is replacing the timing chain guide a necessity?

[pepe88]

I've heard this is made of plastic and sometimes causes failure. Is it something most of you do?

[m5james]

The labor required to just get to the chain makes it almost cost prohibitive. That, unfortunately, is what broke and caused my 740iL engine to eat itself alive. $13,000 and a month later, I had a new and modified engine in my car.

BMW uses plastic in the engine bay like it's going out of style.

[c4racer]

oh - it can't be that bad. On the 4.2L V8 in my S4 the chains are on the back of the motor. So guess what it takes to get to them? You guessed it - motor pull.

Typically this isn't a problem, but if you have a rattling at start-up that could be the chain guides and you will need to replace them. Generally it is a replace only when they fail kind of deal. And if you get to it soon it should not do major damage to the motor. Notice I say "should". Anything can happen with a mechanical system...

[Vsmvince]

I love my S4. Powder coating my calipers black on monday, and adding the S4 logo clip.

[m5james]

Originally Posted by c4racer

oh - it can't be that bad. On the 4.2L V8 in my S4 the chains are on the back of the motor. So guess what it takes to get to them? You guessed it - motor pull.

Typically this isn't a problem, but if you have a rattling at start-up that could be the chain guides and you will need to replace them. Generally it is a replace only when they fail kind of deal. And if you get to it soon it should not do major damage to the motor. Notice I say "should". Anything can happen with a mechanical system...

Yeah, but does the Audi 4.2L have the same potential timing chain problems the BMW 4.4L have?

Don't forget, rattling at startup can also be a VANOS issue, which is a very common problem w/ the entire M62-S62 line, which is all basically the same block anyways.