i saw some yellowish oil on my drive way and when i jacked up the car, this part was pretty wet so i am assuming that's where the oil came from. it is in the rears. both sides has them and the one that is pictured is the one on the left rear. what is this? and what is it for anyways?



different angle

 

id guess a sensor wire.

 

would help if the picture wasnt all drawn on.

 

From those pictures, I have no idea where that even is on your car.

 

 

My car's in the air, so I felt around a little bit.
It seems that on the left this hose goes to the haldex, and on the right it goes to the rear diff. Haldex fluid is like a yellowish-amber color, so that could explain the fluid aspect. However I'm still confused as to why Audi did this. Unless it's meant to be like an oil cooler or vacuum line. I have no idea where this hose goes once it's in the frame... for obvious reasons.

I'll look around in the manual.

Alright found it! But this doesn't explain your fluid...
Inspect the rubber angled part for rips. If it's not coming from the brakes or this vacuum hose. You might want to check the fill plug for the haldex, the filter, the rear diff drain/fill area. Good luck and keep us updated!

 

I can't tell in the pictures. But its common for the tt's to leak anti-rust oil from inside the frame rails, right at the rear lift points. That fluid is clear-yellow-ish and follows wires very easily. If this is the problem, no need to worry.

 

^^^ The rear lift point is right in that area. Move the rubber lift point around and see if it's covered in fluid.

 

no leaks in the haldex unit, i recently changed the haldex fluid so i was thinking that i might not have tighten the plugs enough, but when i lift it off, there was no sight on leaks on haldex but then i saw those so maybe those are for haldex over flowing or breather.

 

Correct.. its the vent tube. If you overfilled it, or got it too hot, it will drain out of the vent.... Kinda 'self levels' the fluid.