I have had 2 cars with exactly the same problem. The first was a 1998 Volovo V70XC. andthe second is my current 2003 BMW 325Xi - both AWD. When driving say on a freeway at 60 mph and you touch the accelerator to apply power, you get a whining or slight howling sound. As soon as you lift, the sound disappears, but each time you touch the pedal, the sound reappears. It seems to be coming from the driveline toward the mid to rear of the car. As you accelerate to 65-70 or decelerate to 55-50, the phenomenon disappears. What is causing this and how can it be fixed?
Both cars have very complex awd systems. Have it checked by an independent mechanic who specializes in BMW. Dealers can be $$$$$$!
So, did u ever have any issues with Volvo besides whine? Did the whine lead to a driveline problem? If not, than u never really had a problem?
I would have a BMW dealership change all the fluids in the various gear-boxes. That’s the only way you can be SURE the correct lubricants will be used…If the drain plugs contain magnets, ask how much metal was found on those magnets…Explain to the service manager the noise you are hearing…Good Luck…
I think those are all good answers. The Volvo has a rear multi-plate clutch “on-demand” system while the BMW has a center open-differential system. The Volvo only engages the rear as required, the BMW has a real full-time AWD system. Other than making sure the fluids are clean, there is nothing to worry about unless it gets worse over several thousand miles. I suspect though, that you are just in tune to the gear meshing whine and there’s a good chance it’s normal.
A whine in the differential at a certain range usually points to wear on the ring and pinion gear. Any rumbling or whirring noise could point to worn differential carrier bearings. Either way it can be bad news.
Lack of fluid changes, running mismatched tires, etc can contribute to problems like this.
I always get an “unnecessary” whine driving 60 mph too. But only in a 55 mph zone and only from my wife who thinks I’m driving too fast…