80srule

I have had my 2004 A8L 4.2 for about 3 years and I've enjoyed the experience. I'm a complete DIYer and do everything from brake jobs to engine rebuilds; and the car has been a little more difficult to work on than my XKR, but overall an enjoyable experience. I've thought parts were reasonable, and service doable. I own VCDS HEX+CAN and the Bentley D3 manual already. I've looked through a bit through the Bentley manual on the W12 to learn a bit about service and read plenty of excellent posts by forum member MP4.2+6.0.

As someone not new to Audis, and not new to the D3, what are the pitfalls and gotchas of the W12? I'm hoping in the next year to spend $20-25k on an early W12 car with 60-90k miles. It will be replacing a 1997 A4 2.8 12V Quattro Auto car with 240k; serving duty behind my XKR in the summer and serving primary duty in the winter alongside my 4.2 A8.

Here's me asking a bunch of questions:

• How difficult is the W12 to work on repairwise?
• What are it's general faults?
• How far from 4.2 specific parts are W12 specific parts pricewise?
• Is the W12 an FSI motor and does it have the carbon buildup issues?
• The W12 appears to be a timing chain motor, are there any issues with the timing components (my XKR V8 had known timing chain tensioner issues) and how long is the serviceable life of them considered to be?
• What would a 75k type service entail?
• Are there any exorbitantly expensive things to repair to look out for when car shopping?
• Is a 2k parts, NOT LABOR, budget per year (8k miles) with a 5k buffer reasonably doable?

MP4.2+6.0

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Yes, parts only but perhaps excluding tires, though you do spec only 8K miles so you could go 2 ½ to 4 years on a set depending on summer vs. A/S. I probably spend $1,000 on core ongoing parts (oil, wiper blades, filters, fluids, etc., and maybe the other $1000 on average on kind of predictable stuff like broken parts here and there (I'm at 8 ½ years on road, 108K now), balances and alignments, something I want cosmetically to improve/freshen, amortizing control arms, etc. That excludes any mods or toy projects. $5K is a good buffer, inclusive of added "start up" fixes like general D3 control arm freshening and alignment, a few trim items, new tires if needed soon, maybe some brakes, some general D3 trunk lid misbehaving, some wheel refinishing/clean up, etc. All this assumes DIY except tire shop kind of stuff, plus where you need specialty equipment like an A/C evacuation and measured recharge. With 450HP that is right there, right now, every time, you will spend somewhat more on tires, brakes and gas, and will smile every mile along the way to growing your carbon footprint of various types. To be clear, if realistically averaging 13 or 14 MPG every day is not for you--except for open road or uncrowded very light suburban--this is not the right choice. And, as you already surmise, you can get eaten alive on a D3 if you bring it in to dealer or even top drawer indy a lot.

TSHong

Great reply as usual by MP. I too have not done any big repairs yet of my 2.5 years of ownership. I am at 76K miles and hope the car serves me well for the rest of my ownership. My goal is around 10 more years. I'm lucky that the torque strut and coolant hoses were replaced when it was at the body shop. I like the D4 interior but the exterior is a little meh to me.

I think your budgeted goal is very doable if you wrench yourself.

80srule

Thanks a ton!!! Your responses are incredibly detailed and from what I'm seeing an A8 W12 is a go next year.

I'm already used to exhorbitant gas, brake and tire bills from my XKR; the supercharged V8 gets about 16 in mostly 55mph backroad driving. The budget I feel is not really for consumables but for actual breakage. So stuff like gas, tires, oil, preventative maintenance, etc; thats not factored into that. I'm not into mods other than things that improve upon a factory design in regards to reliability (ie - Jag tensioners) or replacing with a newer/better design aftermarket part when something breaks. It sounds like I'll be ok!

MP4.2+6.0

FWIW, having looked at D4's repeatedly including the higher end ones as lightly used CPO's, I can never quite get there, at least until they come down to $50K level for loaded, later ones. The wife also has a 2013 loaded Q5. Putting aside highest end fit and finish A8's have, it does have 95% of the latest "tech" stuff the newest D4's have. I could write the check. But to the credit of the existing D3 W12 the combination of well depreciated, lots of preventative maintenance I have done and keeping it virtually all working as new, keeps me coming back to staying happily with it and still seeing it as something pretty unique in the 99.9% case of what is out there, including even here on the affluent SF Peninsula with quasi disposable high end car fashion du jour stuff. It seems to be holding up pretty well as a fairly timeless design, maybe more than the pre-facelift D4's will. Even 10 years + into its original design it can still compete well with nice stuff I literally saw at the car show two days ago, and on evolving areas like tech, it is plenty "good enough" for 90% of the every day higher end comfort and features.

