High pitch whine
 

Okay so I am a newbie here I have done some work myself but I have not been able to figure out what this annoying whining noise is when I turn on the A/C and the car is in gear? I have made a video with the A/C off and with the A/C on and in gear and you will hear it kick in about the last 35 seconds of the video when I turn on the A/C and place the vehicle in gear. I have my suspicions that its an idler pully going bad but I do not want to spend money guessing. I have new belts to put on and I have already replaced the dreaded PCV valve, and the oil filter housing gasket is next on the list of repairs to be performed. I put new plugs in last weekend also.

Vehicle specs: 2003 E53 3.0i automatic 153,000 miles

2003 BMW X5 Engine Noise - YouTube

sounds like a fan to me :S or is it the cricket sounds u talking about if that then its an idler

The fan noise is not the issue if you listen to the last 35-40 seconds of video, you can really hear it whine its a really high pitched whine sound. almost like a tensioner bearing is going bad.

I would change both of them the idler and the tensioner on my jeep tj I was off roading it didn't even make a round and it exploded lol

Since I have to do the dreaded oil filter housing gasket I guess I should go ahead and order both the tensioner & idler that way I have peace of mind and since we are planning a trip cross the US its not a bad idea to cover all bases thanks...

I have an 03' X5 3.0L. I changed all 3 idler pulleys. A/C pully, belt tensoner pulley and idler pully. alternater is a year old. I still have the cricket sound. It drives me nuts. I've heard this sound from many 3.0L BMW regardless of the chasis it's. no idea what it is yet. Anyone have a clue on this?

So I was finally able to figure out what the noise is... It is the Idler pulley just above the alternator. Bearings were shot, replaced with a new OEM one and its quiet once again. The cricket sound some of you are referring to is probably the whistle of the intake manifold. And almost all 3.0 BMW's seem to do it. My neighbor has a 2004 330i and it makes the exact same sound as my 03 X5:thumbup: