If you think its damaged, which is low on the list, drain and replace oil. If noise goes

Spray diff with degreaser in a can, hose off 1st. Change oil out, then see where its leaking from.

Bazzle

 

If you think its damaged, which is low on the list, drain and replace oil. If noise goes

Spray diff with degreaser in a can, hose off 1st. Change oil out, then see where its leaking from.

I was thinking if replacing oil - it would make sense to replace the leaking gasket, if going thru trouble of replacing a leaking gasket - might as well replace them all.

 

Is it really leaking ? MB's have a querk of misting, So it has a bit of oil on it but not leaking, Clean it off and see how it looks, Any drip on the floor where it parks?

 

Is it really leaking ? MB's have a querk of misting, So it has a bit of oil on it but not leaking, Clean it off and see how it looks, Any drip on the floor where it parks?

Not a single drop on the floor.
Pics:

 

Hmm steam it off and keep an eye on it, It may just be misting, That has probs taken years to get like that.

 

Based on your photos, I think you have leak. How many miles on car and has the fluid ever been replaced? I have 125K miles on mine and there is absolutely no fluid on the outside. I'm not sure what the "misting" effect that others have mentioned but I believe that you should not be seeing this. The only time I saw something like this was on my old Blazer when a pinhole had rusted through the cover. fluid leaked through the pinhole and wicked all over looking similar to yours. Have you removed the fill plug and checked the level?

I would start with Bazzle's suggestion and watch what happens with fresh fluid and everything cleaned up. It is a simple job to drain and refill. If you want to try anthing additional while it is drained, I would replace the cover seal and inspect the cover for severe external rust but nothing beyond that to begin with.

 

Some of the oil turns to vapor and seeps past the seal the reforms on the steel parts and put a very thin mist on them, as it builds up looks like a diff leak, MB;s seem to suffer alot with it, But not worth doing in most cases. As I have been told by a gearbox and diff rebuilder , When i took some MB's to him.


Change the diff oil, Go's without saying, Should have said it maybe

 

Car has 55K, diff fluid was changed about 2 years ago at 40K. Used Mobil1 gear oil with proper viscosity. At the time of last change - it had oil on it, but probably less. I doubt there is any rust there. BTW - car is parked for winter and even after months of seating - there is not a drop on a floor.

Is it safe to use powerwasher on it ?

 

when i got my diff serviced they noticed it was "leaking". i have not noticed a drop where i park. it looks like its weeping which i dont think is critical it happens on a lot of MB's. in my case the breather hose from the diff is clogged causing it to do this. to get to it (this is what MB told me) they have to drop the diff = $$ in labour.

ill have a look one day when i have the car up on stands to see where the breather for the diff is.

 

breather is on top:
Êàòàëîã

 

pOWER WASH IS OK BUT DONE PUT REAL CLOSE TO SEALS OR BREATHER.
uSE A CAN OF DEGREASER IST TO MAKE IT EASY.
(Woops Caps lock)

Side seals do breathe as stated, yours looks like at 1st glance a leaking plug?

Bazzle

 

To me it also looks like a leak. Check the underside of the car as well - if it's from the fromt seal, there be a spray across the width of the car on the undertray as the oil gets thrown by the driveshaft rotation. If its the side seals, the spray will be lengthwise underneath the car. But from what I can see of your photos, it is either the rear cover or the drain plug. Did they use a sealant on the plug when the oil was last changed? You are supposed to use a sealing compound on the drain plug.

 

You may also try to tighten the bolts on the rear seal - maybe they've worked loose.

 

Do you know which kind ? Not sure about last time, but for the next time I want to have it done righ.

 

There is a special MB recommended one - which nobody seems to be able to get. I just bought some at my local Autozone and it seems to be O.K. I'll check the name when I get home. It should be basically a non-hardening type so that you can get the plug out next time. There is different types all with different 'break forces' (the amount of torque you have to apply to break the bond formed). I choose one with a low break point.

Also on tracking the leak, something I've done in the past on some of my other cars. Clean the area properly. Take some Johnsons baby powder and sprinkle/rub the whole area very well until its white all over (well, it is the bottom of the car as well ). Drive a few miles until the oil is hot and see if you can see where it is leaking. If not yet leaking, increase the distance and have a look again, etc.

 

Just want to share some reasearch.

