HELP: Grinding, ROARING rotating sound coming from rear
 

Was on a high speed run on an open stretch of highway. Got up to about 105. I had to brake fairly heavily at one point because of traffic but nothing serious or emergency type braking. Since that point, it was about 10 mins until I got to my exit. Got off the highway and while slowing down on the off ramp, the car just jerked and slowed down big time as it down shifted. Since then there's a really LOUD rotational noise coming from the rear.

Symptoms include:
My entire neighborhood can hear it
Is speed sensitive
More prominent and apparent throughout the cabin at speeds below 20mph
Above 20mph, it fades a bit
Taking my foot off the gas at speed takes the noise out of the cabin but as soon as the car/suspension settles, it returns to the cabin.
Putting the car in neutral doesn't change the presence of the sound. It goes away slightly but only because i'm taking my foot off the gas. [same sound level]
Engaging drive again, the sound immediately returns to the cabin.
Sounds also like i've got a flat or running on off road tires.
Strong smell of gear oil

Jacked up the rear end and I tried the wheel bearing test of holding the wheel at 12 & 6 and 9 & 3 to move it but there's no movement. Rotating the wheel I hear a scraping noise almost like the pad is contacting the rotor surface. I hear this on both sides.

I've also drained the differential after my short (1mile) drive this morning and the fluid was black. When i did the drain and fill on the weekend prior, i did it cold. For the service I used Valvoline SynPower [full synth] 75w-90. It took approx. 3/4 quart. Today however only 1/4 quart came out..... I stopped the collection when it became a trickle instead of a steady stream.

I've also recently done a brake job with new pads all around, new rotors on the front only and fresh brake fluid.

Some vids:
Noise from inside the cabin

Diff Fluid

Right wheel turning by hand

Left wheel turning by hand

Right side of differential

Front of differential

FINAL UPDATE: This turned out to be my rear differential. It was replaced with a used unit and the car is functioning properly again.

Sound like you got hit in the rear with another car? is that what it sound like?
Your tranny is gone.

Not sure what getting hit in the rear sounds like......but it seems to upshift and downshift OK.

Took it for a drive down the street, popped it in neutral and the sound is still there. Reverse and drive engage like normal. My brother said it sounds like when his differential went. Given the strong smell of gear fluid, that might not be a far fetched idea.

Sorry to hear .. literally. Definitely sounds bad but sounds more like the differential or axle but not the tranny. Just a guess of course. Have you checked your diff. since? Sure there's no leak?

I'm sure more knowlegeable people will post. Good luck and hope its not gonna be too expensive.

You said you just did a rear diff fluid change... was this before or after the problem happened. If it was before, I'd go back and drain the fluid into a clean pan so you can see if there is any signs of metal in there, or worse if the fluid was lost somehow. (I recently replaced the rear diff of an E46 that had the fluid changed at an indy out of state, then drove over a thousand miles to La with the drain plug loose and lost the fluid. the diff was TOAST)

If the rear diff fluid is good you should take a small sample of the trans fluid to analyze as well. (a couple ounces) Also, If one of the rear bearings is going out and has a bunch of slack it can cause grinding noises and real weird brake feel, but you would know if that was the case... I suspect the rear diff myself from listening to the video.

'06 - are you still under warranty?

The diff drain and fill was before the problem. Problem started just this afternoon and I did the drain and fill this past Sunday. It's been 2 days and I've been back and forth to work for 2 days, about 70 miles on the new fluid.

Warranty was up 2 days ago! I bought it used, as-is but the drivetrain warranty is up.

If the warranty is only up for 2 days, they should be able to goodwill the repair.

The dealership is about 75 miles away.... not sure if it would make it.

torque converter?

It shifts fine through 1st and 2nd. And Reverse engages normally, no sounds or clicks or anything like that. I'm not shooting down any theories - just trying to provide supporting info.

It's worth a tow to the dealer, don't you think? Especially when you're only 2 days out of warranty.

