A4 Quattro rear diff knock?

[saintjon]

Hi all, I have a random metallic knock noise every so often from somewhere near rear passenger side wheel. Often when gently accelerating in slow traffic. Had look underneath as suspected loose exhaust or suspension mount. Couldn't see anything there but rear diff has signs of oil leak on both side output shafts, and slight up and down play on shafts that gives metallic noise...
Guess the seals have gone and running dry, how hard to replace? Could there be further damage (speculative I know) or could replacing seals and re topping with oil solve (not sure if this is exactly the problem, but not good!).
A4, 3.0 Quattro Avant, Auto, Tiptronic

Thanks for any advice!

[noscream]

saintjon said:

Hi all, I have a random metallic knock noise every so often from somewhere near rear passenger side wheel. Often when gently accelerating in slow traffic. Had look underneath as suspected loose exhaust or suspension mount. Couldn't see anything there but rear diff has signs of oil leak on both side output shafts, and slight up and down play on shafts that gives metallic noise...
Guess the seals have gone and running dry, how hard to replace? Could there be further damage (speculative I know) or could replacing seals and re topping with oil solve (not sure if this is exactly the problem, but not good!).
A4, 3.0 Quattro Avant, Auto, Tiptronic

Thanks for any advice!

Suspension mount, exhaust mount, wheel bearing... anti roll bars, bushes...
diffs are generally good for a very long time... even if there is oil leak evidence, take it to a garage for inspection and know for sure....

Even if is has low oil, chances are it could just be oil seals, the shafts normally do move to match the suspension position. go to a garage is my suggestion.

One other thing if you had run low on oil (before running out, if you have), the noise from the diff. would of been considerable, like an aircraft drown from inside the car cabin.


Garage step 1.

[saintjon]

Thanks, think I need to spend more time under there looking at other potential rather than going for the worst!

Theres no other noises from it, ie no grumbling etc. Will see about getting an oil change for peace of mind and start looking all over the rest of the components.

Cheers.