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Old 01-29-2019, 09:28 PM
aperrin aperrin is offline
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Join Date: Jan 2019
Posts: 4
Mein Auto:
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:

Jan 29 2019

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_
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