Just checking to make sure I'm seeing what I think I am.
 

Hey guys,
I'm just getting ready to do a Trans fluid and filter and was looking around under the car and wanted to get some input on what I'm seeing being that I'm new to the world of quattros.

First it looks like I have a Transmission pan seal leak

https://cimg0.ibsrv.net/gimg/www.aud...83d0e6f08d.jpg

Then it looks like, what I think is the center Diff (this is where my lack of quattro knowledge is showing) is leaking, but the cats were still quite warm so I couldn't do too much poking around. There was a Drip of fluid I wiped off to see what it was, it felt like atf, and was redish.... I and the 2nd pic shows oil streaks down both sides of the drive shaft hump

https://cimg2.ibsrv.net/gimg/www.aud...7e13d97f83.jpg



https://cimg5.ibsrv.net/gimg/www.aud...b8f9ae787c.jpg


I'm guessing there is a bad seal etc that is blown on the Diff (assuming that's what it is). From what it looks like, it seems like.... It looks to be that I would have to drop the exhaust, or at least let it hang, remove at least some of the heat shields, then remove the the effected drive shaft(s) or input shaft and then replace the required seal. Does that sound about right?
I'm assuming this is the most likely cause of the humming/whine I hear at 65 to 70 when I take my foot off the gas and then lightly step on it again.

I also found this, it's the drivers side rear outside axle. Both rear outside axles are missing the clamps on the Cv boots but the drivers is spewing grease

https://cimg8.ibsrv.net/gimg/www.aud...57b33c3fc0.jpg


I have felt like a wheel is out of balance, I'm betting this could be the cause :)

Everything else under the car looks really good, just a couple drive line leaks.

I did find out that I need a lower profile floor jack lol, I had to drive on to some pieces of wood in order to get my jack under the car lol

looks like your tail shaft seal has gone bye bye

this is very very common

Audi redesigned this area and a replacement assembly with a double lip seal can be used,. baring that get this kit

Audi A6 Tailshaft Flange Seal – Audi A6 Tailshaft Flange Seal Kit

PS you also blew out a CV joint. get a new boot some grease and repack if you can , otherwise you may be able to just get a half shaft and pop it in.

When you say "blew out a cv joint" do you mean the cv is failing, or that the boot slipped and just lost its grease?

I have been looking at directions on rebooting the CV the and it doesn't look that hard so I am sure it is very do able, or should I not take the risk and just get a new axle?

Just a couple thoughts,
The PO obviously has had issues with the Trans leaking and or shedding bolts (there are at least 5 bolts that are different holding the pan on, you can see them in the first pic, not sure if they are different thread I'll know in a few days when a few more parts get here)

I have read other people say they went with a rubber gasket over the paper one due to leaking, it is all of $4 at Napa, is this a good idea? What about also using some high temp Rtv, form a gasket or the like? And what about some color of threadlocker on the pan bolts to prevent them from loosening?

Looks more like a clamp went away and you're leaking CVJ juice.
 

I would just inject some CVJ juice and reclamp it. It's not likely the joint has been contaminated…the juice looks nice and black. You can get a squeeze container from audi or online. Should be able to fab a small piece of tubing or copper tubing to the container and insert the tube past the boot.

If you want to be anal just pull the axle and remove the boot, clean the joint, replace the boot and fill the joint. IIRC you can also pump CVJ lube into the joint through the axle bolt (remove the bolt!).

Ok cool I was cautious and ordered 2 new boot kits and the output seal for the center Diff.

Now as soon as those get here, I'll get the rubber gasket from Napa for hopefully a better seal on the pan, and then I should be good to go to attack the drive line mid next week... Good thing my S4 hasn't sold yet :-)

I'm kind of anal with this stuff; get the right bolts.
 

You might have to pay a $1.5 or $2.00 per bolt from the dealer, but…
If the PO has queered any of the threads either by putting in bigger bolts or whatever, you should consider repairing the threaded holes in the transmission with helicoil or time-sert or other inserts. The insert-type or helicoil repairs are stronger than stock/OEM.

I use loctite blue on the transmission (and engine) pan bolts. Torque them as specified (according to Loctite), wait 24 hours for the loctite to fully cure. Then you can do the fill procedure on the trans. In a pinch you can wait 10 minutes for the blue loctite to set and do the fill procedure. The heated transmission might hasten the cure.

Some people say with antiseize you torque 20% less and others have found a bolt torqued with loctite will have a larger angular displacement indicating more bolt elongation/stretch but I have not tried this.

The rubber gasket will work/seal for awhile, but
 

it will tend to leak before the paper one. If the trans pan leaks with the paper seal, it's because the pan lip is distorted or the trans mounting surface is damaged. Fix the pan and mounting surface and use the paper gasket. You can use gasket tack/cement (less is more) to hold the gasket in place.

I don't like rubber gaskets that WILL shrink over time and loosen the pan mounting bolts. If you don't use loctite on the mounting bolts they will then loosen and drop out.

Perfect SloopJohnB

What about the rubber gasket or Rtv or form a gasket? I'm sure if torqued properly (I have the zf PDF with the tightening pattern and all torque specs etc), and these aren't required but I don't mind spending a couple extra bucks on a little insurance as long as it isn't going to possibly foul the transmission.

I doubt the threads are fouled, the PO didn't do ANY work himself, so it would have all been done be a shop, so worst case the threads might have been taped out a bit bigger etc but I really doubt the shop would have just shoved a different thread in the hole.