2007 Tahoe high pitched sound (depends on engine rotation)
 

Hey there,
first, sorry for bad english, im from Germany ;-)

I'm new here and i just bought an 2007 Tahoe with 220.00 km (about 137.000 mls). The Vehicle is in good condition and got all of the maintenance service requested in manual. Of course, 150.000 mls service is NOT DONE.

So, i drove about 240 highway miles and some more in city, without noises or something. Car sounds like purr cats ;-)
However, since 5-10 mls, the car makes high pitched noises from engine. In P or N you can't hear it, same in IDLE. It begins at about 1000 rounds and becomes faster with more rounds, or slower on less rounds. If engine goes back to IDLE (about 500 rounds on working temp.), noise stop or is to quiet to hear. First i thought its the top left pulley of main belt (found in some similar topics here), but it isn't. It sounds more central, maybe the big Pulley above the engine axis (see attached picture). But i don't even know, for what this pulley is. I have an repair manual, but can't find informations about it (its divided in about 100 PDF files).

There are no other Problems, no warning lights, no errors in OBD-II. Just these noise, wich makes me crazy :confused: :(

Transmission fluid level is a bit higher than it should (checked HOT), Oil level is perfect, 93% live remaining.

1. Does someone have an idea or a similar problem?
2. Does it damage something, if not fixed soon?

It does not have something to do with my Problem, but:
3. Does it make sense to change the lower drive belt, cause of some cracks in the belt splines (2nd picture)?


EDIT: Its the LT 5.3 V8 engine!

Thanks up front, Marc.

https://cimg8.ibsrv.net/gimg/chevrol...f353ebdb02.jpg

https://cimg3.ibsrv.net/gimg/chevrol...cc3df89e78.jpg

Here is the serpentine belt diagram
Attachment 9862
The 2nd belt looks bad. Replace it. Don't wait.

Okay i ordered one, thanks for picture :). I saw it's just for A/C. Because of the whining sound, it's been located at the alternator, and while driving today, another problem with alt appeared.

If I'm driving the car ( or running eng on park ) and the DRL or the parking lights are one, the whole voltage drops to 12.5V, if the whole beams (passing lights) are on, the voltage is on its 14V defaults. But it really depends on lights. What I'm wondering about, that on parking lights all lights are on, instead of headlight beams. And it goes to 12.5V. If the beams are also on, it works as it should?