I think you have filled in too much oil. Have you followed the correct procedure with the engine running and the correct oil Temperature 35-45 degrees. If you filled up when the transmission was cold, it is too much oil on. it has possibly destroyed a simring or gasket.

As an update, I've been doing some reading and searching on various forums and differential failure sounds way different than what I'm hearing on forums and youtube. That sounds like a high pitched gear whine. This is a low, dragging/grinding noise that vibrates through the floor. From what I've been reading, it could be a wheel bearing. I initially thought, and so does my wife, that the sound is coming from the right rear.

I've recently put new tires on, within the last 4K miles and they recommended an alignment. I had scheduled to take it in to the dealer tomorrow. Since I bought the car, I've noticed that the right rear has a bit more toe in than the left rear or any of the front tires.

Sounds like a wheel bearing but could also be too much backlash on the diff.
I would jack front and rear and set the X down on jackstands.
Should then be easier to diagnose whether wheel bearing or differential.

It wouldn't take much to jack the rear wheels up and shake them down looking for bearing slack. And the rear diff noise would be a high pitched whine at higher speeds...

But it may be worth the trouble to tow it to the dealer for a diagnosis, then when you get the price on what it needs you could then ask about goodwill since the warranty just ran out.

sounds to me like you need to replace your bearings in the back. if you roll to long it will mess up everything. rightnow its just the bearing. ( from what i can hear) its not a easy job but if you do your own work it should be a few hour job.

Thanks so much for the reply guys. I am going to jack it up in an hour or so and check it out. One thing that is pulling me away from believing its the wheel bearings is th smell of burning gear oil. Could this actually be the diff just over stressed or burning bearing grease?

I think it is your UNIVERSAL JOINT.
behind part nr.2 RealOEM.com BMW E53 X5 3.0i Drive shaft, single components, 4-wheel
front part nr.1 RealOEM.com BMW E53 X5 3.0i Drive shaft, front, single parts
oil smell, I believe is a different problem from too much oil on the transmission and now drip down on the exhaust

Took it out for a drive a few minutes ago to warm up the diff slightly before draining. Some more symptoms:

Above 20mph, sound changes and is faded out a bit. Probably because the moving parts are moving faster.

If I take my foot off the gas at above 20-30mph, the sound goes away from within the cabin and sounds its just coming from the outside. It is still aparent and comes back into the cabin as the car/suspension settles. If I press on the gas again, sound reappears prominently throughout the cabin.

At about 30mph, if I put it in neutral, the sound goes away slightly but in the same manner as it does with taking my foot off the gas, which is what i did before putting it in neutral. Engaging drive again and the sound reappears.

It is definitely more prominent and loud below 20mph.

I'm now leaning towards the RWB. Only explanation for the gear oil smell is that the diff is working overtime to move the wheels forward.

Read my last post, posted it at the same time as you.

Thanks Olemaxi. I'm going to post up some more vids and pics in a few minutes. I've got it on jack stands now.

I've just updated my original post with more vids and pics. Looks like I might have found my prob.

Front seal on the diff appears to be leaking.

I drained out 1/4 quart of fluid this morning but on the weekend it took about 3/4 quart fluid. I didn't see the leak until I got to the side of the diff.

Now what??

OK so upon a suggestion from a buddy of mine - I filled it back up with fresh fluid. This time it took 1.2 quarts. As I reversed, I still heard the grinding. Took it for a spin around the block and it didn't get any better....

Any metal filings in the drained fluid?
Start the X while on the stands and drive in gear at slow speed.
I would then listen at the differential or at the wheel with a mechanic's stethescope.

If this procedure scares you then better to take to the $tealer or if you can get a tire place/workshop to use their equipment to get the X of the ground for a small fee and drive in gear.

