Leaking front differential
 

Hi all,
I noticed recently that my beloved ML is beginning to leak gear oil from the front differential. It appears to be leaking from the seal on the driveshaft flange. I was wondering if anyone has any tips to replacing this (Gillybenztech?). More specificaly, is a special tool required to pull the flange off from the differential once I remove the six hex bolts from the CV-type joint to move the driveshaft out of the way or can I just pull it off by hand? I plan on purchasing the seal shortly and am comtemplating doing the job myself. Would this be possible for a fairly advanced DIY'er?

Thanks!

You need a tool to hold the flange while loosening and torquing the flange. I can't remember the torque right now, I'm guessing 100-150nm. The bolts that hold the d-shaft to the flange have to be replaced (and torqued). I recommend also replacing the flange itself, it's not that expensive. There is a special tool to drive the flange seal into the case. Also the typical big-ass socket required to remove the flange nut, but it has to be thin-walled enough to fit into the recess to engage onto the nut, that may pose a problem as most sockets of that dimension are too thick walled(I want to guess at 41mm? I can check at work and get torque specs too, at least I hope I can, our WIS PC is down).
Gilly

Thanks, Gillybenztech; you are always there for us. If you can find the size and torque of the flange nut, I would really appreciate it.

-Gene

Gillybenztech,
Do you have any idea, how much a Mercedes dealership would charge to replace the seal? If it's not that much (and does not take very long), I may just have my local dealership (Rusnak Mercedes) handle this.

Thanks!

Gene:
I'll look in the labor time guide and try to get the r&r time for that seal, and see if I can get some of that other info too. I'm off work this Monday, so probably be Tuesday before i can post the info.
Gilly
ps, just call me Gilly, not the whole gillybenztech, that's a little tedious.

Hi Gilly,
Any luck on those torque values and labor times?

Thanks!

Nah. I started feeling like crap yesterday morning, and didn't even go to work today. I'll hope for tomorrow.
Gilly

Hope you feel better soon. I woke up with a bad headache this morning (occasional migraines). Fortunately, Excedrin came to the rescue.

-Gene

Mine started with a slight sore throat, then within an hour it seemed like all my energy had been tapped, like I hadn't slept for 3 days or something. I finished the work day, but wasn't real proud of the amount of work I had done. Just felt like I'd been run over by a truck, and a lousy truck at that! Added to this was the fact it was the first time I'd ridden my motorcycle to work this season. I wasn't looking forward to the ride home, probably the first time I can say that, because I love to ride. More like a head cold now, doing better, going to work anyways.
Gilly

Well, our WIS is still down. What I know for sure is MB pays on warranty time .9 hour, if you are out of warranty they may charge more.
The torque for the 6 bolts that hold the d-shaft to the flange is 50nm, the drive pinion nut, not much luck. The proper thing to do is to use this tool that measure the amount of force it takes to spin the pinion before removing the pinion flange, then match it up when you are through. It may be as high as 400nm, or higher, to achieve this.
Gilly

Gilly,
I bought the seal already and will be attempting this soon. Can I use regular (chain store variety) gear oil to top off the differential? If, so what brand and viscosity? I also noticed that the drain and fill plugs look like they require a 17mm hex wrench (like the old VW Scirocco I had), is that the correct size? Also, if I marked the pinion nut (and the flange) and tightened back to the same place, do you think I could get away from having to go the pinion nut preload route?

Thanks,
Gene

Gene:
It seems to me that the fill plug is a 14mm.
Yes, 80W90 gear oil is fine in the front diff. Remember that the ETS system uses "open" differentials, nothing fancy in there.
On the flange nut, wow. That's an idea that may work out for you. I wouldn't do it that way, but for a DIY, it may be close enough.
Biggest problem as I see it will be the seal driver, this may be tougher than you think, you know someone at the dealership that'll let you use theirs?
Gilly

Yes, this is an old post, but the info may help someone out. The nut holding the flange to the pinion is 32 mm; the drain & fill plugs are 10 mm. At least that's what they are on my '98 ML320.

Lenny