Used differentials 400-600$, seals were updated at some point (was told by MB technician, no links to information)

For comparison - set of new tires is 700$

 

MB recommends cleaning the threads of the plug with Loctite 7063 cleaning fluid and then apply Omnifit sealing compound 100H. They also recommend using a new plug each time. The tightening torque is 50 Nm.

 

For what its worth, a quick wrap of teflon plumbers tape on the drain plug makes for a cheap, easily found, seal. Makes install and removal easy. No leaking after 5000 mi. Clean and dry threads thoroughly. Let me know what you think I may have to change!

 

Lots of talk here, and that's a good thing, but you'll never find out anything unless you clean the housing, and check the oil level.
If you fear that there MAY be damage, have an oil analysis done on the oil in the diff. They cost about $20 to $35 and will give you the info that you want. While the analysis is being done, just refill the diff. with the correct oil and wait to see.
This is a no lose situation, if it’s only a slight leak, you have no problem. If it is a leak from the drain plug, you will see it. If there is a loss of oil, you will know that, and have refilled. If damage has occurred your analysis will tell you, and pretty much what you have to replace.
The sooner you start, the sooner you will know…

 

Lots of talk here, and that's a good thing, but you'll never find out anything unless you clean the housing, and check the oil level.
If you fear that there MAY be damage, have an oil analysis done on the oil in the diff. They cost about $20 to $35 and will give you the info that you want. While the analysis is being done, just refill the diff. with the correct oil and wait to see.
This is a no lose situation, if it’s only a slight leak, you have no problem. If it is a leak from the drain plug, you will see it. If there is a loss of oil, you will know that, and have refilled. If damage has occurred your analysis will tell you, and pretty much what you have to replace.
The sooner you start, the sooner you will know…

Thanks Bruce, my main problem is wining noise when car is moving. I want to get it fixed.

My next step is get the car on the lift and see if noise is still there when tires is off the ground.

While the car on the lift - i am going to take the fill plug out and see what's there.

 

Thanks Bruce, my main problem is wining noise when car is moving. I want to get it fixed.

My next step is get the car on the lift and see if noise is still there when tires is off the ground.

While the car on the lift - i am going to take the fill plug out and see what's there.

As long as it's up there, wash it down. Plenty of great grease cutting produdts out there to help you.
I like the purple stuff that ZEP puts out, you can get it at Home Depot. Wear gloves and DON'T get it in your eyes. Brush it in then wash off with water as soon as possible because it tends to eat aluminum.... (Not really funny, but true......) The area will be spotless.

 

I see somebody had already posted the recommended sealer to use. I couldn't get it, so I just used one of the Permatex products. Don't have the package anymore, but I think it was the one with the lowest shearing point and non-hardening. It also said that it contains Teflon.

 

As long as it's up there, wash it down. Plenty of great grease cutting produdts out there to help you.
I like the purple stuff that ZEP puts out, you can get it at Home Depot. Wear gloves and DON'T get it in your eyes. Brush it in then wash off with water as soon as possible because it tends to eat aluminum.... (Not really funny, but true......) The area will be spotless.

Unfortunately - I can play too long on that lift (it's in a shop of a guy i know) so the bath time will have to wait. Depending on what I'll find - i may just put the rear end on jacks on my driveway and powerwash it.

 

Back from the friend's shop

When running on the lift with tires in the air - no noises from diff. Took the fill plug out - oil level was down maybe 1/4-1/2 inch. Filled it up which half bottle of Mobil1 75w90 - most of the half bottle ended up on the floor, but i guess 100-200ml went in. All diff bolts are tight. It looks like it is leaking is from the rear seal and a little from drain plug.

While I was there his guy balanced my rear tires. (fronts were balanced when i did brakes in June)

Right rear is pretty worn (i had puncture in left one - and it's somewhat newer)

Now I think the noise is coming from tires. I will keep this set till the winter and get a new set next spring. I will get the diff flushed and drain plug replaced with new one and put it on thread sealer.

Now when I drive the car - I think the noise is less loud, may tire balancing helped, or may be it's the same.

 

Worn tire(s) can cause all sort of strange vibrations. When I got my car out of winter storage earlier this year and started driving it, I thought the front wheel bearings were going. Turned out to be worn tires. Since the fluid level was only down a small amount, the worn tire is very likely the culprit. Good luck.