Tips on detecting a blown wheel bearing?

[OldManHenry]

I jacked up the rear end of my new-to-me '91 325i tonight because I've been hearing a rubbing/grinding noise from the back end of the car on slow speed turns in the parking lot, for example. I've read that this could be because of bad wheel bearings and also potentially a failing differential. I had seen on "wheeler dealers" that the mechanic was grabbing a wheel and was able to shift the wheel by tugging on it. I can't do that to either wheel... is that a valid method or should I try something else before moving on to the diff?

I can swap the diff fluid out, watched some youtube on that and it seems super easy with a torque wrench and see if that helps too.

[jonnywadster]

Heh I'm in the same boat, it could be my diff or my something in my driveline.
I flushed my fluid in my diff to buy some time I'm going lsd by summertime.
Also just make sure you have money for a tow, and yeah it could be your wheel bearings too.

Jack up your rear end and spin your tires out of gear with the brake off and see if you hear any noise from anywhere.
Mine could be wheel bearings or a diff bearing, I'm just going to replace everything this summer lol.

[Delta]

You can jack up the rear end and grab the top and bottom of the tire. If you are able to shake it and get a clunk noise the bearing has play. A bad bearing may not always do this however.

With the car in neutral and parking brake off, spin one wheel with one hand on the coil spring. A bad bearing will transmit a "rough" feeling into the spring and your hand. Do this all around the vehicle.

It can still be hard to tell if it's from the diff or bearing however.

[Ether-D]

I had a rear wheel bearing go bad in my first e30. When it happened to me, it started groaning when taking turns to the left (it was a right side bearing) at 20-50mph, then started making the noise constantly after about 5000 miles. I ended up finally changing it after about 10,000 miles of groaning. So if it's a bearing, you may have a little time to get it sorted.

[agent]

If the groaning is so loud that you have trouble hearing on the phone while you're behind the wheel, it's time to change them.

[meanEG]

they will get louder as you get faster. it will also change when it is loaded and unloaded when turning. if that is the issue than these are your symptoms. I would highly doubt you have a bad wheel bearing if you do not have these symptoms.

now a bad diff bearing, that will be a different story