Rear diff / haldex problems

[tomsko]

I know I'm probably starting to annoy people here with my questions, but please be kind..
So I've owned my S3 for a couple of months. I come from a place where people don't change oil and fix issues the cheap way so my 2nd hand S3 fell victim for that as well...

Basically I have multiple issues with my drivetrain. First of all, the rear diff is whining. After doing some research on this forum it appears that people just get a new 2nd hand rear diff instead of figuring out this stuff. I will try topping up a little oil enhancer and see what it does, but overall replacing the diff is a way to go I think?

Another problem is that I have 100% locked rear diff and I think haldex is not functioning at all (everything is just locked). Both rear wheels turn with the front right wheel together. I will try the handbrake trick when I get my car back. The old owner said he had inserted plates or something in Haldex to do this lock (and it does help with acceleration) but overall it's just breaking my car. I've heard people do this when Haldex stops working, to at least get a car that moves.

 

[<tuffty/>]

You have answered your own question on the second 'problem'... the problem is whatever the previous owner has done... so return it to standard at the very least before working out how next to proceed...

Chances are the haldex is already damaged in which case replacing the diff/haldex setup will potentially fix both your issues..

Nobody in their right mind permanently engages the haldex when it stops working...a faulty haldex certainly doesn't prevent the car from being driven as its FWD most of the time anyway

<tuffty/>

 

[tomsko]

You have answered your own question on the second 'problem'... the problem is whatever the previous owner has done... so return it to standard at the very least before working out how next to proceed...

Chances are the haldex is already damaged in which case replacing the diff/haldex setup will potentially fix both your issues..

Nobody in their right mind permanently engages the haldex when it stops working...a faulty haldex certainly doesn't prevent the car from being driven as its FWD most of the time anyway

<tuffty/>

Probably not worth trying to return it to standard as damage has been done, so new Diff/haldex setup is prob better choice.
Do you have any tips for things to watch out when buying these items?

 

[<tuffty/>]

nothing other than make sure you can return it if it doesn't work... they are old parts and prone to the same issues that befell yours...

<tuffty/>