Help diagnosing a problem

[SixOp]

Hello everyone. First time poster....long time lurker. Over the past year or so, I have come to rely heavily on everyone's expertise in dealing with matters for my 2003 X5 3.0l. Recently, an issue arose with my X5 that has me completely perplexed.....so I need some advise.

About two weeks ago I was slowing down for a stop light and I heard a horrible noise coming from my front end that sounded like a wheel bearing that has completely failed. The noise starts at around 8mph and doesn't go away at any speeds (although the noise is so loud that I haven't taken the x5 above 30mph). The noise is constant and doesn't vary in sound even if I steer left or right. I had the X5 towed to my house and start to diagnose the problem.

I've jacked it up just to find that there is no play with either front hubs or that my brakes are dragging and the pads look fine. I also found that my driver's side outer CV boot was ripped, but I don't think that would be causing the sound. I decided to go ahead and run it for a short period on jack stands to see if I could replicate the noise. The following is what I have witnessed:

1. Start car - everything fine
2. Put in drive - back wheels start to spin...everything fine
3. Push gas - front drive system engages around 10mph
4. Noise heard from front drivers side. Immediately think its wheel bearing.

Now, this is where I get confused. I did a test run before I put the car up on jack stands and I noticed that the noise went away while rolling down a slope (not pushing the gas pedal). As soon as I put some gas to it, the front drive train kicked in and the noise came back.

Shouldn't the noise be there if it is from the wheel bearing whether I apply the gas or not? Does the wheel not roll on the same bearing whether the front diff is applying torq or not? Could a torn CV boot or bad axle make that noise? Should I be looking for something else entirely like bad front drive shaft/transaxle?

Soooooooo lost. Any help is greatly appreciated!

[upallnight]

Look between the rotor and dust shield and see if something like a rock might had gotten wedge in between them.

[SixOp]

Thanks for the reply. I'll take a look.

[SixOp]

No rock or anything else wedged in there. Any other suggestions?

[4.8isX5]

Since your saying the noise happens when your on the gas, id take a look at the CVs make sure the splines are still ok, can be a front diff issue, or perhaps even transfer case although im not familar with the tcase on the pre xdrive ones.

[SixOp]

Originally Posted by 4.8isX5

Since your saying the noise happens when your on the gas, id take a look at the CVs make sure the splines are still ok, can be a front diff issue, or perhaps even transfer case although im not familar with the tcase on the pre xdrive ones.

Any easy ways to check these or am I ripping prions of the front end off?

[swissfrank]

sounds like the splines on the front drive shaft have worn out.

the fix

or some people use spacers to push the drive shaft back a little further.

[SixOp]

What kind of spacer do they use?

[SixOp]

Also, is there a way to check for this? Drive shaft play/slop?

[swissfrank]

Lots of good info here

The best way to check is to pop the drive shaft off, the front drive shaft is under the driver side front door. If that is where the noise comes from it sounds like the culprit.