2008 Legacy Diesel - rear (right?) noise
 

Hey guys,

I'm in Switzerland and have a 2008 Subaru Legacy Stationwagon (2.0 Diesel), and it make this noise at 70 to 80km/h or above. It almost sounds like a small motorcycle is following me. I'd describe it as a low pitch whine/groan that increases in pitch and loudness with increased vehicle speed.

The car has 118'000 km on it, and at first I thought it could be the rear diff. So just today I drained the rear diff fluid, and although it looked used, there were no obvious metal shards/pieces in the oil, and the drain plug magnet was actually quite clean with very very little dust on it. I filled it back up and went for a quick drive.. noise remained. My only other thoughts are that it could be the wheel bearing. The CV joint looks good, the driveshaft feels solid with no play.

Since the car has almost 120'000 it's time to change the front diff and transmission oil as well, and I'll be tackling that one maybe next weekend. I've got wind of a guy who has a barn with a car lift that I may be able to use. That would greatly simplify the work if I can get him to agree for me to use it.

Anyway... any thoughts on this? The only other thing it could be, imo, is the wheel bearing, but I've never heard a bearing make that kind of groaning noise before.