Noisy differentials

[SomethingRattling]

I have a C240 - 2000yr (w202) chassis. It has developed a whining noise from the diffs which has progressively got worse over the last 2 weeks. I noticed a spray of oil underneath the car from the diffs to the rear plus the diffs were coated in oil. Recently took it to a garage (not Mercedes as it may be condemned) They drained the diffs and topped up with Oil (BV 75W-80W) and a treatment additive (WYN64505?). This apparently builds up the rubber seals? If this fails to resolve the problem then we are talking about replacing the seals on the diff (£800 incl) and possibly new crown pinion (add. £400). I have since looked under the car and it does appear that the oil is coming from the drive shafts. Having read that replacement of the diffs takes approx. 2 hrs having undone 4 x bolts to drop the shaft to gain access to the rear plate and several torque bolts i am tempted to have a go at this myself. Has anyone else done this? and are there any pit falls i should be aware of? So far the only engineering i have done on this car is replacing the crankshaft sensor which went surprisingly well (only one bolt!).

 

[television]

Setting up crown wheel and pinions is a specialist job, the teeth of the crown wheel need to be blued for the correct mesh, otherwise it will whine.
On the ones that I have done, the pinion nose could be unbolted from the main housing and a shim fitted to obtain corrct mesh, With the MB the pinion is inserted from the inside and the whole thing has to be put together before it can be checked. This is made possible by better engineering tolerances.
There will always be a warning that the pinion may have to be replaced if run for a long period on a faulty bearing, though I have never found this to be the case, new bearings have done the job, goog enough., The removal and refitting of seals does require special tool and drifts.
If the diff is not very noisy when full of oil, it should be OK with just the bearings.

I would go to a differencial specialist who could do the job much faster than MB as they are doing it all day long, and it comes under standard engineering practice.

Malcolm

 

[television]

Forgot that the vents on your car cause problems by forcing the oil out of the vents, there are modified vents to stop this, I would wash it down to see where the oil is coming from.

malcolm

 

[SomethingRattling]

Many thanks for such a prompt reply! Given the tight tolerances you mention i believe its beyond my capabilities and will take your advice on finding a differential specialist. With reference to the vents i take it that these are located somewhere on the diff housing? If i can locate them i will certainly clean and check prior to any other work. On a final note could you recommend a differential specialist in the Berkshire area?

Once again many thanks.