And thus, likewise with DIY and a working understanding of D3's already, you have the right general understanding for what you call actual breakage, plus the ongoing maintenance. To be clear, in my $2000 type total is a combination of : 1.the maintenance (including lots of preventative deep into tranny fluids and such), 2. something that breaks occasionally (usually not anything on the road either, but often by me as part of some other fix, like a connector, hose or other part I push on too much that has gotten old and brittle) and 3. things like the $500 or so I popped for in past year with its 100K "birthday" for a variety of interior soft touch trim. Not broken, but the difference from 100K miles used to still looks new on common touch drivers switch type parts scattered on door, console and overhead. Sometimes it's that $500, or other times the roughly $800 I just spent for the whole front suspension upper arms, alignment, etc. that amortizes over 4 or 5 years of use. I have consciously done a bunch of 100K mile preemptive stuff to "re up" and have it in top notch shape if you will, and it hasn't broken the bank or your guesstimates. DIY is key to that, even more so if you do the extras like I have preemptively and stay inside your total $5K over a period of time.

Bottom, bottom line, the only way as a fellow DIY'er I could see spending at or above $5K in any short period is if I literally blew the tranny up. I don't see that happening w/ motor absent a total fluke. Blown trannies are almost never seen here--essentially the same BTW as the Jag ZF six speed generation, but AWD and somewhat beefed up on cooling in W12 and S8. I have probably been the guy to have done the deepest dives there too, at (pretty advanced) DIY. The D2's and C5 4.2 5 speeds proved commonly to be lemon trannies at 100K, as did many C3's in the mid 80's. Cost me $4+ grand on my C5 for a factory ZF rebuilt via an indy shop. Thus I can sense from prior ownership when the design is stumbling. All in, D3 and W12 are impressive designs; best I've seen in 35+ years of working on Audi's and a variety of other family vehicles, newer and older. Where you get killed is if you buy somewhat over your head because they have depreciated so much for such a nice vehicle, but don't realize it isn't like an everyday mid priced car that once sold for much less when it was new. Letting service people exercise your credit card then has the double whammy of getting hit with not just service bills, but bills beyond one's normal price point for what seemed like a less expensive very nice car up front. If you come from a nice Jag, you probably get this part too.

GnatGoSplat

Starter will probably last forever, but if you do have to replace it, it requires removing engine/transmission assembly.

Serpentine belt requires pulling bumper out into service position so a bit more headache than the V8. Not something that needs changed very often either, though.

MP4.2+6.0

BTDT at about 105K. No different really than 4.2, and done with bumper cover fully on and no other parts removed. Just need the right wrench to get in there to release tensioner pressure. I pulled it only because I thought water pump was starting to leak. Turned out it was a simple upper hose o ring just above the pump. Belt was still in very good condition once I had it off. Very robust and could likely go life of engine.

Yes, starter is hardly ever seen it is so buried. But, I have not had to replace an Audi starter on any Audi I've owned over 1MM + road miles, even on lemon C1's and long term dubious quality C3's.

GnatGoSplat

So service position not needed for the serp belt? Nice work!
I'm not surprised that enterprising DIYers find easier solutions than listed in ELSA.

MP4.2+6.0

Not needed. Just need a fairly shallow wrench set up to get it on tensioner.

volvopentaman

As i bought my second W12 in the summer, i can only recommend!

MP gave a good answer already, i totally agree with him.

I had a 2006 (early 2006 model, mfg late july 2005) W12 A8L from 203->246.000km (126-153tmls). Biggest issues were a bad lambda sensor connector (the Audi dealer mechanic had put pigtails on the leads, BAD BAD!!!), jamming right rear E-brake caliper motor (only needed greasing), intake leak (i replaced the thermostat, and didn't notice that i cracked the injector O-rings to the manifold). And the thermostat (260$ from audiusaparts, 411€ from indy dealer, 488€ from audi dealer, 589€ as non-audi part).

The second A8L i now own (W12 2008 facelift) also has the thermostat as issue, not as bad as the first one. This one had 188.000km when i bought it, and now at 193.000km.

The biggest fear for my second W12 are the carbon (ceramic) brakes, they are **** expensive (rotors totaling 21.000€!!!), luckily the rear ones are replaced under 2yrs ago, and even the factory original fronts look like new. But the pads are expensive too, like 1300€ for rear+front.

The thermostat seems to be the weakest point of the W12, not hard to replace (1-4h), you need to remove the intake manifold&injectors.

Otherwise, mechanically VERY strong engine, no timing chain issues AFAIK, no carbon buildup, and tons of torque all the way from idle to redline.

If you are thinking about an A8, just buy the W12, W12 specific parts aren't more expensive than V8, except the thermostat, and that there are more ignition coils and plugs (coils and plugs are cheap).

The 2K DIY repair budget should be fine, i think i've kept under that on my last one.