Checking Rear Wheel Bearings

[Phillip]

I'm getting some rumbling noise from the back of my '99OBW and suspect a bad wheel bearing. I tried jacking up all 4 wheels in an attempt to listen to the rear wheel bearings with a stethascope, but the rear wheels won't spin (only the front). If I accellerate hard on gravel, both front and rear wheels spin, but not with the car jacked up. Question? how can I check the rear wheel bearings?

[porcupine73]

Maybe a dumb question, but are you sure the e-brake is off? I have haven't noticed not being able to turn the wheels as you describe on either of my AT Suby's; even with just the front or back jacked up I can turn the tires by hand. One thing to check might be trying to wiggle the wheel in all directions and try to slide it in and out feeling for any free play.

[DerFahrer]

The only way to "diagnose" a bad wheel bearing is to listen for the sound you mentioned. They are sealed and can't really be checked without removing them.

 

Besides, jacking the car up to let the wheels spin freely will not only take the weight off of them and therefore cause them to be silent, but wheel bearing noise usually isn't audible until about 15-20mph anyway, so just letting the engine idle the free wheels along won't make the noise happen at all.

[bgd73]

When in doubt replace them. It is a noise to clearly indicate it.Go for another brand aside from subaru, if after cleaning old ones, they look pitted or yellowish. I went though this on my 2wd. The 4wd's may have got some bad too, especially if you find they are greased well.The after brand was at least looking like steel bearings.

[ronemus]

Before replacing the bearins, check the runout on the rear disks - it can sometimes be confused with bad bearings.

[johnceggleston]

when you have it on jacks, put it in 1st not d. rumor has it that in 1ST there is a 50/50 split of power. next i would try apply the brakes, this might make the awd kick in.

 

I'm getting some rumbling noise from the back of my '99OBW and suspect a bad wheel bearing. I tried jacking up all 4 wheels in an attempt to listen to the rear wheel bearings with a stethascope, but the rear wheels won't spin (only the front). If I accellerate hard on gravel, both front and rear wheels spin, but not with the car jacked up. Question? how can I check the rear wheel bearings?

[cookie]

A subie mechanic who posts here when he is not busy said he checks them on the lift by rolling the tire and putting his hand on the spring to feel the vibration.

[Manarius]

When my wheelbearing was toast, it was definitely noticeable - you can't ignore something like that. I think that if you need a stethoscope, something else must be wrong.

 

I'm a big fan of the lateral movement method - jack up the car and either kick or shake all 4 wheels. None of them should move laterally at all if kicked or shook. By laterally, I mean that if you're looking at the wheel, it shouldn't move away or from you, it should be absolutely tight to the hub. Also, if you take off the wheel of the suspect bearing, there should be a good amount of play in the hub itself - the lug studs should be pretty easy to shake, and they should move a good bit.

 

I wonder if you have a dragging dust shield. I'd certainly check that before you get into bearings.

[cookie]

I've seen many forms of wheel bearing failure in my years as a bus mechanic. When they start to go you have no visable play. The first thing tends to be plating flaking off the surface and it will show up as sound and sometimes you can feel roughness at that point. After a while the rollers or balls start to disintegrate and you can feel play at that point. If you continue to drive it becomes a thumping sound and you can feel a good shake. The final stage is the wheel in the road syndrom.

I've torn down a number of them that had no symptom at all and we could spot wear and the begining of flaking on them on inspection. In the old days you actually serviced and inspected these things on a frequent basis as the seals and grease were not capable of 100,000 miles or more like today.

[xrturbo]

that is funny that i just jumped on now and saw this on my lunch break. i just got done doing a rear hub assembly on a 97 obw. all the other wheels spun but that one, i just gave it a helping spin and a little gas while it was on the lift.

[cookie]

So we may be learning that one failure mode for Subaru wheel bearing might be binding?

[Manarius]

So we may be learning that one failure mode for Subaru wheel bearing might be binding?

No, binding is very different from a dragging wheel. Biding is almost always drivetrain related.

 

Wow though, that bearing must have been near seizure if it was that bad. What did the person do, drive it for like 15k miles with it grinding and acting up? Sheesh.

 

Did the bearing finally start disintegrating and tear up the hub? Is that why you had to replace it?

[cookie]

I have seen bearings fail to the point where they weld together and spin and ruin the hub. I have not yet seen one bind without welding, but I suppose there may be a point where they do that.