Leaky Rear Differential

[mrfatboy]

My rear differential has a leak.  I guess it's about a drip a day if that. Can anybody help with suggestions on how to fix this?  Is it a DIY job or too much of a pain in the butt?  I have no idea what is entailed.

I have attached some pictures where I see the drips coming from.  It seems mostly from where the drive shaft connects to the differential.

Any help would be appreciated.



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1969 280sl
Signal Red
4 Speed

[ja17]

Hello,

It is usually the rear pinion seal. More of a eyesore than a problem. Replacement requires disconnecting the drive shaft at the rear. A special spanner socket is required to remove the slotted nut. There is some procedure which must be followed for re-installing the nut. You will need to mark the position or install a new "crush sleeve" and toque to specs. The seal is easily replaced the housing it mounts in can be removed with the seal enabling the change to be done on the workbench or everything can be done under the car with the housing in place. There is a lot of information already in the posts on changing differentials.

This leak is common, and rarily gets bad enough to cause much concern. If the mess on the garage floor bothers you, replace the seal it is inexpensive. Otherwise check you axle oil level a couple times a year. You will find that it really does not loose much.

Joe Alexander
Blacklick, Ohio

[mrfatboy]

thanks joe,

I did alot of reading of other posts on the subject but I did not know it was the rear pinion seal. There were not alot of pictures    I can now go back reread those posts and get the details.

1969 280sl
Signal Red
4 Speed

[jeffc280sl]

Here is what you need.

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Jeff C.
1970 280SL 4-speed

[jeffc280sl]

Here are some pics of the components.

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Jeff C.
1970 280SL 4-speed

[jeffc280sl]

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Jeff C.
1970 280SL 4-speed

[jeffc280sl]

When doing this job you should replace the oil seal and paper gasket.

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Jeff C.
1970 280SL 4-speed

[mrfatboy]

jeff,

Thanks for all the pics.  Have you done this job before?

1969 280sl
Signal Red
4 Speed

[jeffc280sl]

You're welcome.  Yes I have done this job before with the axle removed.  I think others have done this job with the axle still mounted. Ask away if you have more questions.

Jeff C.
1970 280SL 4-speed

[mrfatboy]

Well, since you are offering

The axle will still be mounted.  I only have 8" riser/ramps to drive the rear end up so I can get underneath the car.  It's still cramped however but better.

1) Is it possible and worth it to do this job in this setup?

2) Do I need that special slot socket tool? Is there something else I could use? Where can I get that tool?

3) How much time to you think it would take to do this job in this situtation?

Like Joe said, it's just an annoyance to me but I have the time but I know what to get in over my head and/or create more problems.

If I choose to move forward in this task I'm sure I will have more questions.

1969 280sl
Signal Red
4 Speed

[jeffc280sl]

Not sure what you mean about a jump in the setup.

You will need the slotted socket.  I suggest you search for Mercedes tools and enter their part number for the socket from the instructions.

Its hard for me to estimate time.  Maybe 3 to 4 hours.  The pin socket is the most expensive item to purchase.  The seal is maybe $20 and the gasket $7.  With the correct pin socket the job is pretty easy.  Make sure to index things as per the instructions so that they are returned to the assembly in the same way they were originally installed.  This makes it easier when re-tightening the slotted nut.

How handy are you?  You can make a pin socket from a old socket if you are good with a grinder.  It is important that you get it as close as possible to the MB nut slots or it will slip out of place.

Jeff C.
1970 280SL 4-speed

[mrfatboy]

lol, i thought I corrected that typo before I sent the post.  It's corrected now. My brain and hands don't always work together.

 I think I saw in another post a picture of the handmade slotted socket.  I am reasonable handy and your pictures and help should give me the confidence to do the project.

1969 280sl
Signal Red
4 Speed

[jeffc280sl]

Great!  

If you make the socket I suggest you spend the time and make a good pin socket that fits snuggly in the slotted nut.  I think I remember somewhere reading the nut is $60 to $70.  Don't mess it and the threads up with a tool that isn't just right.  I made several and I speak from experience.

Good luck!

Jeff C.
1970 280SL 4-speed

[Benz Dr.]

A drop a day? You're worried about ONE drop per day? Do you know how long it takes to leak out enough oil that you need to refill it?

 At any rate it might be filled too much. I've seen where they leak until a certain point and then slow down to almost nothing. I like to see a fair sized spot on the floor or a lot of oil everywhere before looking at some of these messy jobs. Then there's always the small chance you actually make it worse by '' fixing it. ''

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[mrfatboy]

i'm not worried about it. I just got tired of looking at the oil puddle for the last 15 years.  It would give me something to do

1969 280sl
Signal Red
4 Speed

[doitwright]

As Dan mentioned, I have read that it is not unusual for the differential to get overfilled because it is often done with the car on a lift.  When on a lift, and the rear wheels hanging down, oil from the diff will flow into the axle tube.  When the car is set back on the ground, the wheels rise and the oil flows back toward the diff.

Frank Koronkiewicz
Willowbrook, Illinois

1970 280SL Light Ivory

[mrfatboy]

I just topped off the differential. It was down about 1/2 quart.  The axle was under load when I did it.

1969 280sl
Signal Red
4 Speed