Low/high speed grinding sound

[80stech]

There should have been a lot of whining from the diff long before it got that bad. Rebuilding the diff is not a DIY job and the gears are likely to be noisy after even if they don't look damaged. I don't think it's all that common for the diff to go out so there should be no problem getting one from a wrecker.

[Aidzer0]

Originally Posted by 80stech

There should have been a lot of whining from the diff long before it got that bad. Rebuilding the diff is not a DIY job and the gears are likely to be noisy after even if they don't look damaged. I don't think it's all that common for the diff to go out so there should be no problem getting one from a wrecker.

There wasn’t whining, I did notice “slightly worn wheel bearing” sound coming from the front when we bought the car, I was waiting for summer to replace the wheel bearings, I guess it wasn’t the wheel bearings.

I’m assuming it’s been a cascade of issues, the flange bearing vibrating popped the axle out, which introduced the diff being drained of all fluid which made the flange bearing shatter due to overheating, and now I need a new diff. That’s what I assume happened.

We bought the x5 with the wheel bearing issue which turned out to be the diff, it wasn’t that bad sounding, it was noticeable but not imminent failure bad. So I figured that job could wait until I did everything around the engine was done. That’s before knowing it was the diff and not the wheel bearings.

[Henn28]

Well that sucks Aidzer, but at least you know now. And as long as the driveshaft is out you can do the splines if they look suspect, and the giubo. There is also a very good thread here about the driveshaft/giubo spacer route guys take to resolve the spline issue. Since you’ll have the motor up off the mounts, I’d pop new engine mounts in too if they haven’t been done.

The Bentley manual diff replacement instructions are pretty good, except you don’t necessarily need to remove the left engine mount, if you aren’t going to replace it. The top aft bolt on the diff is the long one and won’t come out because the subframe/mount is in the way. Stupid design. The other three are much shorter and don’t have clearance issues. Regardless, you can work the diff out and then the new one back in with that long bolt in the diff, or if you get the motor high enough (several inches) you can at least get the bolt all the way out of the diff with the space made between the diff and the top of the mount. You can also loosen all 4 bolts, although some are easier to access than others. Extensions, wobble heads and universal joints will be needed in various combinations.

As far as getting the diff in and out, it’s heavy and needs to go up into its “area” head-first and towards the back of the oil plan/subframe area, then rotate 90 deg or so, then move forward so you can get two bolts started to hold it in. It’s at least 45 or 50 lbs so I got it started upwards with a floor jack, but the rest was bench pressing. All while trying not to damage the outside seal, or the inner o ring seal that is supposed to be protected by a flimsy metal sliding ring (presumably slides back to expose the o ring as you torque the diff into the oil pan). The metal ring kept on popping off as I wrestled the diff into place. No leaks though so it’s tougher than it looks I guess.

An engine hoist would be best for lifting the motor a little bit at a time, and two floor jacks on either side will allow you to drop the sub-frame easily onto jack stands. I’d shoot initially for about 2 or 3 inches down on the subframe, and about the same on the motor, but in increments. The subframe is held up by six torx head bolts and has a guide pin on the unibody to help get it back up into place easily. You may need a little trial and error as you find the right amount of space between the motor and the subframe to maneuver the diff out.

Finally, one of the guys here recommended Amsoil severe gear oil in the collapsible bag. The filler hole is a bit hard to get to, so the collapsible bag worked like a champ for me. Three bags were more than enough for the front and rear diffs. I think each bag is 1 quart, delivered to your door. The plugs can be a pain, and mine did come out finally, but I’d recommend ordering new ones. They take a giant hex head for some bizarre reason. Another tool that only has one use…thanks BMW. The good news is now I have a whole set of mostly useless giant hex head drivers.

[Aidzer0]

Originally Posted by Henn28

Well that sucks Aidzer, but at least you know now. And as long as the driveshaft is out you can do the splines if they look suspect and the giubo. There is also a very good thread here about the driveshaft/giubo spacer route guys take to resolve the spline issue. Since you’ll have the motor up off the mounts, I’d pop new engine mounts in too.

The Bentley manual diff replacement instructions are pretty good, except you don’t necessarily need to remove the left engine mount, if you aren’t going to replace it. The top aft bolt on the diff is the long one and won’t come out because the subframe/mount is in the way. Stupid design. The other three are much shorter and don’t have clearance issues. Regardless, you can work the diff out and then back in with that bolt still in the diff, or if you get the motor high enough (several inches) you can at least get the bolt all the way out of the diff with the space made between the diff and the mount.

As far as getting the diff in and out, it’s heavy and needs to go up into its “area” head-first and towards the back of the oil plan/subframe area, then rotate 90 deg or so, then move forward so you can get two bolts started to hold it in. It’s at least 45 or 50 lbs so I got it started upwards with a floor jack, but the rest was bench pressing. All while trying not to damage the outside seal, or the inner o ring seal that is supposed to be protected by a flimsy metal sliding ring (presumably slides back to expose the o ring as you torque the diff into the oil pan). The metal ring kept on popping off as I wrestled the diff into place. No leaks though so it’s tougher than it looks I guess.

