Rear end whine - diff or center support bearing?

[dionphaneuf]

My 92 500E w 240k mi has a whine or 'whomping' from the rear end of the car in operation that I've tried as best I can to capture in the attached two videos during my commute this AM. The longer one is on the highway from 60-80 MPH; it's a bit hard to hear the noise but it's there if you listen for it, along w my description of when I'm on and off load. The shorter one is driving around a parking lot from stop, where the 'whirring' that comes on once I'm moving is pretty obvious. I'm having a hard time trying to decide if it's the center support bearing (first link), or the rear diff (second link). I'm going to have the car up on a lift on Thursday night; I'd like to finally install my cat back exhaust and new hangars, but I might hold off if the support bearing or some other part of the driveshaft looks iffy. The fact that it seems to be present on and off load pushes me a bit in the center support bearing direction, but the noise' frequency and the cars service history makes me think it's more likely to be diff related. It had diff fluid done at 205k mi when the PO complained about noise; a shop changed the fluid but noted metal flakes and wear in the diff. I'm going to pull the diff cover off at some point here, but might wait until the weekend - I can only keep it up on a lift for a few hours on Thursday night, which I don't think would leave me enough time to close it and for a sealant to cure altho maybe some 90 min Right Stuff would work.

HELP! Mystery chirping/squeaking noise | Troubleshooting and Diagnostics

My 500E has developed a mystery noise that two mechanics and an exhaust shop have been unable to identify (and they are getting annoyed by the fact that I'm not letting this drop). Here are the symptoms: 1) When the car is rolling, there's a noise I can best describe as the kind of high-pitch...

www.500eboard.co

Rear end whine | Transmission and Driveline

Not my favorite choice of German whines. Car has 240,000 miles. Fresh gear lube didn't seem to make a diff(erence). Should I learn to live with it or what?

www.500eboard.co

Noise at highway speed

Noise at low speed - in and around a parking lot

Will document my findings here; hoping I don't need to replace the diff as the noise is pretty annoying to me and detracts from the experience of the car. At the very least, maybe some fresh redline 75W90 will help but I'm not super optimistic so looking for some 2.82 or 2.65s...

 

[dionphaneuf]

I should add that I'm a bit skeptical it's the wheel bearings - I don't hear a 'roar' turning in either direction. I do hear a bit of 'thunk' at times on throttle application which points to something in the driveline.

 

[gsxr]

The low speed doesn't sound like the diff gears at all. Could be center carrier bearing/support (replace both if you tear into that fun job) but hard to say without isolating the location more definitely. Center bearing is sort of below the driver seat armrest.

Gear whine will change dramatically between on throttle and off throttle, and if you play with the accelerator pedal on a flat road you should be able to make it go away completely in the right conditions. If so, that is very likely the differential itself.

Rear wheel bearings tend to make a dull roaring that gets louder as speeds increase, for nor'east residents, it sounds a like like you have one snow tire mounted.

 

[szvook]

What’s up with the check engine light?

 

[dionphaneuf]

What’s up with the check engine light?

It's the EGR - fixed the vacuum hoses but didn't solve it, finally got the gasket so I can remove the actual valve to clean it.

 

[dionphaneuf]

Sounds like I need to do some more inspection and exploring when the car is on the lift. Think it’s worth taking the diff cover off?

 

[gsxr]

Sounds like I need to do some more inspection and exploring when the car is on the lift. Think it’s worth taking the diff cover off?

Nope. Have to remove the diff from the car to remove the cover, and there's nothing to see visually...

 

[dionphaneuf]

I spent some time looking at the flexplates and drive shaft when I was installing my exhaust yesterday - video w crappy cinematography below. I couldn't find anything super obvious - the rear flex plate looked older but generally okay, the front one looked brand new. I'm going to put some Redline 75W-90 in the diff to see if that changes things - the place that did the last change has done some other work on the car that later proved spotty so this will at least let me 'get back to zero' and rule one thing out. I suppose it's possible given the age/mileage it could just be the diff itself. The fact that some level of whirring appears the second the car is in motion leads me to suspect some type of moving part, whether it be a wheel bearing or something else. I know typically their noise changes w load (ie left or right turns) but I don't hear a ton of that here, so need to investigate more.

