So a noise popped up today on my 430 4matic. Not sure how to describe it. When under medium acceleration I'm getting a squeaking/chirping noise. The noise speeds up with the speed of the car and disappears when I ease up in the throttle. When cruising and I hit the throttle it doesn't squeak but it does sound like a chatter. And if I manually downshift into second or first the noise is there as well. Another thing I noticed is occasionally the past couple of days when going from reverse to drive or vice versa something under the car lightly pops and then you hear ping. Similar to the sound the exhaust makes when a rock or debris hits it. I sure the two issues are linked. Just not sure what it is. Propeller shaft flex disk? U-joint (s)? Center bearing? Has anyone else ran into anything like this?

 

hard to guess behind a keyboard whereas you can get eyes on your flex disks and checking the undercarriage in minutes.

 

No noise in neutral when reving or when I have it in drive or reverse and power braking the car. No unusual vibrations either.

 

Update....... the noise has turned into an consistent chirp at cruising speed on the throttle and after putting the car on a lift and not being able to replicate the sound I had someone drive next to me so we could determine where exactly the noise is coming from. Turns out its coming from the both front hub assemblies. Tried using some pb blaster and white litho grease and sprayed down different moving components to see if I could quiet the chirp. To no avail the sound is still there. I'm assuming that it probably wheels bearings at this point. Note: the sound neither changes pitch or goes away with braking.