Low/high speed grinding sound
 

Hello fellow enthusiast, please bare with me, I will be including lots of details for the issue I am experiencing;

About a week ago, I noticed a fairly large puddle of oil, at the time, I thought it was engine oil, it did not have the fuel smell of used engine oil, but I had done an oil change recently so that made sense, anyway, I checked the engine oil and it was at the mark I left at when I changed the oil, weird, okay.

So fast forward to 3 days ago, my wife is on her way to work when she calls in a panic that there is this loud grinding noise, I drive there, investigate the car and notice that the front driver side axle is about 1/2 inch out of the diff... so, in the parking lot I lift the car and tried to snap it back in, that didn't work, I then pulled fuse #46 and went for a slow drive, noise was gone. I drove it back home, removed the axle, apart from diff fluid being everywhere, I did not see any issues with the axle, circlip was good, splines were good, nothing wrong with it, even the CV joints were good. I put the axle back, seated it back into the diff (really complicated when you're working in -32 degree weather), refilled the diff with 75w90 oil. Put fuse #46 back and the sound was still there. Remove fuse 46 sound is gone again.

Details about the sound, it is really loud when driving low speeds, I can feel the steering wheel shake at about 2mph. It seems to be coming from the front/mid of the car. I remove fuse 46, sound is gone, this tells me its not trans, brakes or wheel bearings, its either transfer case, front drive shaft, diff or axles(?) It sounds like straight cut gears in a race transmission mixed with metallic grinding. I have not driven the car higher than about 5-10 mph with the grinding sound because I don't want to cause more damage. When my wife was driving she was on the highway at 60mph and I could hear the sound over the phone. It is loudest at lower speeds and steering does not influence it.

Details about the car; 2006 X5 4.4l canada spec car, got the car a couple of months ago, no lights on the dash (anymore), changed a lot of engine related things, VANOS solenoid seals, oil, filter, fuel pump and filter, spark plugs, expansion tank, water pump, water transfer pipe to water pump the short rubber/metal one (this actually caused a coolant leak which I need to investigate and fix too, it's not the usual n62 transfer pipe as that was fixed by previous owners mech), thermostat, all the coolant temp sensors (they were aftermarket, temp gauge was inaccurate and causing no start issues, I used VNO).

There are no codes to speak of until I remove fuse 46, then the dash lights up with traction control, ABS warnings.
From my understanding, I have been reading tons about this, the facelift model does not suffer the same front driveshaft issue as the post-face lift model, it could still be the case? How would I troubleshoot this?
I checked both front axles, they seem to be fine, wheel bearings would not be the issue otherwise the sound would remain after pull fuse 46, it's not brakes for the same reason.
So (to me) the only culprits would be the t-case, front diff, front drive shaft and maybe the axles, maybe axles make the sound only under load(?)

How would I go about troubleshooting this quickly/easily, it's bloody cold here at the moment and I need to fix this outside in the elements.

Side note, I have no cooking clue how the front driver axle popped out the diff... I did notice that when I removed the 12 point 36mm nut, the splines were free of the wheel hub and I did not need a puller or anything to remove the axle hub side... So someone was in there recently... :banghead:

Any advice is welcome, I am fairly proficient with cars, I rebuilt an e46 ground up.

Thats a strange one for sure. Sounds like the PO may have had the same problem and had to re-seat the axle as well. Could the axle joint(s) have failed in some way that is hard to duplicate with it out?

That's probably wishful thinking, so my guess would be a failing front diff, or I wonder if it is possible for a failing tcase or front driveshaft splines to cause things to vibrate badly enough to pop the axle out of the diff.

I'd start with the easy and move to the difficult as you rule stuff out. I seem to recall your car will drive without the front driveshaft? If so maybe pull the front driveshaft first, check the splines and if they (and the Tcase splines) look good then take it for a drive in 2 WD mode. No vibration would narrow it down while vibration remaining would certainly point to maybe the axle or most likely the diff.

I'm afraid none of it's easy, especially with your temps, but the front diff in my view would be the most challenging by far. Motor has to come up a few inches and the subframe needs to come down a few inches. It also weighs a ton so getting it back in laying on your back is fun. I'm not sure there is a rebuild kit for it either, but ebay pieces aren't too expensive. Notwithstanding the cold, it sounds like you could swap the diff out in a hellish day or two if you have a way to lift the motor and enough jacks/jackstands. PM me if it comes to this as I just had mine out of my 2002 E53 4.4.

When I pull fuse #46 to get it to rwd or 2wd, the sound and vibrations are gone, to pull the front drive shaft I need to remove the t-case since its the electric t-case (xdrive) with the shorter drive shaft, I did read some information about removing the guibo then the shaft, but that was for the pre-facelift models, currently I couldn't do that until summer anyways due to -30 degree weather.
Good point on the vibration causing the axle to pop out! It entirely could have been, we have owned the car for 6 -7 months and the sound/vibration only started 3 days ago. I do believe the axle popped out before the sound started though, I dont daily drive it so I couldn't say for sure.

From what you said though, it may seem that it is the t-case, it's a good point that driving it in rwd mode and the sound stops, which it does, technically the axles are still spinning the diff and crown ring, just not the pinion and drive shaft, therefore the only non moving part would be the t-case, the front driveshaft and or diff pinion, right?

Without removing the t-case/drive shaft what would be a good way to diagnose further?

Thank you for your input!