 

[r44raven]

I had a whine from the rear of my 500e - most obvious between 20 and 50 mph. The frequency increased with speed, but the pitch did not. The noise did not alter on left or right bends.

The car had done 150k + miles, and not knowing when/if the wheel bearings had ever been replaced, we set about replacing them, to find one of them completely shot. Upon replacement of the rear wheel bearings, the whine disappeared.

 

[JeffSpicoli]

@dionphaneuf did you ever find the source of the whine? I'm suffering the same issue.

 

[dionphaneuf]

I think it's the diff itself. I've not yet taken the time to dive into this one more yet though. I'd love to find a really good shop in the Bay that can diagnose this a bit better before I dive in, but it fell off my radar for a bit. Thanks for the reminder though - I'll bump it back up my list and keep you posted on what happens.

 

[dionphaneuf]

This has been driving me insane for long enough that I spent some more time digging into it. It's just so annoying and detracts from the experience of the car. I called Sun Valley Mercedes and spoke to Mark, who was generous to talk to me for 20 mins about diagnostics and DIY tips; while they dont' do diffs he had experience with them in the past. He gave the following suspects and tips with the rear of the car on jack stands

1. The Pinion bearing: Try looking for any obvious wear or play moving the driveshaft axially and radially. Could be hard to tell but the most likely culprit
2. Diff mounts: Try raising and lowering the diff with a floor jack to see how it moves
3. Axle/half shafts: With car in N but parking brake on, rotate drive shaft in both directions and see if splines in half shafts and u joints move immediately or lag/have play. Supposedly the passenger side splines wear out more quickly.
4. U Joints: Condition should be obvious from under the car, look for clicking
5. Wheel bearings: Will maybe take wheels off and inspect, but will give em a good shake when off the ground and look for obvious play
6. Center Support bearing: I'll try as best I can to get a look at this from under the car, and to move the driveshaft a bit to see what kind of shape its in. The sound seems to be coming further rear than that though.

I'll tackle this on Saturday AM hopefully and report back.

 

[gsxr]

#1: If you have a whining noise that changes as you are on/off the throttle, the differential is the most likely culprit.

#2: The diff mounts are very robust. A small amount of movement is normal. I've never seen the rear mounts wear out, even at 200-300kmi. The subframe has to be lowered to replace them.

#3: It may be difficult to check for play at the CV joints with the axles in the car, as you cannot have them level with the car jacked up. If there is play at any CV joint, that is suspicious. They should be tight. The axle shaft will move side to side easily, this is normal.

#4: The driveshaft U-joint will be inaccessible without removing the entire exhaust system. This may cause vibration but should not cause whining noises.

#5: Rear bearings usually cause a roaring noise, that may get better or worse in a long sweeping curve either right OR left. The roaring is often with zero play at the bearing, however with the axle shaft removed you can feel the bearing is rough when turned by hand, compared to a new one. If you can feel play moving the rear wheel by hand, that may indicate a bearing issue (again, this is rare, I've never found a rear bearing with detectable play).

#6: See #4 above. If you pull the exhaust, I'd just replace the support (the rubber hardens and sags with age) and bearing (they are usually worn enough to be rough & have play after 100-150kmi or so). Again, this should not cause whining noises. With 240kmi, I would strongly recommend replacing the carrier & bearing unless there is a record of it being replaced in the past.

 

[dionphaneuf]

Awesome, thanks. After a lot of driving and listening, I'm almost certain it's #1 sadly, and I'm hoping to find some play in the pinion bearing that would suggest it's the culprit rather than the gears inside the diff but I'm not super optimistic. Can the pinion bearing be R&R'd with the diff still in the car? Any other diagnostic tests you'd recommend with the car on jack stands to push me in one direction or another?

 

[gsxr]

The pinion bearing is not DIY replaceable. You either swap in a used differential (easiest & cheapest), or pull the diff out and pay a shop to rebuild it. Diff bearing failures are super rare, as you may have figured out from the lack of threads about gear whine. The diff R&R is medium DIY and takes roughly 4 hours if you have all the tools (including impact wrench) and don't encounter problems.

