Hello forum,

I am having an issue the dealer seems perplexed with, and although I've seen a few posts relating to the same behavior on other models, I've never seen a definite answer (or really any solid ideas). So, posting here one more time just in case anyone has an idea.

I have a 2017 RR Evoque HSE, always dealer serviced, and for a few months now I've had a whirring sound and associated vibration coming from the undercarriage somewhere in the front. I can feel the vibration from the sound in the foot pedals (sometimes even faintly in the steering column), and it is LOUD. It isn't a banging, clanking, clunking sound. Definitely a metal whirring sound, as if spinning gears are rubbing together. The sound is at a constant velocity, as well. It occurs generally at speeds above 30mph, but even at 80mph on the highway if I come off the gas and coast for a bit, it will start. The vibration frequency and intensity, again, does not change with speed. Always the same sound. Sometimes during coast on smooth roadways, it will simply not happen. But on bumpy roads or on a smooth road if I hit a bump, it kicks the whir and vibration off.

It ONLY occurs while coasting, 30mph and above. Acceleration instantly silences the noise and vibration, even just a slight touch of gas. It also DOES NOT occur when driving in 4WD mode. I tested this by changing the selectable driving mode to the Ice/Grass/Slippery Hard Surface mode which kept the car in 4WD the whole time, drove a regular route through town, and it was perfectly silent the whole time. AS SOON as I switched back to General Driving Mode and the car dropped back into 2WD, got the noise IMMEDIATELY.

Thanks for any insights and opinions!

 

Any updates on this issue?

 

Only update is that we suspected the PTU, replaced it, and no change.

I'm now suspicious that it is the transfer case. I'm deciding whether I want to spend the $8k-ish which would be necessary to swap out the transfer case. My extended warranty ran out so it won't be covered.

 

when you say PTU what part are meaning exactly? on this drivetrain the PTU/transfer case the same part. i attached a picture. did you replace the rear differential or haldex? my customer is experiencing the same symptoms as described and states transfer case is making noise. they had the vehicle at another shop. her warranty company wanted a sample of the PTU fluid sent to them. results - no excessive metals found. the noise doesn't sound like the PTU. To me it sounds like chatter from the turbo on decell. due to the long neck on the inlet of the turbo it's hard to check for play there and removing the down pipe to access the turbine side sucks.

 

I guess I mean the PTU - wasn't aware the PTU and the transfer were the same box. I had the same result - my garage checked the fluid and no metal in the PTU fluid. Yet the noise persists.

I have thought about the fact that it COULD be turbo-related, but what makes no sense to me is that when I put the vehicle into 4WD by selecting a different drive mode, there is NO noise, ever. I'm not sure why that would relate to the turbo, unless the turbo is not active (or is active all the time) when in 4WD mode. It would make sense for the turbo to be the cause since (1) metal/gear crunching noise is constant despite velocity (so it is a constant-velocity type of gear), and (2) it only occurs on coast / deceleration. Acceleration (even light gas) immediately silences the noise & vibration.

And yes, already did SOME work on the turbo, and it was terrible.

 

these vehicles are AWD all wheel drive there is no 4wd function the vehicle typically drives in a FWD manner and sends power to each rear wheel, when the rear diff commands by supplying hydraulic pressure to clutch packs in the rear diff. it also has hydraulic lines fed to the PTU to allow a connect/disconnect from the rear drive shaft, to achieve better fuel economy when all 4 wheels do not need the power to them. my theory on the turbo is the noise is coming from the turbine in the within the turbo chattering when coming to a stop. note while the engine is running the turbo is supposed to constantly spin. in this case something is restricting the shaft from spinning, and the noise heard is from the turbine coming to a screeching halt.