 use the same AC unit. Also, I have Adaptive Drive, so that might change things.

It will still whine with the AC on or off. The bearing is always spinning on BMW compressors. There is no clutch.

Good point. Going to look at that write up. Thanks for the tip.

I did just run the car through the cooling system bleed procedure. Only heard the little very quiet whine from the pump as it cycled on and off to circulate the coolant. Nothing loud and noisy. Of course, when I started the car, I also didn't hear the freakish whine I heard earlier. Since the bearing seems to be pretty cheap, I might just replace it anyway.

Just looked at the CarFax and saw no evidence of the original water pump ever being replaced by G&C Tire and Auto by the previous owner in Chantilly VA (Avoid them like the plague, they tossed crap parts at this X5, an indonesian radiator, cheap 3rd rate belts, and a "Carquest" oil filter). So, obviously, I'm terrified of the day that pump goes.

Wish me luck.

Check out this write up. It’s for the N52: https://xoutpost.com/bmw-sav-forums/...-30-3-0si.html

Sounds very similar to the 4.8 procedure.

You are the man!! I was looking for exactly that! (Search tool doesn't like me)

Good luck!