I think the tests you listed above covers most bases. As noted previously, diff whine almost always changes volume or pitch as you ease on/off the throttle when cruising on a flat road. If this does not happen, it may not be the diff. Rear wheel bearing noise will not change on/off the throttle, it's dependent on vehicle speed and cornering loads.

 

[Jlaa]

Rear wheel bearing noise will not change on/off the throttle, it's dependent on vehicle speed and cornering loads.

@dionphaneuf I re-listened to the highway video on post one twice this morn, and to my ears it sounds like the whirring noise is there whether you are on or off throttle?

 

[dionphaneuf]

It's present on both. Turning has no impact on it which leads me to believe it's not a wheel bearing but something in the diff. I can definitely play with the throttle to get it to go away; last week on a long downhill while coasting it was totally gone.

@gsxr does any pre 95 W140 400/420 ASR diff work, provided I swap the rear cover/other parts as needed? I looked at your doc referrenced in this thread, and these two 95 W140 S420 diffs are fairly cheap so I may buy one if it fits (partially for insurance - even if it's not the diff on my car now, it's likely not that far away from being an issue).

This one from eBay is in Sacramento so would be an easy pick up, LastVIN shows it as a Feb 95 built S420.
This one from eBay is in Dallas; no pn visible.

 

[gsxr]

For a diff swap, these are the options, assuming you want the identical or similar gear ratio.

1) Donor from another 500E
2) Early 140.04x (up to A212244 ) diff with 2.82 gears, will bolt up using the 500E rear cover
3) Early 500SL with 2.65 gears. Donor MUST be 1990-1992 USA model year (129.066) with optional ASR. Rear cover is identical to 500E. ASR sensor wires are a few inches shorter and you may need to swap in the 500E sensors. And, a speedo converter box is required for the gearing change.

All used diffs should be opened for inspection and re-sealed prior to installation, although I'd skip the pinion seal if it's bone dry.

The Sacto diff from 1995 S420 will not work. It's beyond the VIN break of A212244 and does not have the ASR sensors on the diff. S420 diffs as of A212245 relocated the sensors to the wheel hub. You need an early 400SEL/S420 diff. Same problem with the Dallas diff.

See photo below. If the donor doesn't have the 2 sensors on top as shown, it WILL NOT WORK.

 

[dionphaneuf]

Awesome, thanks so much for the help Dave - really appreciate it. I saw your post re machined ASR holes in the thread I linked to but couldn't figure out what exact holes were being referred to. I think this one should work (2.82, from a W140, ASR holes) but it looks a tad rough so I might hold out until a US based one becomes available.

 

[gsxr]

Awesome, thanks so much for the help Dave - really appreciate it. I saw your post re machined ASR holes in the thread I linked to but couldn't figure out what exact holes were being referred to. I think this one should work (2.82, from a W140, ASR holes) but it looks a tad rough so I might hold out until a US based one becomes available.

Yup, that one in Germany is correct, but I agree it looks awfully crusty. And, shipping is nuts, $800 delivered with no way to affordably return it if defective. You should be able to get one for <$300 delivered.

Try calling Nu-Way in CA and get the VIN of their 1994 S420, use LastVin.com to check for ASR code 471.

Or for a few bucks more, the 1995 S420 at M&M (stock #M707) should be correct, VIN shown is WDBGA43E3SA198790 and it has ASR, ~141kmi according to AutoCheck. You'd have to pick it up, they claim they don't ship.

 

[dionphaneuf]

So a little update...after combing thru car-part.com for these diffs periodically and not having much luck with a 92-95 W140 400SEL/S420 diff with ASR, I found one using the Hollander direct search which seems to filter better. Many of the car-part.com ones are incorrectly listed (seems ASR wasn't crazy common on S420s) or stale/sold; Hollander seems more up to date. In particular, this 93 400SEL is at a yard in Buffalo NY and could be mine for about $225 shipped, provided the diff looks clean once they remove the cover. Car has 100k mi, compared to the 240k mi on mine - so not super fresh but would likely last the rest of my cars' life. Am I better waiting for one to show up on the West Coast, from a gentler climate? My main concern is just exterior rust and overall condition, but I'd probably give it a fresh coat of paint before putting it in the car anyway. FWIW, Left Coast yards seem to be a bit pricier, with diffs usually in the $300 + range save for the ones Dave highlighted above that won't ship and thus require a round trip to SoCal that would cost me one diffs worth of gas.

 

[dionphaneuf]

Got off the phone, diff order is in, being pulled for inspection and shipping. I'm a little nervous buying a diff from a snow state car but I don't think a diff would corrode too badly. I also spent some time under the car checking items in the list I noted some time ago - the wheel bearings, half shafts, and diff pinion all felt generally fine. Couldn't see center support bearing well, but attached photos of everything else. Here's my parts list:

Center Support bearing repair kit	124 410 01 10
Bearing carrier	124-410-08-81
Boot for Center Support	202-411-04-97

Diff side seal, Seal Ring (Interior Flange), 2x	014-997-72-47
Seal Ring (Bearing Cover to Axle Housing), 2x - Not sure I'll use these	003-997-25-48
ASR O Ring, 2x (for metal-body ASR sensor in diff)	014-997-97-48

I'll need to swap over the rear cover of the 500E diff onto the 400SE one.

Above photo of the diff bushing....it's not clear to me if I acutally need to do these as they look fine but I'm tempted to do so 'while I'm in there'. @gsxr I saw you mention that you can't get these out with the subframe in the car (assume diff is out) - I thought I'd heard otherwise?

Diff Bushing	129-351-50-42
Diff bushing tool on Body, Miller 9113
Front Diff bushing - NLA?	1243509708

The flex disc was done in 2002 at 143k miles, 100k mi ago. They look fine to me so I'll leave them. The fuel filter was last done with the pumps in 2005, 75k miles ago. I'm going to grab some parts but will save that job for another day. I'm also tempted to have the boots on the half shafts re done - the shafts themselves look/feel fine and the boots are intact but it seems prudent to do now.


This is verging on a full on @Jlaa rear end rebuild project....but I think above is enough. If there's another easy 'while I'm in there' job, please let me know. Other Photos below

 

[Jlaa]

@dionphaneuf are you gonna get the front subframe mount too? You gotta get a Febi reboxed Boge piece since its NLA … but toss the Febi stop plates and use MB stop plates under a diff part number.

Gsxr helped me figure it all out and I posted all the part numbers a few months back … start here - OWNER - ArauzMotoring | Owners and Their Cars

 

[dionphaneuf]

Looking at other threads, a few things becomes apparent

• My rear subframe bushings appear quite collapsed so I'll need new ones once I can find them
• The diff bushings at the rear are a PITA to replace and different to replace than the pedestrian 6 cyl 124 ones
• The front diff mount 140-350-49-41 is also NLA. I found one on eBay for $120...spendy, not sure if needed

 

[gsxr]

I'll need to swap over the rear cover of the 500E diff onto the 400SE one.

And also swap the ASR sensors too. Wire length will probably be different, not sure if you can use the 400SE sensors or not. Check length & connector type.

Above photo of the diff bushing....it's not clear to me if I acutally need to do these as they look fine but I'm tempted to do so 'while I'm in there'. @gsxr I saw you mention that you can't get these out with the subframe in the car (assume diff is out) - I thought I'd heard otherwise?

On V8 cars, the subframe would have to be lowered to make room for the tool. You'll see if you hold the tool up there, it won't fit with the subframe in the normal position. If you change these, make sure to carefully measure the location of each bushing relative to the subframe, BEFORE REMOVING the old ones. Pull the new ones into the exact same position.

I'm also tempted to have the boots on the half shafts re done - the shafts themselves look/feel fine and the boots are intact but it seems prudent to do now.

If those are all intact with zero play (keep reading), I'd consider leaving them alone, if you are looking for somewhere to draw the line. The CV joints should be checked out of the car, on the workbench. Get them level and roughly centered (not pushed/pulled, in or out) and try to rotate them. Should be ZERO play. If there's any... probably at the inner... shell out for new axles (or good used, on a budget).

