Diagnosing a bad wheel bearing

[Phillip]

My 1999 OBW is making a rumbling sound that I suspect is a bad wheel bearing, but I can't locate where the sound is comming from. The sound is constant with the steering wheel in the straight position or when turning right. If I move the steering wheel slightly to the left, the noise nearly disappears.

Thinking I could find the noise with a stethascope, I put the car on jackstands and had an assistant accelerate to 40 mph. Unfortunately, only the right front wheel spun. I know I've got power to all wheels as I can spin both front and back wheels on gravel. Is there a way to 'fool' the AWD system and make front and rear wheels spin when jacked up?

[OB99W]

You may already have a hint as to a possible problem. The AWD system determines front/rear power distribution, not left/right. For the moment, I would ignore AWD and that the rears wheels aren't turning, and question why, of the two front ones, that only the right is moving. All things being equal, you'd normally expect the front differential to be turning both wheels at about equal speed. However, the differential seems to be favoring providing power to the right side, which may mean the left has excessive friction. You might see with the engine off and the car in neutral if you can feel a difference when manually trying to rotate each front wheel.

 

If there's a frictional cause of only one wheel turning, sometimes it can be countered by gently applying the brakes, which may equalize the drag somewhat. Once more than just the one wheel is turning, you may be able to then release the brake and have more than one continue to spin. Of course, ABS might come into play. If you notice it being actuated during your diagnostic efforts, you might temporarily pull the fuse(s); the owner's manual indicates numbers 18 (ABS control) and 19 (ABS solenoid) as being relevant. Of course, replace the fuses before any road usage.

 

By the way, be careful when powering the wheels while on jackstands. If only one wheel is turning, it's going to be rotating at a road-speed equivalent of double what the speedometer would have you believe. That "40 mph" is effectively 80 if only one wheel is turning, and that could be dangerous. Even at 40, any stones, etc., that might be lodged in the tread could be thrown and cause damage/injury.

[Manarius]

Jack car up.

Check to see if wheel moves laterally (left-right).

Wheel should not move at all. If it does, you've got a toasted bearing.