Weird High Pitched Whistling Noise at Idle (E46)

[Perfect 50 50]

Hi everyone,

This is my first post on bimmerforums and I have a problem with my 2005 325Xi I'm hoping you can help me with.

My car is making a high pitched whistling/screeching noise at idle only and I can't seem to figure out what it is. It happens when the revs drop below 700-800 RPM. Once again, it stops only when you give it a little gas and it goes above that RPM level (almost 1,000). I've tried an oil change and had it inspected at a reputable indy BMW shop and they said everything was fine (oil sep, ICV no rips in intake boot or vacuum lines etc) and couldn't figure it out because it happened to not make the noise while they were checking it out.

Has anyone experienced this before? Any info will help.

Some facts about my baby:

2005 E46 Xi 65000 miles, no check engine lights. Let me know if you have any questions..

here's a link to a YouTube video I posted that shows the sound it's making. [ame]http://www.youtube.com/watch?v=Wy9LzZ312TY&feature=youtube_gdata_player[/ame]

In the video, the sound stops on its own which it does from time to time which explains why my mechanic couldn't figure it out

[WoLF]

I would guess and say it's one of your pulleys.

Remove the main belt and spin the idler and tensioner pulleys. If they sound like skateboard wheels, you need to replace them.

I'm baffled as to why your mechanic may have not checked them...

[Perfect 50 50]

I thought of the pulleys but I was told if it were the culprit you would still be able to hear it when you step on the pedal and give it some gas, which I was told it would get a higher pitch/louder etc.

[Perfect 50 50]

Thanks for your post but what's described in this post is different from what's occurring in my situation. The sound my E46 is making is only at idle, and goes away with any throttle above 1000 RPM.

Post 1 on that forum:

"I have an odd "whistle" noise at low throttle. It is not present at idle (zero throttle) or at any throttle over, say 15%. It only occurs when driving leisurely with light throttle pressure (like up a very slight grade at 25mph)."

(where mine is at idle only)

"It is high-pitched. The pitch does not vary with RPM's. It just starts with a little throttle pressure and goes away if you let off pressure or give a little more pressure."

(which this is also true with the noise coming from my engine as it does not change pitch, though it does on it's own get quieter or louder)

"I do not think it is a squeak or squeal, it is more of a whistle as if produced by air, not metal or rubber.
NO check engine light.
It sounds like it is from engine compartment, not chassis."

(all of this also true with mine)

Ideas?"

It's possible that I can be getting my noise at a much lower rpm band and I will be checking that post and other posts for a video of some sort of the actual sound it's making to compare.

Thanks for all your ideas. Keep em comin!!

[WoLF]

I maintain my advice of checking the pulleys. It's rather simple to take the belt off and spin the pulleys.

Checking them will definitely give you a solid yes or no.

You seem to have already covered the other major sources: ICV, oil separator, intake boots, vacuum lines. The pulleys would be the next source to check.

[danewilson77]

I maintain my advice of checking the pulleys. It's rather simple to take the belt off and spin the pulleys.

Checking them will definitely give you a solid yes or no.

You seem to have already covered the other major sources: ICV, oil separator, intake boots, vacuum lines. The pulleys would be the next source to check.

Agree.

[CakePie]

I'm guessing the indy shop didn't remove thelower intake boot to inspect.

Sent from my SPH-D710 using Tapatalk

[Perfect 50 50]

I'm guessing the indy shop didn't remove thelower intake boot to inspect.

Sent from my SPH-D710 using Tapatalk

They said "it wasn't the intake boot" but wasn't sure how much they delved into it

Was the noise in the video I posted [ame]http://www.youtube.com/watch?v=Wy9LzZ312TY&feature=youtube_gdata_player[/ame] the same as something you've experienced with the lower intake boot?

Agree.

I will have the belt removed and have the pulleys checked and a more thorough exam of the intake boot next.

[Perfect 50 50]

Just an update. Had the idler and tension pulleys replaced today at TMS. Since the sound only happens every once in a while I'm gonna hope its fixed until I hear it again. In a few days if I don't hear it, I'll post it up. Til then, fingers crossed.

[Perfect 50 50]

Update!!! I have not heard the noise for three days after getting it fixed! It def was the pulleys!! WOOO HOOOO

Oh btw.. 100th post

[betaflame]

Update!!! I have not heard the noise for three days after getting it fixed! It def was the pulleys!! WOOO HOOOO

Oh btw.. 100th post

I had this exact same issue, if I'd seen the thread I could have told you :P

[Perfect 50 50]

I had this exact same issue, if I'd seen the thread I could have told you :P

I'm so happy that the noise is gone though. It was so annoying. After that and getting rid of the CDV it feels like a new car.

[Bufftron2000]

My Vehicle just recently started doing the same thing. Not a squeak,squeal,or grind, just an odd whistling kind of noise that comes and goes but when you give er a little gas it will go away. I've been told harmonic pulley, power steering which it almost sounds like a power steering whine but it is fine. if you could repost your video of the sound that would be very helpful

[smeli]

its most likely you idler pulley or main belt tensioner pulley. very common

[max e46]

I have a similar problem but the sound gets louder when i turn the ac on