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-   -   2007 3.0 auto strange oscillating sound (https://www.bimmerfest.com/forums/showthread.php?t=1315211)

aperrin 01-29-2019 09:28 PM

2007 3.0 auto strange oscillating sound
 
Hey all, first post here. I have been reading this forum for a while, although I have not yet contributed. This x3 is my first car (after years of riding/DIYing all kinds of mopeds/small motorcycles), and I absolutely love driving it. I have been trying to figure out this issue for a while, and its starting to make me uncomfortable about taking the car on long drives.

Its 2007 X3 3.0 Auto with a very very strange sound...Its a mid/high pitched oscillating sound that changes in pitch with vehicle speed (not RPM). It is NOT reproducible in neutral. The sound is not constant, but I have noticed patterns of when it will occur (although it still seems to be random on how loud/often).

It happens the most while coasting on deceleration, but also while accelerating around 2nd and 3rd gear. Sometimes the pitch is a constant singing sound, and other times it is more warbly and definitely sounds mechanical. Here are some videos....

Oct 22 2018:
https://youtu.be/5Y0HPibHsvM

Jan 29 2019
https://youtu.be/GCtycVz7mB4

The sound started happening shortly after I had my indy (who is amazing) replace the rear driveshaft that was completely rusted, change the T-case fluid, and change one of the VANOS solenoids (to clear a code). All of this made a huge difference in drivability, but also caused this weird sound.

That was back in September and the noise has not gotten significantly better or worse since then. I havenít noticed a loss of drivability except for a slight hesitation on throttle and maybe some delayed shifting while climbing hills. It is still way better than before I had the driveshaft and T-case fluid done. I really trust my mechanic, but he is stumped on this one too. He thinks its probably the stupid built-in PCV on the valve cover, although hesitant because it is not reproducible in neutral. He said the only way to tell if its the valve cover is to see if it gets worse, because it inevitably would (which it hasn't in nearly 4000 miles).

I had him change the front diff fluid just in case, but that didnít seem to fix it eitherÖ.So I was wondering if anybody had ideas! Could it be gear whine from the transmission or transfer case? Or could it be that it is the valve cover and the sound is only occurring at very specific engine pressure...

I am open to any ideas...thanks!_a_

aperrin 02-13-2019 03:58 PM

The sound hasn't got better or worse...nobody has any ideas?

frisbeeguy 02-13-2019 05:47 PM

I don't know....I'm stumped too. :cry: Sounds like whale mating calls.

As for PCV testing see this thread: https://www.e90post.com/forums/showthread.php?t=1421986
post #'s 16 onward...Post 17 for PCV testing.

dukedkt442 02-13-2019 05:53 PM

It does sound Like a PCV whistle. How difficult is it to remove the oil cap with the engine running?


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mchova01 02-13-2019 09:59 PM

Unless you are off-roading in the videos, the suspension looks awful. I didn't realize how bad mine is until I got an brand new VW Atlas.

I'm working on figuring out the best suspension revamp.

I do not have any idea on the noise. I never heard it before.

BimmurBrothor 02-14-2019 12:22 AM

I hear the sound...."eerie" ***128561; Seems to me i heard this sound from a much larger type trucks and from the drive train or transmission. Have you mentioned the status of the transmission? But again you did highlight that this sound started around when you had the drive shaft replaced...on my first hearing the thought occurred to me that something is too tight! But again it was a quick notion.

06 X3 199k
05 X3 181k
04 X3 162k

mtbrdad 02-14-2019 05:19 PM

My guess says it's the aftermarket driveshaft I had the same noise. Here's my thread on it https://www.bimmerfest.com/forums/sh....php?t=1248498


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