1996 Outback 5spd 2.2. 198,000 miles.

 

I've been noticing a whirring noise coming from the rear that sounds almost exactly like tire noise. Rotated my tires and the noise is still coming from the rear. It used to be pretty constant, then I took it out in a gravel parking lot and did some drifts and doughnuts and now it's much louder when engine braking. Jacked up the rear and don't notice any movement in the wheel so not leaning towards wheel bearing. Haven't checked fluid in the diff, though I probably should. If it's low, should I go ahead and replace diff or will it be fine if I just drain what's in there and refill? Thanks guys.

Check the fluid in the diff first for sure. It doesn't sound good but a fluid change may help. It uses just shy of a quart of fluid so a change is cheap and easy. Thank the genius designers at Subaru for putting a drain plug on the thing! My Lincoln has a similar style mounted rear diff with no drain plug. Draining requires either a fluid evacuator or nearly removing the diff to get access to remove the cover.

 

Catch the old fluid in a clean container so you can check for metal shavings. More than likely it will have some. Most of the time some of that is OK, but if it looks like liquid silver, you have some real damage going on inside and should replace the diff.