I dont' see any metal filings in the fluid. However: I called 2 dealerships and spoke to the parts counter and the shop foreman at 1. They both said that the vehicle calls for Castrol SAF-XJ (75-140) as it has a limited slip in it. This is for both the front and rear diffs.

So for 1, I definitely don't have the right weight in there as I used 75w-90 and it had no Limited Slip additives.

Talking to a buddy of mine who has his own race team, he said that the combination of the low fluid level and wrong fluid could have caused one or both of the side diff bearings to go bad and that's actually making the noise.....

Ouch ... I know how it is when its self-inflicted pain. Everybody's gone through that at least once. Keep us posted.

May have messed up the clutches too.
I think the clutches would go before the output shaft bearings/pinion carrier bearings.
If it is diff, I would source one from a recycler. BMW pinion, ring, spider gears, bearings, seals, crush washers are expensive.
Labor may be like 5 hours plus.
Certainly an almost easy DIY if you get complete diff from recycler.

OK so the car is in good hands at a local german car dealership about 4 miles down the road. They sell and service mostly BMWs, Porsches and Volvos. I was actually able to drive it there at about 30mph. Tech drove it about 10 feet and looked at me with this look like - 'Ouch'. He said if it got warm enough on a long road trip (which I was planning on this weekend) it would've locked up on me.

They quoted 4 hours labor for the job. Labor total is $340. They'll call me tomorrow with a price on the diff. They'll also let me supply my own part if I can get it cheaper. Bavarian Recycling has it for $480 shipped but 7-10 days. I have a rental in the mean time.

Basically the tech explained that since it had a leak before I even did any service to it, putting in the lower viscosity fluid allowed it to fly out of the leak @ the front seal even easier. That in turn left me running on about 20% of the fluid required which burned up the diff. When I pulled into the lot, the front seal was leaking bad.

Apparently the diff is an LSD type in the Xdrive models.

For the Xdrive models they spec Castrol XAF-XJ (75w-140) which retails for roughly $20/half litre. But they said Redline or Royal Purple 75w-140 with LSD additives will do the trick.

The dealer I purchased it from would not 'goodwill' it and still wanted me to tow it down there (2hrs away) and charge me $125 to diagnose. B@$t@rds.

So in the end - self inflicted but I basically exacerbated an existing problem. All in all - glad it happened now than on a long road trip with the wife and kids in the car.

Those rubber guibo joints wouldn't cause a grinding noise like that. Worst you get when those wear is slack in the driveline causing rough shifts.

He would need to have all 4 wheels off the ground, otherwise the front wheels would pull the rears off of the stands...

But at least it is in good hands and at a shop that will work with you. Hmmm. I forgot the x-drive X5s had LSDs... I might do an upgrade if I come across the right deals!

I think this is something we need to make members of the forum aware of. We should probably get the fluid maintenance section updated with a note or something. I'm not sure how to go about doing that....

salamat po ;)

You're welcome!

Warning: Temporary thread-jack ... hope you can make it out to the June 6th Connecticut meet! The more the merrier! :thumbup:

I will pencil it... errr... add it to my hotmail calendar... in.

No X5 has been supplied with LSD. because it will not work with DSC or ASC. DSC controls the spinning and works as an LSD. guibo rubber joints can certainly make a sound like that.

Thanks for your input Olemaxi. I appreciate your time.

I took a picture of the diff housing and caught a picture of the guibo and it looks pretty good. I've seen bad ones and this one looked pretty good. I updated my original post on page 1 with the pics.

Thanks to you guys who helped diagnose the problem. This kind of stuff is invaluable.

So for a resolution, it was the rear differential. I was able to locate a used one with 18,000 miles for $400! They delivered it next day for free and the shop charged $340 for installation and to fill the front and rear diffs with the original BMW fluid [Castrol XAF-XJ].

I got it back yesterday and drove it around and heard no noises whatsoever but only to find that the right rear output seal was leaking after a short drive around town. Took it back today and they are replacing the seal on that side. Will get it back before the end of the day.