sapman

I just purchased an 07 A8. I was under the impression that with the chains replacement wasn't necessary. But was told by a friend that the experts still recommend replacing them every 100,000. Can anyone affirm or dispute this?

Thanks

MP4.2+6.0

Never touched in practice. Maybe your contact is thinking of the routine timing belt service that applied to pre-2007 4.2's.

bmwm750

Unless you are the .03% who suffers a chain failure (which would lunch the engine), chain replacement isn't part of normal maintenance. He is likely referring to the pre-07's which used a belt.

jakematic

Agreed.

Possibly at much much higher mileage, but guides would be more likely beforehand.
Again at many more miles than 100K

Brozee

I've only heard of changing the gear sprockets that feed the belt, not the belt itself. Over time (much much time and hard use) the sprocket teeth get worn and become much more rounded rather than star like. As the previous posters said, nothing you need to worry about on such a new car. Just drive and enjoy.

sapman

That makes me feel better. My friend's in-laws have a garage, specializing in Audis, and they told him they still like to change them, even on newer models. But this is likely how they treat their own cars, as they are equipped to do so at minimal cost.

Thanks for reassuring me, and more importantly, my wife!

MP4.2+6.0

Have you seen a chain path on a modern Audi FSI motor? Take a look at the picture, that one of the 4.2FSI when it first showed up in the A6. And by the way, you are looking at the back of the motor, not the front. That means the motor comes out of the car to get at it, and that's just for starters. That R+I is perhaps the better part of two days alone. Then think about undoing stuff down to the chains.

Having personally rebuilt several C1 motors--1871 cc inline 4's in the Audi 100LS from 1969 to the mid 70's, which was the last time Audi used a chain to drive the cam all the way until the modern generation--these aren't even remotely similar. And even in those days, you only thought about changing the chain when you rebuilt the motor. And that chain (one, not multiple) running from the crank to the in block cam driving overhead valves similar to your typical classic older design American pushrod, was child's play compared to the modern implementations driving quad OHC's.

bmwm750

Given the obscene complexity (which would require the motor to come out of the car), I can assure you that no one is changing timing chains on these things.....

PaulW

I'm going to say it's not the chain that is going to fail, but the pesky tensioners/chain guides. Hopefully they won't fail like they do on the D2 40v motors!

Step 1: remove engine.....

The rest is easy.

MP4.2+6.0

That many total running feet of chain and multiple ones at that provide endless opportunities for guide and tensioner wear. Guides--many of them all over that picture I posted too.

Still, honestly having pulled really primitive tensioners out of C1's at 100K miles that were really essentially tractor motors underneath, I was amazed the material (even then) held up well and had much life left. Those were simple wind up spring based though; less faith in the hydraulic pressure ones now. Same low wear on their simple single guide plate. Motor had laughable reciprocating mass though, so its real world harsh speed changes and stresses were hardly there by contrast to current motor designs.