Ok, so it sounds like you drove it in 2wd mode after you pulled the fuse. Forgive my post-facelift/non M62 ignorance...and the fact that I should have read your original post more closely! I know post face-lift T-case's are different (limited slip?) and I think the front diff is different in some respect. I'm not sure if they are different internally, but I do see reference to "cast iron" front diffs on older E53 x5s.

I'd say that whatever stops rotating/operating (in the Tcase?) when you pull that fuse is a prime candidate to look at, and the splines too.

If it does look overwhelmingly like the driveshaft splines, I'd just cut your old driveshaft at the spline weld (Tcase side) and work it out. Then get the Everbuilt lengthened front driveshaft spline kit off of Amazon. Assuming the driveshaft and tcase side splines are identical to the pre-facelift models, I can tell you that you'll be able to get significantly more splines in the tcase without pulling it.

The Tcase end is quite deep, but the OEM spline and shaft design don't allow for the shaft to sink very deep into the Tcase for removal. The Everbuilt fix can be set where you want it and will go much deeper into the transfer case to allow for installation. The new splines are longer, as is the part that fits into the driveshaft, which allows you to cut the driveshaft back a bit further, giving you additional play to install it. The dinky dust cover may sit a bit further away from the tcase, but you can trial and error it before cutting too much, or find a different dust cover solution.

I was able to get an extra roughly .5" of splines into the case without removing it, and could have done more but the fit of the splines into the shaft was very tight and I gave up trying to work it back out after overshooting a bit. I had 20 years of splines not failing on the old shaft (although they were looking a bit rough in spots, so I figured an extra .5" on the new splines would way outlast the rest of the car at this point.

This is all assuming you luck out and it is the splines on the shaft. If your AC condensate line drips on your tcase/driveshaft I'd seriously suspect the splines.

Have you looked at the right axle? I wonder if it could be out of whack somehow enough to cause the vibrations and the left axle to pop out? A long shot but maybe worth a look.

Oh interesting, I see the spline kit, that’s a good thing! Thanks for that!

As for the passenger side axle, it seems to be fine, Apart from taking a look at it, I didn’t investigate further, I will take a look once the snow stops.

Regarding the t-case, I believe that the n62 has a clutch pack instead of the planetary gears like the m62 has, it has a little motor on the side of the t-case that actuates a worm gear to engage or disengage the clutches, either turning it to awd or rwd, so by pulling the fuse you disable that motor, along with traction control and abs (which is an issue in snow, that’s why I don’t just leave it rwd) there really isn’t enough info on the t-case insides for the facelift models.

As for the post facelift, I think it’s just a mechanical ratio split using planetary gears? I’m not sure.

The thing that concerns me the most, is that the spline issue is not a common at all on the n62 facelift, where it is on m62… I hope it’s as easy as welding on a longer spline gear.

But that pretty much answers my question and what to look at first, I reckon, check the driveshaft and passenger side axle, maybe take out the driveshaft and investigate.

I’ll update the thread as soon as I can get the car in the air. Thanks! I appreciate the advice!

Just a theory, but if someone has replaced the axle and had trouble with the snap ring and grove, something could be damaged allowing the axle to pop out easily and then the transfer case gets abused trying to compensate for the torque difference. You would think there would be no warning light on the dash though, unless maybe the previous owner disabled or covered it

Low/high speed grinding sound
 

I checked the splines and canal (?) where the snap ring snaps into, it doesn’t seem worn or damaged (thankfully!!!!)

Honestly though, I had a real rough time placing the axle into the diff, to the point where I took a rubber mallet handle, rested it on the inner boot wall and hit it with a hammer 6 times to get it in there. Before doing this I of course removed the snap ring and made sure the splines line up and the slid in perfectly. Somehow, the boot is not damaged. I am thinking that the extreme cold shrunk everything so it was just tight.
Oh and, the axle was definitely changed, it’s an aftermarket unit.

I used inpa and bmw scanner, no codes in the dme, tcu or abs modules for any kind of drive train issues. I actually scanned it with inpa before buying it to make sure there was no vin mismatches or serious engine/drivetrain issues.

Having just been through axle hell and back, three times, I learned a technique on this form that seemed to help a lot. Someone posted that if you have trouble getting the clip to seat, pull it out, turn 90ish deg and try again, and again, until it pops in more easily. This worked like a champ for me. Front right wouldn't go in so I pulled it back out, turned it what I felt was 90 deg and it went in with very little force. I wish I would have read this before wrestling with the first two axles. Your milage may vary of course.

I wish I had read this before yesterday [emoji1787] damn that would have helped, I’ll probably be dealing with this soon enough, thanks for the tip! Very much appreciated.

Well, I found the culprit, I took the front drive shaft out (1” modded splines were installed by PO) the drive shaft was not the issue.

I wiggled the input flange on the front diff and it has about 1cm of movement up/down/left/right and about 5mm of play front to back. So the bearing there is shot, the grinding sound is probably the balls from the bearing tearing the innards of the diff to shreds.

I was thinking of getting just a new bearing but I doubt the inside gears are any good. So a replacement diff is needed.

Im going to be checking junkyards and partouts in the area for a replacement diff. Drive shaft is out and the diff is still making the grinding sound, so driving the car is off the table, since all the fluid leaked out there’s a risk that the other bearings seize.

I will be updating the thread as I go, I’m definitely interested in what the inside of the diff looks like.

Thanks all for the tips and strategies!