My 10' 957 Cayenne has had a grinding/rattling noise from front left for weeks. The noise is mainly present when turning to the right, and increases in frequency with speed.
I replaced the front left wheel bearing, no change. Then I replaced front left CV axle, still no change. Thinking I could have misplaced the origin of the noise, I replaced rear left bearing, but no luck.
I checked and replaced front diff oil for metal shavings, but looked clean. Same for the transfer box.
At this point I was throwing parts at the car, so I took it to a mechanic for a diagnostic. They used chassis ears and told me the noise came from front left wheel bearing.
This time I changed both the bearing and hub, but the noise is ever present.

This is driving me insane!! Any ideas?

Also, the front air suspension is a bit leaky. I've noticed the car is a tad lower at the front, even after the compressor has kicked in and filled them.

 

How about worn control arm bushings allowing the wheel to angle under the cornering load?

 

I've read about this in other forum posts. I don't notice any play in either control arms, and the mechanic did not note this. But maybe it's hard to check for play on these?

Also a note: when I raise the ride height on the air suspension, the noise is significantly lower.

 

I think that's a good clue. As the suspension lowers, the camber increases and the load on the lower inside of the wheel increases. Ias the car raises, the wheel straightens up and the inside load decreases. I think you may have a worn lower control arm bushing(s).

 

I might just have to replace them and see what happens. Do you think my local mechanic might be able to check for wear? Maybe it got overlooked when the car was in.

 

I would think so. Grabbing the suspended wheel at 12 and 6 and trying to rock it up and down is the play axis we're talking about.

This will also sometimes trigger PSM or ABS faukta as the wheel speed sensor stops seeing the vanes go by when deflected. Any of that happening?

 

No PSM or ABS faults. I also checked for play with rocking at 12 and 6 at all wheels. No movement whatsoever on either corner.

Only fault that triggers consistently is chassis faulty, as the front struts are leaky. But the compressor kicks in after a restart, and the fault clears.

 

could be the front differential, we had the same noise did the same thing, even going as far as to replace the differential needle bearing. Nothing helped until the unit was replaced. We bought a good used one. audi is the same part

 

Checked the fluid for metal shavings, but fluid was clean. Also the mechanic used chassis ears and tracked the sound at front left wheel bearing. Might be he couldn't pinpoint the source and gave up?

I also had the car on a lift, had it running in gear and checked for noise. But apparently the wheels need to be loaded for the noise to appear.

 

I'm gonna try bump this thread again. I've kept driven the car, with no changes to the noise at all. It's been a couple of months now, and it doesn't seem to get any worse. If it was a wheel bearing or diff, I'd wager it would get worse and worse over time (?)

Any ideas? Bushings still best bet?