Noisy diff

[C Class headaches]

Hello wise ones, I have a c200 cdi auto estate and have just replaced the rear subframe (corrosion issues) everything went well and while the rear end was off, I took the opportunity to change the oil in the rear diff - replacing it with 75w85 gear oil, about 1.1litres. Since then, there is a loud noise (like a worn wheel bearing) coming from the rear which is very noticable from about 30mph. I have had the rear alignment checked and the rear wheel bearings (my first thought) but all is okay - I had new tyres so put the old ones back on to check but the noise is the same.
I used the correct torque settings for everything including the flex discs-driveshaft-dif bolts. Other than changing the oil, I did nothing to the diff so can't understand why it is making a noise. - any suggestions?

I have put the car into neutral whilst at speed and the noise remains the same. There is no difference when cornering left or right.

 

[alexanderfoti]

Did you use a 235.7 spec oil? I can't imagine it would make a noise straight after, even if it was the wrong type. A hard one.

You may want to get underneath with the car in gear (safely!) and check the noise is not coming from the prop center bearing

 

[ajlsl600]

Great ain't it, start off with idea to do basic maintainance and end up with a headache. At times I do ponder wisdom of sitting it out on sofa until forced into situation (I never do tho) if you never loosed pinion.? Difficult to see how you introduced diff issue.
As above, check centre bearing on prop

 

[C Class headaches]

Thanks guys - will try the prop centre bearing and let you know!