acarpenter86
06-04-2021, 09:52 PM
I’ve been trying to deduce a strange metallic rattling sound for a bit on my 335xi. It was for the most part only happening on cold days. At around 30mph, I’d get this crazy rattling sound all of a sudden. If I sped up, it would go away after around 40mph. However, if instead of speeding up I were to slow down from 30, it would decrease in “speed” matching my vehicle speed until I stopped. Then it wouldn’t return until 30 again. After ten minutes of driving it would stop, period.
If I were rolling and shifted to neutral the noise would still follow vehicle speed, not revs of the engine.
I was thinking CV axle since I had replaced a boot. Maybe it failed. Well, now I’m not so sure.
Sometime it randomly seemed to change. Instead of a slower, speed related rattle, it’s kind of like around 35-40 I let loose some ball bearings on a bumpy metal baking pan and shake it around. It’ll continue until I reach around 50-60mph and gradually die down and disappear. I knew it wasn’t going to go away on its own, but maybe this will help me narrow it down.
Lastly, I noticed today that if I back up my steep driveway, it kind of sounds like “whump whump whump”. A low pitched sounding groan.
Car has recently had a transmission fluid, filter, and sleeve service. Shifts are super smooth.
Front and rear differential as well as transfer case fluids are less than 3k miles old.
I changed the power steering pump 1k miles ago. (So smooth now. One groan gone!)
2008 335xi e92 with 211k miles.
Audio clips I’ve captured so far:
https://youtu.be/I6SRNrIXsew
https://youtu.be/L8p68-h-kLc
https://youtu.be/sBlSnP9T6lQ
If I were rolling and shifted to neutral the noise would still follow vehicle speed, not revs of the engine.
I was thinking CV axle since I had replaced a boot. Maybe it failed. Well, now I’m not so sure.
Sometime it randomly seemed to change. Instead of a slower, speed related rattle, it’s kind of like around 35-40 I let loose some ball bearings on a bumpy metal baking pan and shake it around. It’ll continue until I reach around 50-60mph and gradually die down and disappear. I knew it wasn’t going to go away on its own, but maybe this will help me narrow it down.
Lastly, I noticed today that if I back up my steep driveway, it kind of sounds like “whump whump whump”. A low pitched sounding groan.
Car has recently had a transmission fluid, filter, and sleeve service. Shifts are super smooth.
Front and rear differential as well as transfer case fluids are less than 3k miles old.
I changed the power steering pump 1k miles ago. (So smooth now. One groan gone!)
2008 335xi e92 with 211k miles.
Audio clips I’ve captured so far:
https://youtu.be/I6SRNrIXsew
https://youtu.be/L8p68-h-kLc
https://youtu.be/sBlSnP9T6lQ