Hi, I recently purchased a 2011 Cayenne Turbo. On the way home, I noticed a high-pitch "whistling" sound at low speeds, usually around 20mph - this happens when coming to a stop or soon after setting off from stopped. The sound only lasts for a second or two, and doesn't happen every time.

The audio is difficult to capture on camera but here are 2 videos:

https://imgur.com/myvUGWN
(light acceleration, noise happens at around 20mph)

https://imgur.com/iDuCM3T
(the noise happens on deceleration this time, again at around 20mph)

Despite the noise sounding a bit like a turbo, it also happens off-boost, and only at low speeds. It sounds more mechanical in real life, something related to the drivetrain I suspect.

Has anybody had similar issues in the past before I investigate further?

Thanks

 

12 months later, an update.

This whistling noise was coming from the transfer case. Locking the centre-diff made this noise much more pronounced, and unplugging the electrical connector to the transfer case stopped the noise completely.

I was planning to replace the transfer case, but the real fix happened to be much simpler: the previous owner had fitted the wrong tyres on the rear.

When I purchased it last year, the car had 295/35/21 on the front (correct), and 315/35/21 on the rear (not correct). I had noticed that they were different sizes, but just assumed the car used a staggered set-up like the newer model Cayenne. I recently discovered that this is not correct, and the 958 always uses a square set-up.

The difference in overall diameter between these sizes is only 15mm, but this must have been enough to confuse the transfer case and force it to work harder. After fitting new tyres in the correct size, the noise immediately went away.

 

Maybe worth changing the TC fluid.