Who is whistling under my hood.

[1BADM6]

Had an interesting week. My truck left me stranded...again, so I figured if I'm going to wrench on something it might as well be nice, comfortable and fun to drive. After reading up on a multitude of issues involving higher end SUV's in my budget I decided they all have their issues and since I've been bimmerless for 4 years I might as well see what's out there. I immediately stumbled on this mint, 2002 4.4l in Topaz Blue/Beige/Light Poplar with cold weather and premium packages. At 133k on the odo it still has some life left in it but no, the TCG's have not been replaced but driving this thing was like putting on an old pair of jeans, comfy and tight. I do have every maintenance record since day one and it runs and drives like a dream except...for the whistling under the hood and of course the rear air suspension. Yes it's inactive. First things first though. I think the whistling might be the CCV if I remember correctly. When I get a chance I will get it scanned. Full fluid changes will commence this week.

I'm excited with some trepidation. Cheap BMW's are not usually cheap for long. I only had to relinquish 4k for this one(knocks on wood, crosses fingers, says a prayer, holy mother full of grace, checks reserve funds). I've been reading a lot on this forum in the last few days, great info and great community. Thanks to all who have contributed their hard fought knowledge for others to follow. I'm looking forward to future interactions.

[80stech]

whistling all the time ?

[1BADM6]

Not immediately. I don't really notice it inside the cabin but pop the hood when it's warm and it's a shrill, constant whistle. Sounds like an air leak through a torn diaphragm or a cut line. Pretty sure it's CCV but I haven't had time to do any sleuthing yet. Tomorrow afternoon I'll get on it.

[upallnight]

If it sounds like "Dixie" that Johnny reb under the hood.

[RenaissanceMan]

Originally Posted by 1BADM6

Not immediately. I don't really notice it inside the cabin but pop the hood when it's warm and it's a shrill, constant whistle. Sounds like an air leak through a torn diaphragm or a cut line. Pretty sure it's CCV but I haven't had time to do any sleuthing yet. Tomorrow afternoon I'll get on it.

Don't have an answer for you yet, but I am following this thread with much interest. I have the exact same high-pitched whistling noise that varies with throttle application coming from my motor. Interestingly enough, it's started immediately AFTER I replaced my cracked CVV and related hoses. I have smoke tested the motor, scanned for codes, and done other tests and cannot find any evidence of a vacuum leak. I'm not really sure what to check next. Car is running perfectly but the whistling is driving me crazy even though it's not that loud. My long-term fuel trims are also hanging out a little high between 1.6 and 3.7 on any given day, but again I can't seem to find any vacuum leaks whatsoever.

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[Fifty150hs]

Originally Posted by RenaissanceMan

Don't have an answer for you yet, but I am following this thread with much interest. I have the exact same high-pitched whistling noise that varies with throttle application coming from my motor. Interestingly enough, it's started immediately AFTER I replaced my cracked CVV and related hoses. I have smoke tested the motor, scanned for codes, and done other tests and cannot find any evidence of a vacuum leak. I'm not really sure what to check next. Car is running perfectly but the whistling is driving me crazy even though it's not that loud. My long-term fuel trims are also hanging out a little high between 1.6 and 3.7 on any given day, but again I can't seem to find any vacuum leaks whatsoever.

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Have you checked your tensioner pullies? They can sound like whistling when the bearings go bad. When mine went it sounded like I had a flute under the hood!

[RenaissanceMan]

Originally Posted by Fifty150hs

Have you checked your tensioner pullies? They can sound like whistling when the bearings go bad. When mine went it sounded like I had a flute under the hood!

I will check!

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[1BADM6]

Originally Posted by upallnight

If it sounds like "Dixie" that Johnny reb under the hood.

Haha! Not quite. More like a dog whistle. It's been so wet in Seattle and since my garage is full at he moment I went ahead and ordered the CCV/PCV/EGR, whatever it's called, doohicky. It seems every parts place calls it something different. I ordered rechargeble batteries for my key fobs and I think I may know the cause of my air suspension not working, water beneath the spare tire. Yep, got a leak somewhere.

You tube is f**king great. This video nails it the sound.

https://www.youtube.com/watch?v=nSOgkGqfZ2E

[1BADM6]

Originally Posted by RenaissanceMan

I will check!

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Although I'm new to the M5 I bet I've spent 40 hours in the last 4 days reading everything I could on them. The alternator can also make a whistle or whine that changes with RPM before it dies. Probably a bearing.

[andrewwynn]

Ouch on the sound that's not a whistle it's metalic scrape. Sounds like a bearing to me.

I use an app called FFT on my iPhone. It will show a graph of all the frequencies at once so you can see the frequency center of the peak. Pan the phone around or better use the headphone mic you can tape to a stick. You can determine exactly where the sound is sourced.

Rattle sounds I didn't hear. You can often find the bad bearing by taking off the belts and turn each appliance and pulley.

The minor "rattle" in this video sounds like valve train normal noise of lifters and valves. Listen on initial cold start: if you hear tapping that settles to the rattle in the same tempo it's likely just normal valve train noise


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