09 A6 Avant - tech info

A6 All/ S6 All
#1

Tried posting on another forum, didn’t get much for results. Guess I didn’t ask about polishing my exhaust tips. Anyway, found this forum and am hoping I can get a little more data here. Spent most of my ‘Audi time’ working on the inline 5 cars, so I’m aware how maintenance heavy a 4 ringed car can be. Smart thinking (i.e. not just throwing new parts at it) and smart sourcing (ebay, junkyards) has made owning these cars a fun challenge…most of the time anyway

The wife and I found a line on a nice C6 A6 avant, 3.0T, 2009. 80k on the clock. The engine itself to me is worth the slight hit in mpg over a B7 A4 avant, and although I’m not stoked on the trans I’ll deal. However if I’m going to plop down this kind of cash on a car with 80k I would like it to see it hit the ~200k mileage that the older cars are more than capable of.

What I am after:

*Anyone rebuilt one of the tips yet? Seems like it’s a common ZF transmission and shouldn’t be too bad. I also plan on doing a trans flush + new filter as soon as we get the car (provided we do buy it).
*Adaptive/self leveling headlights - not excited about $1500 headlights. Would it be possible sometime down the road to just set the servos to a locked position, or maybe just cut the power to the servos while leaving the lights intact? Also, if it comes to it - I would bet one could tear into the headlight and just replace the servo instead of a whole new headlight, but I’ve never seen one out of a car and close yet.
*Any good way to easily check for the current level of carbon build up? Something I can do on a test drive. Looks like these motors faired better than the 2.0T’s, but it’s still possible. Not as worried about the gumming up of the air returns on the exhaust side of things, sounds like that only effects the cold weather emissions but please correct me if I am wrong.
*Suspension work - how bad is it? I know it can be a pain, but the C4 S6 platform was a holy goddamn nightmare the way the sway bar linked into the control arms. It seems I’m likely in for front tie rods at some point.
*Anything else really major I need to look for on these?

Thanks folks. Really looking forward to putting the lady into something modern and reliable, so I can get to playing with the coupe and not having to worry about it being her DD.

#2

Wow, welcome to the site. Did I see that you own an C6 facelift A6 3.0T Avant?..in other words, you probably have a rarer car than anyone else on the site. Must have taken a while to find.

  1. Haven’t heard much on this. Do you need to do this, or are you just digging your well before you’re thirsty? There’s a couple of tuned (stage 2 ) C6 3.0T guys on the site and I haven’t heard of any tip problems, even making 375 whp/350 wtq

  2. Not excited as in yours are broken? Or they work fine and you don’t want them to break? I have literally never heard anyone raise a complaint about these other than them needing adjustment. But nothing that would have someone wanting to delete a safety feature that most people lilke. I don’t see the point. You could try to find someone with basic headlights if that existed for the C6, and trade for those from someone and cash…or sell yours…but again, why? Just in case? I would cross that bridge when you get to it because as I siad I haven’t heard of this being an issue to worry about.

  3. No real easy way, either on intake valves or in SAI. Bottom line though is that it’s really not all that bad on the FSI 3.0T cars, so again I would not worry about it. We just saw a 3.0T with 75,000 miles on it and the carbon was a light coating. Not enough to cause a CEL, or interfere with function or choke flow.

  4. Perhaps ynnekdude can comment

  5. There were a couple of recalls early on that I am sure were done long before you bought the car. Otherwise, a few things that tend to go wrong and can be dealt with when they do. The only thing I have seen 3.0T guys deal with proactively is the radiator screen. They have put a protective screen in behind the grill to prevent damage to the heat exchanger from rocks on the highway. The big gaps in the S4 grille made this more of a concern. Not sure if it’s a big deal on a C6

#3

p.s. is coupe short for coupe quattro? Post some pics of it somewhere. We may have a classic Audis section.

#4

welcom to the site… Pictures would be nice to see… You can load them directly to the site. Just look into the upper right hand corner for the load button.

