Well as it turns out the crosspipe must have been modfied on the 05 and newer 3.0 engines. It does not have the hexagone head as in previous versions (see photos) and the area was totally dry and clean when I finally got to it.
There is another area close by with the white deposit from dried up coolant and I am trying to identify a hose that would allow for a lot of coolant to leak once the engine is hot.
Does anyone have a coolant flow diagram for an 05?
I am bummed and disappointed but I want to get to the bottom of this and get this card back on the road.

 

ziggy-

turns out the nipple was NOT the source of my leak. thankfully i realized that about halfway through pulling stuff out to get there. i did get my hands on a cooling system diagram and realized that there are at least two seals on the crossover pipe that are also very prone to leaks in this area. knowing i was never going to be able to get all the way down there on my own, i finally took it to an audi mechanic and made him suffer the pain instead. He replaced all of the seals in sight while back there, all of which ended up being about 3 hours of labor.

i'm happy to share the cooling diagram with you (and anyone else for that matter), though i received it via fax from the dealer and once scanned, it's far too big to post here. send me your email and i can email it to you (or any others who would like to have it).

hope that helps -

jw

 

JW, thank you for the diagram offer!
You can sent it to zippy_gg@yahoo.com.
I'll try take pictures of the surgery in hope that it will help others in the same predicament.

 

It sure is different back there, i see the nipple where the hose goes in, but it looks like audi has changed the design for it to be welded in. Doesn't seem like it stopped it from leaking any coolant behind the engine LOL!!! The crossover pipe itself will have two O-rings on each side going into the cylinder heads. Thats what im assuming the mechanic replaced. Un-less someone wants to post this diagram on here.......

 

That's what it seems like, the little washers on the nipple.

 

I've posted a jpg of the coolant diagram here for those interested:



And a pdf of the same thing here:

http://actiongrab.com/jw/stuff/coolant_diagram.pdf

 

Well if it isn't the nipple thats leaking it would most likely be the crossover pipe o-rings which is #14 in the diagram. The ECT sensor is a possibility too, but thats more on the passenger's side.

 

The area where 14 is located (on both sides) is dry and clean (no white deposit at all). I think the leak may be coming from #13. I'll have a chat with the parts guy at the dealership and maybe a tech. I must not be the only person with a leak on the back of the 2005 V6 engine...
I hope to get some tips and pointers.
I suspect a seal dried out when the car sat for 7 months on an unprotected lot, when the car never got driven, or at least not long enough to open the thermostat and allow the coolant to flow through the system.

 

I've replaced a couple of those seals as well, but its not common from that spot. You will need to order all the O-rings anyway because you will be removing the entire cross over pipe to get at that seal. Might as well replace all of them while you're in there.

 

Time to revive that thread. Long story short, the car is still sitting in my driveway after I took all the plastic components and connectors apart. I checked for leaks and reassembled. Once again the engine leak coolant oly when hot, but it is not coming from the crossover pipe or anywhere near that region. I was able to confirm that everything was dry by looking with a light. However I can see coolant falling on the ground, in line with the whels of the car and closer to the driver side than the passenger side. I have removed the engine and transmission undercarriage cover plates and when crawling under the car I cannot see where the coolant is coming from, too many components in the way. Coolant drips from the transmission housing near the engine but the leak is actually somewhere higher... Just can't see where from.
Any suggestions, or similar experience?
Heating systems? Heater core?
I cannot find a diagram either...