Whining noise coming from rear of car

[jason2084]

Hi. I'm new to this forum as I've just bought my first Audi A3.

I was hoping someone here can help me!

I've got a 2.0 TDI Quattro and noticed a couple of days after buying it that there is a whining noise coming from the rear of the car, sounds like near side, when i lift off the throttle and decelerate from 80mph. 

The noise can be heard at lower and higher speeds but its most noticeable between 80 down to 70mph.

Another couple of things to add is that the noise goes away when i apply the brakes, and the noise is still present when out of gear.

I took it to an Audi specialist and the identified the following:

- No abnormal noise from wheel bearings

- NSR brake disc face corroded/lipped/scored

- Suspect scraping noise is brake pad picking g up on brake disc lip

- Rear prop shaft bush is split, but with correct movement of the outer weight

- Rear diff drive shaft oil seal has slight leak but oil level ok

- Rear diff output shaft has excessive movement, expect this is due to a worn bearing in rear diff, expect this is the reason for the noise.

Based on this, i took it to a gearbox/diff specialist for a refurbished and they were reluctant to work on it as they weren't convinced the noise was from the diff.

Another thing to note (not sure if relevant) is that when changing lanes on the motorway, the rear of the car squirms a bit when moving over the middle of the road/white lines.

Anyone else experienced this or know what the noise might be?

Thanks in advance for your help!

[rbdazza]

tell the mrs to sit on the other side and see if the noise goes with her ;)

in all seriousness, when changing lanes that can be common, especially with wider tyres. why not change the rear discs and pads as a matter of course then take things from there. usually wining noises are bearings, being a quattro changing the rears will be a bit more of a job than our more friendly FWDs. 

[jason2084]

I was waiting for someone to make that joke! 

So you think try and eliminate the easier/cheaper bits first, so get brakes done and see if the noise goes away. Sounds like a good idea as i was going to get the rear discs and pads done anyway as they are a bit rough.

Cheers for the advice

 

[cliffcoggin]

Worn differentials are known to whine when decelerating. You tell us there is an oil leak from the diff and excessive slack in the output shaft. It seems an open and shut case to me of a clapped out diff.

[jason2084]

Thanks Cliff. That's what i thought. Not sure why the diff specialists were reluctant to start work on it?