I purchased a USED a6 about two weeks ago and it drove fine for about a week then my wife drove the car to work the light came on to add coolant. No Coolant in the system and no leaks in our garage or anyplace we have ever parked. Its just gone? I check the oil and it looked fine. I did notice some water coming out of the exhaust but no much at all ( not sure if that is a sign of something ) I'm new to tha Audi world and I'm hoping people can help me out. I did look under the car today 11/18/13 to see what I can find and I do have a picture of what I think could probably be it? I have no ramps or jacks at my house so It is a reach for me to get to the spot of liquid.

Here the picture is

 

I could not get the image to work. As far as the water out of the tailpipe that is completely normal. One of the byproducts of combustion is H2O.
Also keep in mind you should have a large splash shield underneath the vehicle so determining where the fluid is leaking from the engine would be difficult.
Might want to bring it into a shop to have them pressure test the cooling system & pull the pan.

 

Not sure if you have the same problem, but on my son's 2000 A6 2.7T, the aux coolant pump was leaking enough so that the coolant level would drop, but no sign of leakage from under car. Aux coolant pump is a common leak spot. It's nested underneath the intake manifold & when it leaks it puddles in that area & evaporates off as it's heated by the engine. We changed the aux pump & problem solved. It's difficult to see into the valley by the aux pump, but you can get glimpses between some of the intake ports. Another way we checked was to fish a dry paper towel around on the end of a flexible wire. If it comes out wet, aux pump is likely leaking.

 

This is an update. I was looking at the motor last night and I noticed the fallowing in the pictures.

Sorry for how dirty the engine is. I didn't purcahse the car that long ago.




Any ideas what is making the leak?

 

Either the secondary coolant pump or the coolant cross over pipe. You're going to have to probably take off the intake manifold to get a good look.

 

This might be a dumb question but around how much are they?

 

I had my secondary coolant pump replaced at the dealer for around 900 about three years ago now. This was before I was really into the automotive scene. The pump on its own it's about 200 from FCPEuro.

 

You're talking about the Auxiliary pump correct?

 

Yes, the terms are interchangeable.

 

Here is a picture of your cooling system. 13 is the aux water pump, and that hose 14 would be suspect of a leak as well. The pump 13 is 145.08 and in stock. But Audi makes a relocation kit 078-998-998 for 187.75 and it's location is represented by #50 although the pump doesn't look exactly like that. It moves it down to that lower passenger side area in front of the block. You'd need 2 intake gaskets also at 8.37 each and a gallon of coolant, Audi brand is 18.10 but you may have some of that available to you locally. What this kit does is replace the 13 water pump with a plastic elbow, would be a good idea to get replacement hoses in that area too since the manifold will be off anyway. A harness is included so the new pump mounted farther away has the electrical power supply connection to it.