Alexandroff

hi again guys! as a good friend of mine bought himself a 2004 Audi A8 4.2 with the BFM engine, he was told the chains are to be done... my questions - do we have to change the tensioners as well, or can we renew the pads and chains only? do the tensioners go bad after certain time/mileage? many thanks

Junius

If I were you, I would renew the tensioner and chains to save time, money and headaches in the long run. You can buy some good quality tensioner and chains from ECS Tuning.com for way less than the dealership. I just did mine a month ago and my car is still holding up pretty good with ECS parts

EHLO

I smell a dishonest repair shop.
Up through 2006 it's a timing belt.
Also, they know (or should know) that 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.

Junius

Well not necessarily. Even though the 2004-2006 4.2 v8 had a timing belt, there are also chains and adjusters on each bank of cylinders for the variable valve timing system that is incorporated into the engine. The question is if it's notoriously rattling while driving and at hot idle....that would indicate a chain tensioner problem that needs to be taken care of as soon as possible. In a lot of cases, it would throw a cam position (usually retarded) code and MIL. I had the same problem, that's why I know

EHLO

Good to know, thanks.
Here's a reference video;

Junius

Yes, the older 4.2 engine from the D2 is very similar to the early D3 setup. That is a very good reference video.

dradoc

I am wanting to purchase a 2007 A6 with a 4.2 engine...it has 125,000 miles and seems to have been serviced and maintained well. But some naysayers are telling me the timing chain problems will soon arise....any thought please? How long do these last? Does it have a chain or a belt? Is 125,000 considered high mileage? Thanks

MP4.2+6.0

Welcome.

Read sticky and search some more first. Been posted on and debated at length in recent weeks in other threads specific to the chains vs. belt change that occurred on the D3 4.2 i 2007, including w/ my input. No need to repeat here.

richard-tx

I purposely bought a 06 A8. Sure it has a timing belt that needs to be be replaced every 80k-100k miles. I don't have to clean carbon or worry about timing chain or guide issues that requires the engine be pulled on the 2007 and later engines.

If I wanted to buy an 04-06 with 125k on the clock and it has not had the timing belt changed, I would have it towed to the dealer or reputable independent and have the timing belt changed along with the water pump. If the belt fails, it is an expensive fix.

Alexandroff

ok, so far so good. We changed both tensioners, started the engine and drove the car about 500 km. What i don`t like is that the car has no power, especially in lower revs. Vagcom shows now faults but the car remains somehow sluggish. What bothers me is that we might have not aligned the chains correctly.
In accordance to what i have read and what i saw as i got my tensioners changed by the local dealer, there is a slight difference between the number of notches/ chain links on every bank/side. While between the camshaft marks on bank 2 (right side when you stand in front of the vehicle) the distance has to be exact 16 notches/links of the timing chain, on bank 1 it is a few mm less than 16 notches. Is that correct? If not, i`m afraid the gear of the camshaft might have skipped a few degrees? Any hints or ideas?