This is verging on a full on @Jlaa rear end rebuild project....but I think above is enough. If there's another easy 'while I'm in there' job, please let me know. Other Photos below

Definitely do both front & rear subframe mounts. They aren't super difficult, most of the time, but as the HOW-TO article mentions the fronts can turn into a nightmare if the old ones don't come out easily. Standard OE rears will be fine if you don't want to source the German-repop late-Sportlines, which are the only other option right now. If the lower wheel carrier support joints aren't recent, replace them too, they are cheap and have a short lifespan.

 

[Jlaa]

@dionphaneuf if you want to put in a set of the standard rears, I have a new set could use, but I would rather see you use the German sportline repops, which have substantially more mass.

 

[dreaming.haze]

@dionphaneuf - I have a few sets of the front rear sportline subframe bushing repops if you'd like a set. Let me know if you'd want some during your job.

 

[dionphaneuf]

Thanks @dreaming.haze - how do those compare to the 129-351-14-42/202-350-34-08 kit? Looks like a few are on eBay here (but shhhh, before @Jlaa snags them if they're good). I'll grab the Febi Kit from Autohaus AZ and the right hardware for that.

Do the two rear diff mount bolts/nuts need replacing as well? The bolt is 000960-012184, but the nut 913004-012008 shows NLA

 

[Jlaa]

@dionphaneuf — fyi see this for front diff mount as well.

 

[gsxr]

Thanks @dreaming.haze - how do those compare to the 129-351-14-42/202-350-34-08 kit? Looks like a few are on eBay here (but shhhh, before @Jlaa snags them if they're good). I'll grab the Febi Kit from Autohaus AZ and the right hardware for that.

Do the two rear diff mount bolts/nuts need replacing as well? The bolt is 000960-012184, but the nut 913004-012008 shows NLA

The rear diff hardware can almost always be re-used. A new locking nut would be nice. The dealer may show a proper supercession. RevParts online has limited supercession data, sometimes wrong, sometimes missing, etc.

Let us know what you receive when buying the Febi front mount kit, if it's still the NOS OEM Boge, or newer stuff.

 

[dreaming.haze]

Thanks @dreaming.haze - how do those compare to the 129-351-14-42/202-350-34-08 kit? Looks like a few are on eBay here (but shhhh, before @Jlaa snags them if they're good). I'll grab the Febi Kit from Autohaus AZ and the right hardware for that.

Do the two rear diff mount bolts/nuts need replacing as well? The bolt is 000960-012184, but the nut 913004-012008 shows NLA

@dionphaneuf , misspoke initially - I have multiple rear sets that I ordered from the ebay from the same company you linked. They came with the semi-correct hardware as well, so bushings + spacer/washer (not used on W124) + bolt. Of a direct comparison, they seem to have the correct weight and feel to them (pass the harbor freight smell test). I haven't installed these yet on my car, but have plans to over this winter.

For the noted front kits, I bought mine from FCPeuro and received the OEM Boge bushings within the kit.

 

[gsxr]

FYI, the small round spacer/washer included with the hardware kit is not used on the 124. I believe that is used on other chassis. Do not use the spacer/washer when installing the CARUS bushings on the 124! Only the bolt and wide stop plate are required.

 

[dionphaneuf]

FYI, the small round spacer/washer included with the hardware kit is not used on the 124. I believe that is used on other chassis. Do not use the spacer/washer when installing the CARUS bushings on the 124! Only the bolt and wide stop plate are required.

Right - my understanding was that the hardware included in both the Febi kit from FCP and the eBay Rear kit was wrong for the w124, was planning on ordering the Hardware as listed in this post 32 on the subframe how to (here). Also, called Naperville and no new/superceeded PN is available for the Rear diff HW, so ordering without it.

@dreaming.haze - got it, I'll grab them from the eBay seller unless you're willing to part with a set to keep it in the US.

 

[dionphaneuf]

FYI...Naperville told me that 124-410-08-81 is NLA and can't be found at major resellers online. Same with 129-351-18-42 (available at FCP Euro) and 914125 012238

 

[dionphaneuf]

Did....someone just buy the copy of 124-410-08-81 on eBay I was about to buy last night after posting this?

 

[gsxr]

It wasn't me! I'm not finding any others... aaaargh...

 

[dionphaneuf]

The Classic Center had one in their parts wearhouse so I grabbed that. Fingers crossed its 'real' and shows up next week, reading more threads on this it seems most likely that and the diff are the sources of my knock on throttle application and the whine while driving, respectively.

 

[IslandMon]

Did....someone just buy the copy of 124-410-08-81 on eBay I was about to buy last night after posting this?

I almost posted to warn you that someone might do that!!

 

[dionphaneuf]

The diff bushings (129-351-18-42) and all related pns are all also now NLA.

 

[gsxr]

The diff bushings (129-351-18-42) and all related pns are all also now NLA.

Nuts. At least there are aftermarket versions of these.

 

[dreaming.haze]

Drat. I'd be curious if their -64 postfix (shift in supplier from memory) is also NLA. Rubber Bushing 129351184264 | MB OEM Parts

If you want to spend MSRP, looks like a supplier on eBay has the old PN: New Genuine Mercedes-Benz Mount,Axle Housing,Vlrub 1293511842 OEM | eBay

 

[gsxr]

FWIW... I got some of the 129-351-18-42-64 in late 2020, and they appeared to be normal / made-in-Germany items. At the time, they were ~$53/ea MSRP. I had no idea these went NLA in the past 18 months.

 

[dionphaneuf]

The 64 is also NLA per classic center. Thanks for the eBay link, got the OEM ones. Note that FCP showed em in stock only to later cancel that part of the order.

 

[Jlaa]

According to this website,
reproductions made in Germany of 129-351-18-42 are available….. perhaps much like how German reproductions of the aft rear subframe mounts are also available.

It was @dreaming.haze and @speedy300dturbo who found the ebay source of German repros for the aft rear subframe mounts …. They might also know where to find the source of 18-42s

FWIW... I got some of the 129-351-18-42-64 in late 2020, and they appeared to be normal / made-in-Germany items. At the time, they were ~$53/ea MSRP. I had no idea these went NLA in the past 18 months.

So much frustration! Me too - I bought a set on Nov 25 in 2020 as well from Ed Hicks…..

 

[Jlaa]

BTW are we sure that 129-351-18-42-64 is no longer available?
I checked this: meta_title and it indicates that this part is still available:



Note that the parts that I have are fresh - made in 2020.



This part also seems to be used in a number of w140s (as well as r129s) .... and w140s are newer than 124s....

 

[dionphaneuf]

When I called Classic Center about these (after my Naperville and FCP orders were both cancelled) they told me that all three versions of this PN were NLA, even the 18-42-64

 

[dionphaneuf]

I got the diff and my (unheeded) fears that a Buffalo car would be rusty were true. It sounds a bit off too tho I've never listened to one on a bench - vids are here and here. I might open it up tomorrow evening to see the insides. Wondering if it’s even worth the time for me to wire brush it and then repaint. At least I can reuse all the hardware on my diff if needed. But maybe I just cut my losses here and grab that Fontana diff when I’m next down there or find someone local to pick it up and deposit at a nearby UPS. Not sure if that particular VIN (WDBGA43E3SA198790) ever saw a real winter and rust.

 

[kegmankipp]

Damn, that looks like it was made by the Aztecs or Incas.

 

[gsxr]

Don't get too hung up on the exterior condition. If the internals are clean and appear to be in good working order, that's all you care about. Any chance there's a local media blaster that could clean it up for you, then apply POR-15 or similar stuff?

 

[dionphaneuf]

Dropped by a local shop and they weren't interested in blasting or painting so I'll probably just wire wheel it then POR15. I got the rear cover off after a bit of wrestling and managed to get the drain and fill plug loose. I'll transfer over most of the hardware from my current diff as it's a lifetime CA car or find new parts. I think the internals look good, interested to hear more. Youtube was being annoying about uploading the video from my phone and reduced the quality a lot. Some photos are below.