An engine hoist would be best for lifting the motor and two floor jacks on either side will allow you to drop the sub-frame easily onto jack stands. You may need a little trial and error as you find the right amount of space between the motor and the subframe to maneuver the diff out.

Finally, one of the guys here recommended Amsoil severe gear oil in the collapsible bag. The filler hole is a bit hard to get to, so the collapsible bag worked like a champ for me. Three bags were more than enough for the front and rear diffs. I think each bag is 1 quart, delivered to your door. The plugs can be a pain, and mine did come out finally, but I’d recommend ordering new ones. They take a giant hex head for some bizarre reason. Another tool that only has one use…thanks BMW.

Amazing information!! Thank you so much!

Regarding the driveshaft, I had one hell of a time getting it out because it is the 1” extended spline shaft, the job was done by PO. I actually took an angle grinder to the input flange on the diff since that’s going to get swapped out, i literally took off about 2 mm off of the diff flange and the drive shaft popped out without the transfer case needing to come off.

Good idea on the engine mounts!! I’ll definitely do that, I’m also thinking since the n62 motor has that stupid alternator bracket seal/gasket issue, while I’m in there I might as well change that.

Regarding the diff oil, I just turned the drivers side wheel and I have access to the hex fill plug, I did notice that it has a green o-ring, so I’ll see if I can get those too. I’ll also change out the rear diff and transfer case fluid while I’m there.

So the shopping list for me so far is;
Alternator gasket
Both axels (just in case)
Diff 4:10 ratio
Both sides output shaft seals
Engine mounts
75W90 gear oil (I have a transfer pump if needed)
Hex fill/drain bolts or o-rings for front and rear diffs

Would there be anything else that I need while I’m there? Thanks!!

[Henn28]

Originally Posted by Aidzer0

Amazing information!! Thank you so much!

Regarding the driveshaft, I had one hell of a time getting it out because it is the 1” extended spline shaft, the job was done by PO. I actually took an angle grinder to the input flange on the diff since that’s going to get swapped out, i literally took off about 2 mm off of the diff flange and the drive shaft popped out without the transfer case needing to come off.

Good idea on the engine mounts!! I’ll definitely do that, I’m also thinking since the n62 motor has that stupid alternator bracket seal/gasket issue, while I’m in there I might as well change that.

Regarding the diff oil, I just turned the drivers side wheel and I have access to the hex fill plug, I did notice that it has a green o-ring, so I’ll see if I can get those too. I’ll also change out the rear diff and transfer case fluid while I’m there.

So the shopping list for me so far is;
Alternator gasket
Both axels (just in case)
Diff 4:10 ratio
Both sides output shaft seals
Engine mounts
75W90 gear oil (I have a transfer pump if needed)
Hex fill/drain bolts or o-rings for front and rear diffs

Would there be anything else that I need while I’m there? Thanks!!

I keep forgetting that you have an N62. The Bentley procedures are the same, but take it all with a grain of salt!

My plugs didn't have o-rings, so I ordered new plugs. I wasn't sure if I could just throw a generic crush washer on them. I read that there are different torques for o ring and non-o ring plugs, and my new ones came with o rings.

The alternator bracket is a very good idea, since that causes the N62 guys no shortage of heart ache it seems. Having the stiffener plate off, the diff out and the sub frame down a bit opens up a lot of inspection space, so in addition to the oil pipe o-rings, I'd do all your power steering crush washers, inspect all the heater hoses that you can see (assuming any are routed into the basement of the engine bay like one is on the M62 cars), and if you pull the fan and shroud to make more room to get the motor up without damaging your radiator by mistake, I'd perhaps replace any lower coolant hoses since they are cheap and can be tough to get off without the extra space.

As far as the splines go, I don't get the sense they are a problem with the N62 cars, and yours are newer anyway. So if they look good then I'd leave well enough alone. Maybe some N62 guys can weigh in. Having the diff off would certainly make installing longer splines "easier" though.

[Aidzer0]

Originally Posted by Henn28

I keep forgetting that you have an N62. The Bentley procedures are the same, but take it all with a grain of salt!

My plugs didn't have o-rings, so I ordered new plugs. I wasn't sure if I could just throw a generic crush washer on them. I read that there are different torques for o ring and non-o ring plugs, and my new ones came with o rings.

The alternator bracket is a very good idea, since that causes the N62 guys no shortage of heart ache it seems. Having the stiffener plate off, the diff out and the sub frame down a bit opens up a lot of inspection space, so in addition to the oil pipe o-rings, I'd do all your power steering crush washers, inspect all the heater hoses that you can see (assuming any are routed into the basement of the engine bay like one is on the M62 cars), and if you pull the fan and shroud to make more room to get the motor up without damaging your radiator by mistake, I'd perhaps replace any lower coolant hoses since they are cheap and can be tough to get off without the extra space.

