MP4.2+6.0

I have to say, I just love the echo chamber effect on some of this chain stuff. If you want to own about the most complicated chain drive available, get a W12 like mine. And frankly, about zero worries by me. And unlike so much of the echo chamber stuff here, never has there been a post on this board that I recall of any chain failure on either a D3 W12 or a 4.2. I only recall one reported W12 motor failure at all, which was a guy who supposedly bought one knowing it had a zero compression situation in one cylinder, but with little other info ever posted.

Frankly, having owned three belt Audis (1985 Audi 5000 2.2L I5, 1996 A6 2.8 V6, and 2000 A6 4.2) and serviced a couple more for friends and family, I'm glad to be done with them. Need to sell my complete tool set sometime and wash my hands of it. Accept it over not, but Audi has now pretty much phased out its belt motors. Having been around before belts became common, the shift happened in general as a way to make cheaper high volume OHC motors, and at least originally quiet them down and package them a little tighter. Essentially it shifted production cost from manufacturers to maintenance cost to owners over time. Yes they were good enough, but honestly I got tired of the brain dead "vee know better" design that buried the thermostat and such behind the belt, always has you wondering at a belt change how many dollars to throw at the variety of parts that comprise the whole system, and having no good statistical data on failure rates or specific components at issue. If I didn't DIY it, am I spending $1200 to $2000 against a .01% risk, a .1% risk, a 1% risk or a 10% risk? Stated that way, I probably wouldn't "buy" the insurance in the first two cases, and would in the last. But, no real data on what the rate is. Apparently nothing like 10%, but could be any of those first three.

Meantime on FSI's frankly I think the chain concern is misplaced relative to the available data. That is, as EHLO mentioned, I don't recall a single D3 4.2 chain related failure reported here, having been here the whole time FSI 4.2's were sold from new. There have been a few 4.2 belt ones, but not many either. But, we do know a proverbial %#$load of cash has been spent to maintain them, a variety of owner angst, and some dumped ones shortly before the interval came up. And likewise, carbon fouling? Not that I recall specific to the D3 4.2 (S4 4.2's don't count for example...); a few with S8's with it.

BUT, in all the sturm and drang here about belts and chains, the ones I do remember on FSI's are fuel. All the D3's can have occasional tank related pump issues, but there have been a number of incidents/posts IIRC on failure of the high pressure components. Thus, if I were to take a hard look at the 4.2 FSI set up, honestly it would be more on the actual reported cases--fuel, not chain drive and not particularly carbon fouling either. Aside from those, there are the often hard to resolve 4.2 general SAI issues, the long term intake flap system reliability, and the really hard to service cooling fitting that are real world reported from time to time.

Final notes on long term high level D3 watch/maintenance areas: Panelhead, good summary on various D3 watch areas/long term maintenance items. Make #2 both front AND rear upper control arms. I used to say/think front too, but detailed inspection of mine (subject of a prior long post) showed rears were worn as much or worse than fronts. Detailed pics in reply 22 to my own post about control arms linked in my sig. below. Also, add various long term air suspension issues, though still knocking on the highly polished wood with mine all good at 10 years and 113K. Throw in TPMS sensors every six years, now much cost reduced for many owners who use aftermarket equivalents at much lower prices.

Dusty280z

Holy crap so the W12 I was looking as has a traumatic carfax report. 3 accidents. 1 in the front, 1 in the rear, and 1 side impact that caused a airbag to deploy and required a tow. I think I'm going to look elsewhere.

dvs_dave

Agreed that problems seem few and far between with little out there specific to the V8 FSI at the moment. Although the V6 gas and diesel engines in the D3 A8 suffer similarly with the chains, so there's some examples of this system being problematic in the D3.

Anyway, as an engineer myself, placing such a complex system in such an inaccessible spot where just a $20 component is the most likely failure point is scary from a longevity/repair standpoint.

Of course Audi (and everyone else) don't really care about that...warranty period only. Reason they went for such a unique solution was not because it was the best, but because the inherent quattro layout slings the engine out in front of the front axle which is bad for handling. Audi are often criticized for this so in an attempt to improve things without a total reconfiguration of the car's layout, they had to find a way to move c of g of the engine further backward, and the front axle further forward. They achieved this by shortening the engine slightly by using timing chains, and then moving the timing system and some of the ancillaries to the back of the engine. The axle move had already happened with the introduction of the ZF 6HP trans as the front axle now runs through the bell housing in front of the torque converter. Another benefit of chains is that they are fractionally more fuel efficient which is worth a fortune to manufacturers these days.

So in short the rear timing chain thing is a very complex solution (how typically German) to make up for bigger shortcomings with respect to the overall drivetrain layout. If Audi didn't insist on having their lesser versions FWD, then such ludicrously complex compromises wouldn't be necessary and they would be able to engineer a properly laid out AWD system like Mercedes, BMW, Jaguar, Lexus, Infinity etc have as they don't have a FWD consideration to worry about. I hope finally the D5 is able to address this properly as VAG products will always play second fiddle dynamically until this is addressed.

GradecEngineering

The timing components on the FSI motors are not the most likely failure point. There is zero evidence to support that.

There is no universal chain "system" that Audi uses. Every engine design is unique so I wouldn't compare the V6 to the V8.

EHLO

You've hit on one of my biggest disappointments with Audi; the engine hanging out front.
The other being eventual carbon buildup in the intake valve area, although at least one version of the latest generation EA888 I4 and the R8/Huracan V10 use an additional set of port injectors, so things are improving there.
I look at my S8 and think how much better it would look (and handle) if it was a front middle engine design, but don't expect this to change with the D5.
At least for the D series one would think that they could drop FWD engine options.
Likewise Porsche could eliminate the vestigial 991 rear seats, stretch the wheelbase and reverse the engine, bringing it to a proper rear middle location.

dvs_dave

Where have I said that the timing system is "the" most likely thing to fail on the engine? All I'm saying is that if you are unlucky enough have trouble with it, it'll be a real headache. For some reason you're taking umbrage to the suggestion that problems are even a possibility.

In terms of the actual likelihood of failures, problems with or resulting from the DI system are way more likely to give you trouble on an FSI before the timing system will. First gen tech teething troubles etc.

Dusty280z

2006 AUDI A8 L 4.2L

I pick it up on Friday. I am so freakin excited. I did not pay that price btw.

ltooz_a6_a8_q7

Perfect combo. Looks well kept. Good find. Make sure every thing works before signing the contract or consummate the deal.

Cheers,

Louis

JohnnyJ A6Q

Hello Dusty,

Did you yourself run an AutoCheck, I have it if you want me to post pdf, I think you should check it out as to the info just added 6/18/2015 and 6/22/2015, also look closely at that rear bumper and passenger side trunk mounted tail light, NOT trying to rain on your parade, but as sometimes we are to excited to look closely and miss things, I have done it myself....

ltooz_a6_a8_q7

He may not care about the rework...

Cheers,

Louis