is this leakage indicating a faulty seal? or to be expected, trying 2 replace fluid in rear dif this weekend,

thoughts?

pinion side shows def fluidish buildup?


back half is greasy as sin

what fluid do you recommend? red line?

Looks like new seal time to me. In the mean time be sure not to let it get low on lube.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

There is no such thing as a normal oil leak on a car. Replace the seal.

Virtually every oldish Merc diff has oil seeps and weeps.

But you might as well wait until they start leaving the odd spot of oil on the ground before repairing them. This can take years to progress to that stage.

Yours is a little wet and looks to be getting closer to that time. Park on a clean area after a good run that warms the diff. Check for oil spots next day.

In the old days when the Brits built motorcycles, all of them use to leak oil. It would drip from the crankcase, it would drip from the gearbox, it would drip from places where there was not supposed to be oil. If they ever stopped leaking oil we knew that there was no oil left in the system. Jaguar cars were much the same.

We thought it was normal. It was not until the Japanese starting building motorcyles that we knew any different.

I heartily agree with the 'normal' state of oil seepage from the differential, but if you want to do the seal(s), the pinion is the scary one, for me anyway. There's a 'black magic' setting of the pinion to gear which is disturbed and must be re-set to change this seal. The axle seals are easier, as I understand it, but you'll need to remove the respective axle to change the seal.
Both my babies weep gear oil. On the SL, the car is new to me so I have no idea how long the seepage has been there. My plan is to clean it all up (done), check the oil level, change the oil, then watch the situation. Maybe an additive to help the seal might be a good idea if it persists.
My now retired indy once mentioned to me that 'they all leak there', and that's after over 30 years servicing Mercedes. He would enjoy fixing this for a customer of cour$e, but for me, I got the distinct impression that the job didn't justify the seriousness of the problem. I live with it on the SE.

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1986 560SL
2002 Toyota Camry
1993 Lexus

black magic setting = pinion backlash

if i measure the new seal versus old and shim for difference backlash should be unchanged correct?

how big is the pinion nut? i prob dont have big enough impact socket yet.

what is the rear dif seal, paper? anyone have a part number or source.


axle seals look fine, seems like the back plate is leaking the most, looks pretty ez 2 put some permatex aircraft sealant on there and stop its leakage.

Thanks!

Lok for the diff vent on top ..they have a filter and they get plugged, causing weapage at pinion seal from heat pressure build-up.
It is also caused by too mich fluid at top off..you want it just below the fill hole.

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A Dalton

If you do it according to the FSM its a bit more complicated than that - they want you to torque the pinion nut until a specified amount of torque is required to turn the differential assembly. They also want the CV joints and halfshafts to be in the horizontal position IIRC.

I've heard of people doing this job by just putting the pinion nut back in EXACTLY the same position as the old one. I have no first hand experience with this matter so YMMV.

The differential on my 91 300D weeps a bit - it might leave a drop every 3rd or 4th day when parked overnight. I agree with prior posters, it would have to get a lot worse before I'd change the seal.

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98 Dodge-Cummins pickup (123k)
99 CLK320 (352K)
08 SL550 (113K)
13 GLK250 (86K)
14 E250 (61k)

Arthur - Is the vent/leaking seal applicable to the W210 diff too?

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Not sure ..you will have to look, as that is just a suggestion.

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A Dalton

im so fast only 3 months later and I got fluid changed (old stuff had some lumps in it) with valvoline syntehtic mixed with lucas gear oil.

great stuff, hints,
need 14 mm hex socket, prob have to hammer it in
5" 1/2 drive extension bar for fill side to clear exhaust
on drain plug, u push it towards front of car to unscrew, somehow i did this wrong for 10 minutes

reccomend a 'sta lube' type pump $8 to refill (tho it didnt fit the quart bottle or a gallon bottle perfectly it did pump fluid awesome)

i had previously cleaned off a part of the dif to see how fast it 'releaked'
and it was still clean, way too slow of a leak for me to fix


and TIP

when you unscrew that drain plug, dont lay there looking up at the stream of fluid spilling down, wondering 'where is my catch pan?'

thats a messy clean up


i could nt find the vent on top?( probbably due to sliminess of diff) but i did measure and finger check fluid level on refill, so its set for next 60K miles i guess



no pictorial i got too slimy from spilled fluid