The transmission don’t rebuild it. Flush the fluids post the color of the fluid Vs oem stock… There are a few tip specialists on here that can tell you what fluid to use to save money and the life of the transmission. I know there are a few tip transmissions with the JHM supercharger on them and they have well over 100k on them. JHM took a 135,000 mile tip car and put there supercharger on it for testing with great results. The tip guys can comment but I don’t think your going to need to rebuild it just maintain it.

The lights are they broken… if they are there are a few guys who repair them for like 150 bucks…

sakimano got the rest…

#5

Welcome to AR, B. Rock - you’ve come to the right place for information. +1 on the pic request.

#6

Wow, thanks for the quick reply guys!

In case it wasn’t clear in the first post, we have not bought the car yet. I am trying to do my due dilligence beforehand, but I’ll snag some pics of it. Didn’t think C6 avants were terribly rare, there’s a couple on ebay. This one in particular is a shop loaner car that I ran into last weekend so we’re catching it before it officially goes on sale :wink:

The car does not have those issues - I’m just looking at the car having worked on 20+ yr old audis and trying to get ahead of the game by addressing potential fail points. Sorry if I came off cynical! I had not really factored in that the build quality could have increased and what used to be a problem, may no longer be. Sounds like there are folks out there with minimal issues up into the higher miles.

Yes, coupe is coupe quattro. 1990, red, widebody flares, 2.5L NA stroker. Have 90% the parts to turbo, just waiting for a period where I can have it off of the road so I can put a compression dropping head gasket in and do the valve stem seals.

#7

Welcome!

In regard to suspension work, I’m not familiar with the C4 but the C6 should be much easier. Here’s a thread on AZ detailing a coilover install.

http://www.audizine.com/forum/showthread.php/546164-ST-Coilover-Install-(DIY-sorta)?highlight=coilover+install

I had my water pump fail around 5000 miles. Same issue the B8 S4s had. I also had two defective headlights with failing DRLs replaced under warranty. Otherwise, car has been pretty bulletproof. I burn oil but nothing alarming. In my original, ~43,000 miles of ownership, approximately 30,000 which have been tuned, I have only had to add oil twice.

Very rare indeed. I sort of regret not going that route. I met up with one of the C6 guys and got a ride in his Suzuka Gray facelift 3.0T when I was in Colorado this past summer. Now that is damn rare… 1/1 I believe. Car is APR Stage 2, sitting on KW V1s and BBS RS-GTs.

http://i104.photobucket.com/albums/m180/Thelnferno/Audi/A6%20Avant/0035284f.jpg

#8

Welcome aboard!

Yes, pretty rare, and much more so in the 3.0t.

#9

Well, CO is the land of boosted avants (including Subies by the dozens). That is also where I hail from. Having a vehicle large enough to sleep in or hold 4 people + gear, that doesn’t get wheezy at altitude, goes a long ways out here.

I put up a post in the ‘all german’ section with the CQ.

#10

supercharger will be just like an NA car, other than the intercooling. There’s no adjustment made. It’s a fixed pulley/crank pulley ratio that determines CFM…and then the density (or lack thereof) will still rob you of power.

i.e. a 750 CFM supercharged car vs. a 750 CFM NA car will suffer the same fate

Turbo is the way to go in the clouds.

#11

Huh, I did not know that. Good to know. For some reason I assumed forced induction was forced induction…guess not.

#12

as I understand it…

if you have a supercharger with a pulley and crank pulley sized to spin the supercharger at 20,000 RPMs, and it is feeding the engine with about 750 CFM (let’s say teh one on your car…the TVSr1320 in round figures with a pulley and a tune), your car at sea level should be able to make about 500 hp (150 cubic feet per minute = about 100 horsepower). We will ignore parasitic draw from the blower. We will also assume the blower does not have a boost bleedoff valve that is operational as the one on the 3.0T is when stock. Most of the tunes disable that boost bleedoff, some entirely. So the blower is pushing its max CFM into the engine at all time. On a stock car though, it’s another story.(later)

If we take a Mercedes C63 with the 507 package, and are able to have the engine gulp down 750 CFM naturally aspirated, it too should make about 500 hp at sea level.

If we take you up to 6000 feet of elevation the density of the air (thus the amount of oxygen being fed to your engine) is 18% worse than at sea level. You will lose about 18% of your power because nothing else is changing…yourblower is still pushing 750 CFM and the C63 is still gulping down 750 CFM…but and instead of 500 hp, you are now making about 410 hp.

On a turbo, boost is not limited by the mechanical drive ratio determined by the pulleys vs engine speed. So you can request a level of boost that the turbocharger can spin to achieve. You can increase that with a manual boost controller or in the tune, so you can much more easily compensate. Further, the turbo car can automatically compensate for the lower overall pressure ratio from the less dense air to achieve the desired pressure ratio and CFM to make power. Of course the turbo is likely introducing more heat with more pressure but with effective intercooling, it will have a big advantage over the SC and NA cars which are stuck at XXX CFM.

One case where the SC has the ability to cope with the elevation is when the supercharger is pullied to make XXX power, but has a boost bleedoff valve to keep the CFM driven into the engine in check. This basically means it’s leaving some money on the table. If it is operated based on a pressure ratio, and you move up the mountains, that pressure ratio is less likely to be achieved, so the boost bleedoff might kick in less and less as you climb higher and higher until at a certain point the air is so sparse that the threshold for bleedoff is never met.

On a B8 S4/Q7/Q5/SQ5/A6 the same (mostly) engine is used to make varying levels of power. It can be anywhere from 270 hp to 300 to 320 to 333 to 355. Audi does this primarily, assuming we’re at sea level, by varying how early the boost bleed off comes in and at what PR it does so. Pretty cool. Open it right up, and you make about 400 hp. Put a smaller pulley on and you start making well over 400 hp.

All figures here are at the crank, NOT at the wheels…

#13

^^ good post, Sak. Helpful for those of us who are more mechanically challenged.

#14

I can get the supercharger off a 3.0T in under five minutes so a novice should be able to do it in a half hour or less. It is really easy to pull the supercharger off a 3.0T A6 to check and/or clean the carbon build up.

Does the car have factory air suspension? If it does then I would be very cautious because those front air springs are very expensive to replace. The front air springs get leaks just like the old allroads and all the other Audis equipped with factory air suspension. Otherwise the suspension is just like a normal C6 that is very easy to work on.

#15

Thanks for the explanation saki, a most enjoyable read. A must for anyone who believes moar boost = moar power.

#16

hopefully it is not riddled with errors

#17

Yeah, that makes sense on the sc vs turbo. Thanks for that breakdown My immediate thought was “well, time for an 18% bigger pulley.” However, as this will be a DD and ski/mtb car…it does not need to function as a race car.

I will have to check for the air ride. After the allroads, I have no desire to have an air ride car.

Does yanking off the S/C require the replacement of any gaskets? Do I need to bring torx bits or just a basic socket set?

#18

Also, I really do appreciate all the info so thank you. It seems the vast majority of people with newer cars have dealerships, not toolboxes, to turn to when things break. Which, I can understand when it’s on warranty - but that doesn’t help you when something goes wrong in the middle of nowhere. Good to see people know their way around the newer vehicles!

#19

Well, it took awhile but it’s home:

https://lh3.googleusercontent.com/-fPkqnxAXico/U0Lmj3f2ziI/AAAAAAAABwQ/oNYjyGgYhEM/w958-h538-no/2014-04-04_15-17-21_261.jpg

It’s sitting right at 83k miles. Cold weather package, so heated wheel but no paddles. Black interior w/ dark wood trim. Tight and quiet for the miles.

Needed tires, done. Dealer flushed the PS fluid right before the sale.

Next up is the trans fluid - for the experts, it looks like as this is past the '08 MY it should have the blue G055162A2 lifeguard 8 fluid as opposed to the yellow lifeguard 6? Is there a good way to drain the torque converter for a full drain, or just drain 4 qts twice and call it good enough w/ a new filter?

#20

Congrats on the new ride! Looks great.

Have yet to do a trans flush. Hopefully someone else can chime in.

Really interested on the results and hopefully shift improvement after the flush. Please report back :wink: