awdinut

I have an '04 and am wanting to get a single grille A8. The 2008 models got some changes that I like, but I am leaning toward a 2006 because its the last timing belt year; and I am concerned about the longevity of the chain engines. An A6 chain engine with chain problems is common enough that the 2 indie shops here have both seen cases. They dont have any A8 chain customers, so no data available from them on that topic however.

Any high mileage 2008s out there in AW Land ?

dvs_dave

On this forum at least it doesn't seem to be an issue with A8's. Although given that the same engines are used in A8's it must just be down to the fact that there are much fewer of them in comparison to A4 and A6 models using the same engines and timing chain arrangements.

So basically an A8 with a chain motor is just as likely to suffer from chain tensioner issues as any other Audi model using that particular engine variant.

So roll the dice...

Pothole5000

I know b6 S4 4.2's had chain guide issues. But I believe it's a slightly different set up then our 4.2's.

EHLO

As Pothole5000 states, the timing chain 40v non FSI V8 used in the 2004 and up S4 and A6 had chain guide cracking problems, but the timing chain 32v FSI V8 in the 2007 and up A8 is a newer design that doesn't have the issue.
Pick your poison, replace the timing belt of the 2003 to 2006 non FSI V8 per maintenance schedule, or clean the carbon deposits in the intake valve area of the 2007 and up FSI V8 as needed.

awdinut

I dont know that any of the AW member's chain A8s have gotten 150K+ miles yet...that's one of the things I am hoping to find out here.

EHLO

Again, it's not the same engine, I wouldn't expect any such problem with the V8 in the A8.

GradecEngineering

To the OP, I currently have 177K on my '08. I hope to go many more. Stop worrying and drive what makes you happy.

Your choice of words are strong.

There's nothing basic about the engineering behind these cars. The two timing chain systems may "look" similar to a layman, but I can assure you that every component in that motor is designed for that particular motor. You know what happens when you assume, right?

I wouldn't call carbon cleaning these motors poison. It only takes about 45 min to get to the valves comfortably. Aside from the cleaning supplies, the only other cost is a new set of manifold gaskets.

A timing belt job on the other hand....

EHLO

The eventual need to clean carbon buildup could be considered a design defect, agreed that it's not in the same category as the poor design choice of using a finite life timing belt that could bin the engine, but a maintenance chore regardless.
R8/Huracan V10 and a version of the VAG I4 EA888 have both direct and port injectors, the latter primarily to help reduce emissions, but a side effect is to substantially reduce carbon buildup.
I hope VAG applies this technology to more of their engines.

dvs_dave

It's not something to specifically worry about or put you off a car (unless it's already ticking!). But the fact that the timing gear is all at the back of the engine and not designed to be replaced means that if there is any problem with it, however small (e.g a $20 tensioner pad) it's a massive engine out job to sort. Whilst timing chains don't need any scheduled maintenance, just like anything they are by no means immune from wear or component failure.

Given that there are numerous examples out there of issues occurring with this timing chain arrangement on other Audi's it's naieve to think that the version of it used in A8 engines will not be subject to occasional problems.

A timing belt on the other hand is a known entity, is designed to be easily replaced, and even then it's only a few times in a lifetime job.

Worst case it's something that could relegate one car to the scrap heap due to the repair cost vs an every day timing belt change and you're good to go for another 75-100k with the other.

For what it's worth, I was talking to my local Indy and he had an S4 in with a cracked tensioner....$9k to fix. That's 4-500k miles worth of timing belt services given he'd just done my 75k service with full timing gear for $1600.

Panelhead

I wished mine had a 2007 or later engine. The air box removal to change the filter, timing belt change.
But the carbon built up, and issues with oil leaks on top of the engine have balanced the issues. I read more the PITA small oil leaks around the top mounted filter. Course, you hear the leaks and not the others with none.
ButI am happy mine has a 2005 4.2.