Soft metallic ringing on acceleration
 

Hi everyone: For the last few months, half the time when i accelerated, i heard noises that best described as a far away/soft metallic ringing somewhere under the hood. There is no noise when you rev up the engine at idle. I can say for sure that it wasn't detonation or pinging noises. Anybody have this problem? Thanks!

Sorry, my car is 2005 3.0

Totally different vehicle I know but I had the “same” problem with my wife’s Buick Enclave, in gear, under acceleration, usually accelerating away from a stop light or goosing it in to passing gear on the freeway it would give me a low, “far off” metallic sound like a small ring or hum even, very low though almost imperceptible if you didn’t know it was there.. I ended up tracking it back to the connection between the downpipe and the flex pipe that connects to the catalytic converter. I soaked the bolts in PB Blast, let them soak for a couple of hours then soaked them again over night, hit them with some gear and chain lube and then tightened them about a quarter of a turn, maybe slightly more and that fixed it. Only thing I can think of is that heating and cooling that joint loosened up the seating and tightening it up a bit snugged everything back down.

Annoying as heck I know, good luck getting yours figured out [emoji106]


2005 X5 4.4i (04/05 build date)
Titanium Silver w/Black Interior

There was an old thread on something similar but it may have been in the e70 thread and it was in the rear differential if I remember correctly. I'll try to find it again.

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I've heard that noise (not on my car though!) - its the rear diff input CV joint. It goes dry and the balls in the CV ping about the joint when you change from forward to reverse or back. It's not an uncommon issue on many Bimmer models...

Not sure that this is the OP's issue...

There are worse things than dry balls[emoji38]

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Watch this at 0:17.

https://www.youtube.com/watch?v=ZWAol58HgMg

If that's the noise yours is making it turned out to be the rear driveshaft flex disc (guibo) or the center support bearing. I did a complete service on the front and rear driveshafts after living with that sound for a couple of years. Has never been back.

CW - yep, that's the exact sound the rear CV (at the front to the rear diff - on the rear end of driveshaft) makes when it goes dry. Did you replace or re-pack this CV when you serviced the driveshaft?

No I did not. I heavily copper greased the front centering sleeve/bearing on the TC rear output shaft (the original had seized on there and took a week to remove). Replaced the guibo/flex disk and the center support bearing. I examined the CV and took it to the shop I used to work at. Owner manipulated it and said not to mess with it, looked good. So I threw it all back in and have had a noise free drive train ever since.

No, i don't have the noise described from the video. Mine is more like the pinging noise that you experienced from detonation but a lot softer. In detonation pinging, the more you accelerated, the worst/louder the pinging. in my case, the soft pinging stayed the same, especially if you maintain cruising speed at 60-70 MPH. if I accelerate harder to pass, the noise actually went away. So under the hood, while cruising steadily at the above speed, what parts or areas could caused the soft ringing? could it be the idle control valve? or pulleys? btw, i already changed the tensioner and the alternator pulleys. I didn't change the compressor pulley as yet. I plan on doing it next. In addition, both of my flex disks are still good - no noise when you put the car in D or R.