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W108 - Leaking from differential, need help

6K views 5 replies 2 participants last post by  Scoot 
#1 ·
Hi Benzworld

A few days ago, my W108 280 SE suddenly began dripping oil from the diff. It's not just a few drips, you can definitely see some marks on the ground around the size of a tea cup's diameter. It only happens if the car has been driven and the fluid is warm.

Here are some pictures of the issue:
The big seal, which is dry:


The smaller one, which is wet:


As you can see, the big seal around the left rear axle is totally fine and dry. The issue is on the other seal towards the right rear axle (the smaller one).

How hard is it to replace that seal? I will discuss the issue with my mechanic on Monday as I'm going in with a tiny clutch issue, however this totally caught me off guard.

And a last question - from my understanding, to top off the differential, I just pump 80/90 EP Fluid into the filler hole until it comes out? I've never owned a car with a pendulum rear axle so this is all new to me. Do you people have any fluid recommendations?

Thank you for reading.
 
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#2 ·
I think replacing the CV boot on the right side of the differential is a total pain in the ass, and is best done using special Mercedes pliers to install the special Mercedes staples. Others use hog nose (hog ring?) pliers. I've done it once and I have no desire to ever do it again.
 
#3 ·
You are absolutely correct. I had the car on a lift today and it's the CV boot leaking. However, we noticed the metal strap around the boot was not tightened properly (could take two full rotations on the screw). I'm refilling the diff before next drive and I'll make sure to see if the tightening of the boot might have helped.

I bought some Castrol EP-90 (GL-4) to refill it with. I was looking into buying the same but in GL-5 spec, but I was told it would wear harder on the diff.
 
#4 ·
Feel the boot. Is it soft and pliable? The replacement boot is a split boot (because it has to be) the original boot is not split. If you had the entire rear end out of the car you could replace it with the not-split boot which would be nice, but few people actually do this.
 
#5 ·
I'll make sure to check but I really do hope that we solved at least some of the dripping by tightening that boot clamp which was somewhat loose. I really don't want to disassemble the rear end as the differential itself was replaced in 2004. I think the CV-boot just dried up slightly as the car wasn't used a lot.
 
#6 ·
If the differential was replaced in 2004 then chances are that the boot was replaced at the same time. If that's the case, it should be good. They last a long time.
 
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