2001 bmw x5 - whistle sound coming from under the hood when accelerating!
 

i have the 2001 bmw x5 ,4.4l
and for few days now ,for some reason i dont have a clue and i cant find from where is coming from,there is a whistle sound coming from under the hood,when accelerating or when i put in drive to go,based on how much i push the gas the sound goes higher,but i think from 20-25 mph and up i cant hear it no more.

here is a link to a small video:
video one:
here

and video two
here

anyone had this problem?,i just cant find where the noise is coming from!
it maybe from somewhere related to air ? vacuum...

also sprayed some belt stuff to see if is from the belts ,but it was still there the sound,checked all fluids ,all okay.

at this point dont know where else to look !

thanks for any advice!

regards,
bosanci28

If I'm NOT mistake, thats Alternator whine. I believe that means your alternator is going to quit soon.
Can anyone confirm this?

hmm,replaced 4 months ago brand new!...($400)

Sounds like you've got a good turbo in there :P

There is an easier way to find out what it is rather than posting a video from behind the bonnet. Grab yourself a long flat head screwdriver and while the engine is running put the handle against your ear and the other end place it on different sections of the engine (Exactly like a stethoscope) or even better get yourself a mechanic's stethoscope. It'll be quite obvious to you when you get close to the cause as it will be very distinct and loud. I suspect its a bearing of some sort but from your video it's hard to tell.

Be careful not to get in the way of the belts or moving engine components while doing this.

hi,
yes i do have one of those,
hmm,thanks for reminding me,i forgot about that tool.

i guess it must be a bearing ... maybe a loose belt and the bearing will do that because of it,will have a better look in the morning.
thanks for replying friend!

will check that tension-er ,to see if there is the problem,
thanks for that video link!

No dramas, let us know how you get on

okay ,i will ,thanks...

wow,i guess that noise sound ,did other thing on me today!
i did not have the chance to diagnose the whistle problem,and i was going to do it today,

now this morning when i start up the x5,i got red "battery light" at dashboard!,put my tester in (this one here),and i got only one red light in the battery side,but nothing else is on,
normally if on red light is on ,on the battery side (tester) that means battery maybe bad or is not charged.
now on the tester at alternator side with car running "no lights" at all!
i think that noise,whistle it may come from the alternator !,no lights on the tester,whistle problem, i am guessing now that my alternator is failing again only after only about 4-5 months of use?!!?,wow...
because if the alternator will it work,i suppose to get "normal light "on ,at the alternator tester side.

oh,brother ...all this are coming,just now...