Chiro

The axle seals on E320 4Matic 1998 rear differential are leaking. It has been suggested that I try a seal conditioner additive to soften the seals . Does any one have any experience with this. I can't find a specific differential additive . I also need the size of Allen key needed to remove the plug..I think it is a 17 mm ..can anyone confirm. The problem has only recently started and I have 60000 miles (100000KM) .

Chiro

Well , no one has responded to my posts so let me tell you where I'm at. The differential drain and filler plug is a 14 mm hex , I used a 1/2 inch drive socket which I recommend ,especially if this is the first time it has been removed as it is tight.. You will need a small extension if using it on the W210 wagon but not the sedan. I drained the gear oil after removing the drain plug at the bottom of the differential on the right side of the car . The differential holds 1.3 liters of gear lube.I refilled it with Pennsoil 85/95 gear lube approx $5 per liter here in Canada.
Mercedes wanted $65 a liter for there product. I didn't quite fill the differential , left room for 200mm (just under 8 ounces). I filled the rest of the differential with Gunk Transmission Fluid Treatment with the intention of it softening the seals and resolving my leak. I cleaned off the undercarriage and differential casing and will check in a few weeks for further loss of fluid. If the leaking has resolved I then plan to drain the fluid again and add Mobil Synthetic Gear Lube..$15 a liter (quart). I'll keep you posted. I will add that my leak looked quite bad but when I drained out the fluid it measures 1 litre, so I had only lost 200-300 mm.

Eurosport

nice work, hopefully that stopped it.

jaak

Sure you don't want to just drop it out and change the seals? It may be possible to put the car on ramps, and get the axles out by dropping the diff, change the seals, put it back up, and refill it.

Air Marshall Eldritch

I'm getting this done tomorrow, coincidentally. The seal design has been changed in shape because the old design was flawed. 3.5 hour job to drop the axle and open it up to pop in the new seal design.

Chiro

Just to update. I drained out the Pennsoil and haave replaced it with Mobil syn. I'll be checking in a couple of months to see what took place . So far no oil on the ground. Let us know how much it cost in the end to have the new seals installed

jaak

I dropped mine and changed them in 2.5 hours. In my garage on ramps. But I didn't take a coffee and Gewurzplatzchen break.