W210 Leak from Top of Differential?
 

Greetings. I noticed during an inspection some fluid leaking from the top of my differential. There is what looks like a fill tube or vent sticking out of the top which was caked with grime. I cleaned it off and cleaned around the bottom of it...I ask what causes a leak from this area and what should I do to fix it? I have included a photo and the tube in question is visible in the center of the frame at the top in the cutout in the steel mounting plate. Thanks all in advance for a response.

It doesn't really look like a leak from the picture. I probably wouldn't worry about it, as it is just a vent and the fill level of differential is much lower than the vent at the top.

I actually wiped the back off but you can see a wet spot at the bottom of the diff. It was leaking but if that top tube is just a vent then I won't do anything but monitor it for now. Maybe it just got plugged and some pressure built up which caused the leak...?

I have the same problem on my 97 E320. I just wiped all the grime off but I would definitely appreciate a pictorial diy to figure out how to change the fluid.

So the consensus is that this leak poses no problem?

just be sure you arent running different sizes of tires on the rear. it will boil the lube, which would prob force some out the top, and eventaully fry your bearings.

about the only known way to ruin a mb diff.

tom w

On the 97 E320, the spare tire is a full size spare so it has never been run with assymetrical tire sizes. All four tires are the same size: 215 55 16

I agree with the above assessment.

I think many of these differentials (W210) have a little bit of a weeping problem. My mechanic said "no big deal" as long as it is just a bit of weeping.

FWIW

My '96 manual says that if you do run different size tires on the rear, the traction control system gets involved. So you will probably have worries long before the differential can sustain any damage.

126 differentials
 

Just so you don't feel bad 126 differentials are known for oozing out fluid from their vents. My 24 year old 300SD has a lot of grime built up on it over the years and has never failed.

The rear differential is leaking on my vehicle. I'm concerned as to the current level of fluid inside.

The dealer is quoting me around $1500 to change the side seals that are apparantely leaking. When I asked if they could just top it up just to be safe since I do not want to spend that kind of money. I was told no it can't be done without all the extra labour. I find that hard to believe.

Can someone tell me how long a job it is to drain and refill the diff without actually changing any seals. I don't care so much about fixing the leak as I do about making sure it has fresh full fluid inside.

Do I have to take out all the bolts around the diff or is there a drain plug? Do I need any special tools?

If I have to take out all the bolts around the diff and separate the pieces, then do I need a special sealing compound before I put the two pieces back together?

Thanks in advance for any feedback.

Try this thread
 

With the car on a lift it is less than a 10 minute job to drain and replace the differential oil. If your dealer would not do that for you and just charge for the fluid and 0.2 hours time I would find another dealer. There are two plugs, both 14mm hex that need to be removed. They can be tough to get out, but if you spray them with PB Blaster and use a long breaker they come out. Take the fill plug out first so you're sure you will be able to refill it, then the drain. Some have drained them and then found they cannot get the fill plug out...then it is a tough job because you're kinda stuck without oil in there.

You can add fluid to the diff., but you are still faced witht he issue of a leaky differential.

The $1,500.00 quoted by the dealer is about right -- for a dealer that is.

Have you tried looking for a good and trustworthy indie in your area?

That may be your best solution in the long run. If the leak is serious enough (many of the W210 have "weepy" diffs., but a leak is more serious) it should be attneded to as soon as possible -- replacing a diff. can be very expensive.

Good luck.

I think there is a known problem with the differential on this car.

On my 96 W210, I've had to replace the rear differential seal 3 times since I've oned the car.
All 3 times were covered by warranty but it was still troublesome.
From my understanding, the last time they fixed it, they said they installed a newly designed seal which solved the leak and it has not leaked since then.
That might be your problem as well.

Thanks for all the feedback. I have just bought this car and seeing that the rear diff was leaking (a lot, not just weeping)worried me as I wasn't sure how much fluid would still be left inside.

The previous owner relied on his mechanic at the dealership to tell him when something was required and I guess this was of no importance! because he was surprised when I pointed it out to him. Then again the dealership told me that it was a sealed unit and that a fluid change was impossible!

Anyway, thanks to everyone's help on this forum, I've managed to confirm my suspicions that the dealership was out to lunch. I've changed the fluid myself. I had to buy a 14mm allen key. The bolts were tight as expected so I sprayed them with penetrating oil and drove the car for 5 minutes to warm up the diff. That did the trick and they came out. There was about 900ml of fluid left instead of the required 1.3l so I hope no permanent damage was caused.