I have been trying to locate the source of an oil leak that drips on the catalytic converter. I have looked at the output shaft seal and it is dry. I have cleaned the area and checked everything I can see from below the car, it only seems to leak after the car has been driven at highway speeds. Have run out of ideas. All fluid levels seem normal, even changed the transmission fluid. It looks like tranny fluid but can't find the source. I was told by the previous owner the transmission had been updated to the 2003 model tranny, mine is an 01, and had drain plugs installed. I have looked at them and they look dry. It's getting to the point I am about to remove the tranny.
Thanks!

 

Are you SURE it's dripping on the cats? I, and at least ione other A8 owner that I know of, had a problem with the rear-breather hose. The hose goes from the r/h valve cover (as you are looking at the motor) back to the middle-area, in the rear (up by the firewall). It's a PITA to get to, too.

I'd check there, if I were you. Meanwhile, I'll see if I can locate the online vendor I found the hose from, for less than $80.00 if memory serves...

 

Yes, am sure it's dripping on the CAT's. It's the usual occasional smoke and smell of burning oil. I can clean the cat's and the tranny off, let the car idle for an hour, no leak. Take it out on the highway, the drip starts. That's a great thought about the breather. Have checked everything I can think of but that. Will take a look today. Will the breather have a crack in it? Thanks!

 

If it is a breather hose it will be pretty obvious if you reach back and give them a gentile squeeze. They will be somewhat gummy and degraded.They may even fall apart in your hands.

You are sure this is not your problem? http://www.audipages.com/Tech_Articl...placement.html

 

that is easily checked ( oil or transmission fluid ) one of the has to be low? excalent link there A8AWD

 

I thought that is where the leak was from originally, I even got a new seal. It's wet between that seal and the rear of the pan but dry around the flange seal, it's a very odd location. Can clean it off, let it run, doesn't leak. Take it for a road test, it leaks and can't tell from where. Had a professional mechanic look at it as well and he is scratching his head to. He and I think think the tranny may need to come out to figure it out. Thought someone here may have run across it. Wll go look at the breather hose now. Luckily I have a Kwiklift so I can just drive up on it and check the underside as well as the top.

 

I dont think you will be able to access them from under ther car. Try reaching your hand behind the engine.

Once again, Audipages to the rescue :-)http://www.audipages.com/Tech_Articl...atherhose.html

 

sounds oil pressure related ( are all the engine vents clear ) the engine has to breath

 

Thanks folks! Will give that a look. I was reading the Audipages seal procedure. Do I have to use Audi lube in the gearbox? Any recommendations?
Thanks

 

The tail housing of the gearbox isn't the transmission fluid, its just standard 75w90 gear oil, you can use synthetic if you like as well. Take out the square plug and fill it until the oil starts spilling out the hole and your golden.
I would also get yourself a small mechanics mirror at any auto parts store and get a good look behind the cylinder heads for any possible valve cover gasket leaks as well.