The car only has 45k miles on it. its losing coolant at the rate that requires me to refill the tank about every 3 weeks when the sensor on the dash comes on. The dealership has had it for almost 2 weeks and cant find a thing wrong to explain the loss. They did a hot and cold leak down test and those came back fine. Put dye in the coolant tank and cant find a thing with that either, no signs of leakage anywhere. No sign of any dye in the exhaust and no codes have been thrown on the computer. The car runs like new, no issues except to continual loss of fluid that has been going on since late october. Ive gone through over 1 gallon of the coolant, so 2 gals of the mix. Not a sign of leakage anywhere ever, and so signs that the coolant is getting into the engine. ANy ideas?

I have the exact same problem, Seriously I just refill it, but that god awful beep, beep, beep is the worst sound in the morning. I heard it might be a water pump in the back of the engine that needs to be replaced. There is a slight leak and it drips directly onto the driveway! Anyway if they give you an answer please tell.

Its a big mystery as to where the hell this coolant is going. They have checked everything supposedly. They have even had in special audi techs to look at it. Guess these guys travel around and look at issues on cars. They mentioned that the guy was out of the country the first time I took it in. They say that a couple of techs from audi have looked at it.

I had the same issue and it turned out to be the auxillary/secondary water pump leaking. It only got worse as time wore on and I finally had it replaced.

Yeah it's probably the auxillary pump. Shine a flashlight under the intake manifold and see if you spot some crusty pink crap. If so, there's your problem. Also, if it is leaking get the relocation kit installed when you have it fixed...it'll save a lot of time later on.

I wish it were so simple, but you would think an audi dealership would find such a problem in the course of 2 weeks. They even have the dye in there and cant find anything anywhere. I will throw the idea at them and see what they say, but im sure they have looked there. No sings of coolant leaking anywhere, and they have torn part of the car down too. Cost me $450 just to do that, not sure what they took apart but they said they had to tear it down so they could see the engine and turbos better. That is a place that is notriously responsible for such problems isnt it? I think ive heard of others having the issue. Maybe I will get lucky and thats what the problem is.

How long did it take to get worse? Mines been doing this now for about 5 months and has not gotten any worse. Still losing at the sam rate. If that part is bad, wont you find resude around it or leaking to somewhere else in the car? In my case its like the coolant is getting burnt up somewhere.

most common leak is under the plenum on the V6 so cant be detected and it dries up quick with engine heat ( they should use a dye to find the leak ) but that = $$$£££

two most common leak causes are:
- auxiliary pump mentioned above
and
- crack in expansion tank ($25)
Check for spots becoming yellowish toward the bottmo of the tank...
yeah you would think a dealer would have found the cause in 2 weeks but my experience with dealers is not positive so I would suggest you c heck the above two and then take it a good Indy shop specialiazed in Audi.

thanks all for the advice. Going to call tomorrow, saturday and hit them up with questions about some of these problems you all mentioned. Really does sound like it could be that aux pump.

it IS a VERY common cause of the leak and it is not a matter of IF it'llleak but more when :)

By the way, if you they replace it, they have to remove/move the intake at the top of the engine, so while you're at it spend 75-160$ or so on intake spacers/gaskets such as New South Power gaskets or VAST phenolic intake spacers.
I love mine, the engine runs cooler and is torquier atlow and mid RPM's. It'll be no labor since they'll already ahve the intake off.

here's what I have, they are the NewSouth Powergaskets for $75
http://www.gmpperformance.com/index.cfm?PG=detail&PID=159555&VS=1

PowerGasket™ gives you up to 5% more power from your engine by reducing the temperature of the incoming air to your engine. NewSouth Performance has designed an insulating gasket that radically reduces the heat transfer from the cylinder head to the intake manifold. This gives you cooler, denser air for more horsepower and performance from your engine. Made from a high performance polymer, PowerGasket™ conducts on average less than 1/500th of the heat of the steel gasket that it replaces. Your intake manifold will stay 30-50° F cooler and your incoming air will stay 20-30° F cooler. PowerGasket Plus™ is a composite material that has a significantly higher continuous operating temperature than the original PowerGasket and does not require the application of any extra sealant.
http://www.gmpperformance.com/CFJFiles/GMP/8392.jpg
http://www.gmpperformance.com/CFJFiles/GMP/8394.jpg

VAST makes those too, $160








Phenolic Intake Manifold Spacers
[2.7T, 2.2T, 2.3 ...]
$160.00

http://vastperformance.com/shop/images/pixel_trans.gif







http://vastperformance.com/shop/images/piggie_s4_intake_spacer_kit.jpg
Click to enlarge
We're the first to release phenolics for the 2.7T, 2.2T/2.3, and 4.2 motors. Accept no other imitations out there without our research, build and install experience for hundreds of sets to date. These are ~10mm phenolic spacer kits. For the Audi 2.7T, Variations include: S4 intake manifold to S4 heads, RS4 Intake manifold to S4 heads, RS4 intake manifold to RS4 heads. We designed these from scratch and make them by hand. The intake manifold will be insulated from heat conduction through the heads, leading to lower intake air temps -extends the intake runner lengths for better low end torque. Expect a minimum of 5-10hp at the crank. Comes with all gasketing and bolts. Please see our other variants.

Note, on 2.7T installs, ***especially noted for APR BIPIPE USERS****. These fit with any version of bipipe or throttle body boot you may have but some timing belt covers with hard piped bipipes may need slight trimming on the unnecessary timing belt cover threaded bosses. You don't need the screw holes on the timing belt covers on the bipipe. It also helps to install the 2.7T spacers while slightly pushing back on the intake manifold to get good clearance to your mechanical fan.

thanks all. Ill see what they say today or on monday. Will keep everyone posted.

THE VERDICT IS IN !!!!!

Audi called me today and they said the problem lies in one of the turbos. It wasnt a leak after all. He said the turbo was burning up the coolant somehow, mentioned a defect on one or more of the fins on the turbo. Audi is going to take care of it for me, no cost. I will be getting a new pair of turbos installed and should have my car back by monday. The car is out of warranty too! Ive had it for 5 years, but the milage is only 42k. Maybe the decided to be nice because the milage is so low. Anyways, cheers to Audi. Stand up guys and I have a lot of respect for them for how they treated me. I was also given a loaner during the 3 weeks it took them to fix this, no cost to me. All of this is out of warranty.

WOW impressive
ask them for KO4s as they are in a generous mood :)

I'll add my WOW to the comments.

AUDI isn't all bad.... Makes me wonder how they can be such jerks about the MMI issues and then be so giving about the turbo. Maldorf must have the golden touch!

Guess I should mention that the dealership where I bought the car new at has a lifetime warranty on the engine and drive train. Audi took care of it for the dealership, if I understand the manager right. So perhaps it was the influence of the dealership and not me. The end result though is that I was taken care of and the problem is solved.
I DO HAVE ANOTHER ISSUE TO LOOK AT THOUGH! The electronic low oil level indicator is coming on intermittently now. The one that has the sensor sitting on the bottom of the oil pan. They told me to wait and see if it clears up after the turbos are fixed, probably a long shot but who knows. The sensor does not appear to be bad. He mentioned that it could be the cluster in the dash that is bad. Sound right?

They have now replaced both turbos, head gaskets, and some other gaskets in the coolant lines. It is still losing coolant, no affect whatsoever. It takes about 350 miles from filling the coolant tank to where it will set the alarm off on the dash. SO the repairs done havent helped at all. Taking it back to the dealership on Monday. Everyone is stumped. ANyone have ideas? If you read this whole post youll see how they have exhausted about every option. Even called in a tech from Audi central to look at it. No signs of leaking anywhere, no traces of the dye.

Head Gasket??? The water has to be going somewhere!

They replaced both head gaskets and set the heads off to a shop to have them checked out. Its got to be something internal in the engine. I think the next step is a new engine.

Anyone got any other ideas?

Well, maybe the third time will be the charm .This time the audi engineer decided that it was the oil cooler. Much cheaper part than replacing two turbos, wonder why they didnt try this first. Well, ive had the car for 1 week now and it hasnt lost any coolant! I think this might me the end of my problem. Anyone else ever hear of the oil cooler causing this mysterious coolant loss in the 2.7t?

Well, its been about 2 months and the fluid level is still holding. looks like the problem has been found. Anyone else had this experience where a faulty oil cooler causes coolant loss in this manner?

I have a 2000 2.7 and I had the same problem. Mine was the auxillary pump. The dealership charged about $850 for that. I also had a cracked expansion tank. They also charged $1000 to change about $20 worth of O-rings that were on coolant lines to the transmission and something else. I would say that your problem is most likely the aux pump. Good Luck.