Just noticed this over the last week or two. It has definitely got worse/louder but seems to have settled now. It can be described as a whirring or whining noise coming from the gearbox tunnel area in the front of the car, say under the MMI screen to driver's foot-well area. A bit like electrical interference noise you used to get when your alternator wasn't suppressed in the old days (for those who remember).
- It doesn't do it on acceleration or whilst cruising.
- It only does it when foot comes off the gas and decelerating.
- It does it in every forward gear and is road speed linked and NOT engine speed linked.
- It stops if you select neutral while slowing down.
- Selecting 'Sport', 'Tip' or 'Drive' makes no difference.
- I have slightly uneven wear levels on tyres front to back (2mm rears & 5 mm fronts).
- Gearbox was flushed/serviced a year ago.
- I have also noticed a slipping/spinning/shuddering from the rear tyres when going really slow and on a tight-ish lock (not sure if this is connected).
- No vibrations, clunking, grinding or any other nefarious noises from anywhere.
- Car drives smoothly and as usual from stationary to 3 digit figures. Performance doesn't seem effected.
- Noise seems to abate at around 10mph when slowing down.
- Above 80-85 it seems to pulse/drone when decelerating until about 70 when it becomes a constant whine.
- Car has done 78,000 miles
- No oil/fluid leaks from anywhere or smells of burning oil.
- Had the transfer box off and new gasket and gear oil last year at same time as gearbox service.
- Yet to check VCDS for any codes. Will update.
Is this gearbox, diff, bearings, cv joints? I think it may be gearbox as it goes completely when in neutral. What do folk think?