As far as the splines go, I don't get the sense they are a problem with the N62 cars, and yours are newer anyway. So if they look good then I'd leave well enough alone. Maybe some N62 guys can weigh in. Having the diff off would certainly make installing longer splines "easier" though.

All good ideas, I got quite the shopping list now! Thank you very much!

The aftermarket extended splines were already welded onto the drive shaft.

While I was down there on my initial troubleshooting I checked for leaking coolant pipes and nothing seemed to be leaking, I do however plan to do a full power steering refresh which will be for another day. I am using someone else’s workshop so I cannot be there for too long unfortunately.

I do have a coolant leak on the passenger side by the rad, it seems to be seeping through a 3 T junction of small hoses. Not sure what part is leaking though, I’ll be replacing those hoses and the T junction once the diff is fixed. I don’t need extra room for that, thankfully.

[Aidzer0]

A quick update, I got a replacement diff from a salvage yard, I got most of the parts that I need, the dealership did not have the profile gasket (P/N: 31507527999) that goes between the diff and oil pan, they only had the o-ring (P/N: 31511213527).

I also did not get motor mounts due to extremely high pricing at the dealer and also availability where I live, the motor mounts were replaced by the PO anyways so its not detrimental to the job.

I will need to wait 5 days for them to get the profile gasket in, which is a bit of a dissapointment, I was hoping to have the diff replaced this weekend. But alas, I will have to wait for next weekend. I am really looking forward to pulling the diff and cracking it open too.

[Henn28]

Nice work! I had to shop around for motor mounts as OEM were crazy money and the better brands were out of stock at a lot of places.

I'll be interested to hear what you find inside that diff, pics please. Mine weeps the slightest bit of oil from the lower bolts holding the halves together, but I couldn't torque them at all. I did a half hearted look for gaskets and any other internals for the diff and couldn't find anything on the internet either. I guess if it ever comes to it and I need to address any heavy leaking I'll need to make a gasket.

One more note, I had a tough time pulling the breather tube out of the top of the diff. The flexible rubber bit that went into the diff was nowhere near flexible any longer and it shattered. I ended up having to make a new connecting piece out of larger vacuum tubing. A lot more wd40 and patience may have helped.

[Aidzer0]

Originally Posted by Henn28

Nice work! I had to shop around for motor mounts as OEM were crazy money and the better brands were out of stock at a lot of places.

I'll be interested to hear what you find inside that diff, pics please. Mine weeps the slightest bit of oil from the lower bolts holding the halves together, but I couldn't torque them at all. I did a half hearted look for gaskets and any other internals for the diff and couldn't find anything on the internet either. I guess if it ever comes to it and I need to address any heavy leaking I'll need to make a gasket.

One more note, I had a tough time pulling the breather tube out of the top of the diff. The flexible rubber bit that went into the diff was nowhere near flexible any longer and it shattered. I ended up having to make a new connecting piece out of larger vacuum tubing. A lot more wd40 and patience may have helped.

Noted! Thanks! I have tons of silicone hoses laying around so I am sure I'll find something. I replaced all the vacuum lines in the E46 and E53 with silicone so they don't perish.

I am definitely taking photos of the busted diff and I will be posting them here.

Side note; this diff is not heavier than the E46 diff or manual trans, I installed those using my chest as a jack on a crawler :P It's not fun, but doable.

[Aidzer0]

To start the adventure, three nights ago, I was on the way to the shop where I’d be replacing the diff, 3 minutes away from the shop, my front wheels seized up and I landed up in a snow ditch, had to call a tow truck to get her out and drop her off at the shop. Nothing was damaged at all.




Okay, I take it back, that diff gets really heavy when trying to manoeuvre it in there, I got the old one out, the new one was having a hard time going in the same way but I got it in, I snapped the damned subframe bolt, front one passenger side where the engine mount is, any quick fixes for that? I need to wait for summer to properly drill it out and re-tap the threads…
I was thinking of using a ratcheting strap for the time being, around the subframe and frame rail. Or Does anyone think it would be okay to drive with no support bolt right by the engine mount? (I don’t think it’s a good idea). The rest of the subframe bolts are torqued to 94ft-lbs while the car was on the ground.

I had the car running for 45 minutes and driving for about 20 minutes and all seemed to be fine, I figured that even without that subframe bolt, I want to make sure all else is good, which it was. However…

This morning I have an overheating issue, exp tank is full and there is no heat from the vents, but it is -40°F (coldest night using the x5) and I believe one of the lines got frozen or something to that effect. I will have to wait for warmer temps to make sure, what a bloody hellish nightmare.

Took the diff apart, the pinion bearing cage was the culprit. She’s done for: