w124 differential weepy seals, pix, opinions? - PeachParts Mercedes-Benz Forum

scottmcphee · #1 09-11-2011, 07:36 PM

I'm chasing down what feels like a developing "lumpiness" in the ride. Pretty sure it's coming from the rear end. I am fussy about front end vibrations and have worked them all out this summer, with many parts. Nothing funny is transmitting through the steering wheel. This vibration is felt in the butt.

It seems to be road speed related and proportional to wheel speed, not drive shaft or engine RPM. Shifting into 'N' at speed makes no change to the feeling, which I'll call a "judder". Feel it most 30-45 mph / 50-80 kmh, car and trunk are empty, just fuel and driver. The lumpiness is worst on first run of the day going up a long sloping road. It seems to get better in the drive as everything warms up, or maybe I just start to get more used to it. It's more like a tire out-of-round feeling than a tire out-of-balance shimmy. Michelins all around are all new this season. The feeling has been coming on over this same set of wheels so I don't think it's and out-of-round condition.

I know people may suggest: engine mounts, transmission mount, drive shaft center bearing and mount... all replaced within last 2 years and checked and still in sound condition. Both flex disks... inspected and in solid condition. I'm pretty sure this one is more ground/wheel speed related, not drive line.

Much has gone into front and rear suspension, but I haven't touched the differential or rear axles since getting the car (3 years for me). The ride height all around seems good.

I started by checking and replacing the diff oil, today. Took a few pictures in the area, and asking for opinions on this judder, from the conditions of what you see...

Photos in order they appear: 1) shot directly up at the differential front seal area. Yup, that front seal is wet. 2) driver's side axle. The rubber boot is not so wet but the block where it attaches to the diff is crusty... 3) passenger side axle. 4) Left rear differential mount. Are these shot? 5) Right rear differential mount.

The diff oil drained out was about 950ml, probably all that was left of the original oil. I put about 1100ml of 80w90 gear oil back in, as per spec. I was hoping low or poor oil was causing the problem, but no, everything was wet and the old oil looked good - dark bronze but no metal flakes. I poked a snake camera in the fill and drain holes to look at condition of gear teeth, they appear new.

scottmcphee · #2 09-11-2011, 08:06 PM

Things I have replaced within last 2 years in the rear:
- shocks, Bilstein comfort (nice ride!)
- suspension links, 4 per side (typical control issues and tire wear)
- outer lower wheel carrier bushings (were groaning)

The rear subframe bushings to chassis still appear to have life in them, not totally squashed.

jobadiah · #3 09-11-2011, 10:03 PM

Similar symptoms on the rear of the '95 e300, sound was a constant "whump", faster with road speed, putting in neutral no difference. Jacked the car and tried wiggling to see if bearing was failing, seemed to be nice and tight, was about to give up cause everything looked great, when i spun the back wheels (individually) as fast as i could manually spin them in neutral, my driver rear wheel made a slight roaring sound. So I replaced that bearing and that was it! It's worth a looksee, good luck and tke care!

sixto · #4 09-12-2011, 12:35 AM

The diff mounts look okay. The usual sign of wear is the left bolt sitting low in the hole.

Sixto
87 300D

BodhiBenz1987 · #5 09-12-2011, 01:12 AM

I'll second the wheel bearing idea. I had a very annoying vibration that took me forever to get rid of ... I replaced all the driveshaft stuff, front WB, rotors and tires. The tires helped, but still noticed a vague vibration at 55 mph+. THEN I rebuilt my rear end, because it was wandering, listing to the right, clunking and just looked horrid ... as it happened, the vibration went away after that job, too. In my case, I think the differential bushings had something to do with it ... but yours don't look nearly as bad as mine. One bolt was touching the subframe, the other close. The other thing I found was that one rear hub was really wobbly ... I don't know why I couldn't detect this in the past when I jacked it up and wiggeld the tire. I noticed it as I was taking the wheel carrier off the subframe. I suspect that caused some of the vibration, and new wheel bearings on each side made a big difference. I can't say for sure that was the cause, because I replaced quite a lot at once, but it's an idea. If you haven't already, I would also double check the play on your front bearings.
I wouldn't immediately be worried about the gunk on your diff, assuming it's original and hasn't been thoroughly cleaned at any point. Maybe you could give it a good Gunk cleaning and track leakage from a clean start.

t walgamuth · #6 09-12-2011, 06:06 AM

The pinion looks to be weeping a bit. Nothing to worry about yet probably.

Did you check your half shafts for play? In my experience they are likely to cause trouble before the bearings.

Diesel911 · #7 09-12-2011, 01:56 PM

Degrease the Differential.
If you have not done it check the Lube level in the Differential.

balge · #8 09-12-2011, 02:21 PM

All that rubber looks fine, are the diff bushes alignrd properly? Have'ny got the docs handy. Have you checked and cleaned the top vent? If that blocks up you can get oil blowing out when it over-pressures.
Doesn't look to oily to me, bearing in mind that could be 20 years of accumulation!
Is the 'lumpiness' a regular vibration? Could it be engine-related, bearing in mind you say it's worst when cold?

scottmcphee · #9 09-12-2011, 03:17 PM

All the weep and crud is probably life long accumulation. PO was pretty good about recording maintenance, don't recall seeing diff fluid change. That's one of the reasons why I was under there.. For the amount I drained out, there hasn't been too much leakage.

Didn't know about vent on top of the diff, I'll try to clean that while under cleaning up the crud on everything so I can track any leaks better.

I have done the front but not the rear wheel bearing job, so I will check wheels for any side/side and up/down play on their carriers. There is no roaring, groaning, whining, squealing or grinding sounds from rear bearings when traveling straight or doing side/side turns.

Is it rotational slop or deflection off center axis that I'm looking for on half shafts? (Maybe both kinds of wear come as a package?).

How much slop is OK for rear half shafts? Is there a test like putting it in park and rolling the car back and forth to measure the distance you can rock the car? Or jacking up one rear wheel with other on ground and with car in neutral or park, how much rotational angle the wheel can be moved through?

Thanks

t walgamuth · #10 09-12-2011, 09:01 PM

PUt the car in a position where the axles are not stressed, such as in neutral not park with the park brake set. Grab the half shaft and see how it moves. In and out toward the diff is ok. any up and down play is bad. it denotes wear in the cv. YOu can drive it for a bit that way but it will only get worse until it is changed.

My son came in from a three hour trip one time in a 280e I had and said there was a vibration in the car that got quieter when he drove fast. (He was going about 90). I said hmmmmm. I went out and started the car and started to back it up. Crunch, thump crunch. the cv's were past gone.