2003 S4 engine question
 

Does the 4.2 V8 have a cam belt, or a chain? I saw some pictures with a
chain, so I guess its the latter, but I am not totally sure.

Thanks,

Chip.

Re: 2003 S4 engine question
 

On Mon, 1 Sep 2003 12:35:02 +0100, "Chip" <AnneOnymouse@virgin.net> wrote:

>Does the 4.2 V8 have a cam belt, or a chain? I saw some pictures with a
>chain, so I guess its the latter, but I am not totally sure.

It uses a chain - which is a damned good thing considering it is at the *back*
of the engine ;-)

Re: 2003 S4 engine question
 

They went to a chain because it was narrower than the belt. With a belt the
engine didn't fit in.

"Chip" <AnneOnymouse@virgin.net> wrote in message
news:bivas6$djfem$1@ID-185713.news.uni-berlin.de...
> Does the 4.2 V8 have a cam belt, or a chain? I saw some pictures with a
> chain, so I guess its the latter, but I am not totally sure.
>
> Thanks,
>
> Chip.
>
>

Re: 2003 S4 engine question
 

"Charles Fox" <cafox513@gte.net> wrote in message
news:1sw6b.8331$98.4931@nwrddc03.gnilink.net...
> They went to a chain because it was narrower than the belt. With a belt
the
> engine didn't fit in.
>
> "Chip" <AnneOnymouse@virgin.net> wrote in message
> news:bivas6$djfem$1@ID-185713.news.uni-berlin.de...
> > Does the 4.2 V8 have a cam belt, or a chain? I saw some pictures with a
> > chain, so I guess its the latter, but I am not totally sure.
> >
> > Thanks,
> >
> > Chip.

I thought that relocating the cam drive to the rear of the engine was the
space-saving feature. The switch to a chain from a belt was because the new
rearward location made regular changes of a belt impractical.

This might be a dumb question, but why doesn't Audi do away with timing
belts on *every* engine? FTM, why don't *all* auto manufacturers do away
with them? A chain drive -- or even better yet, direct gear drive -- for
the camshaft(s) is much more reliable than a belt. No more worrying about
whether Audi's service recommendations are accurate; no more
multi-thousand-dollar engine repair bills if you ignorantly believe Audi's
exaggerated timing belt longevity claims. No longer will essentially
complete and immediate obliteration of the engine be the collateral result
of a seized water pump or tension roller.

Do chain- or gear-driven camshafts generate too much noise? Do they impose
additional drag on the engine? Are they that much more expensive than
belts? Or are most automakers simply unconcerned about the long-term
reliability of their cars? A cynic would claim that the automakers
intentionally build their cars to fail shortly after the warranty period,
because vehicle longevity reduces new car sales. Personally, I've never
accepted this claim. But sometimes the evidence does seem to point in that
direction. There must be a reason why belts continue to be used to drive
engines' camshafts (other than Audi's secret desire for all their cars to
die 4 years after they're built). Can anyone offer some insight as to what
this reason might be?

- Greg

--
1976 Cadillac Fleetwood 9-passenger sedan
1989 Audi 200TQ sedan
1990 Audi V8Q
2000 Oldsmobile Intrigue
2001 Chevy Astro AWD

Re: 2003 S4 engine question
 

"daytripper" <day_trippr@REMOVEyahoo.com> wrote in message
news:rovplv8qgrh73ohsibcbc8gnqbn0p6tfam@4ax.com...

<snip>

> Audi is hardly alone with cam belts in their engine line-up, I bet most
> mainstream engines are belt driven these days.
>
> Belts are usually quieter than chain drives, and are usually lighter than
> chain drives. Gear drives are difficult to eliminate excess lash
(something
> tensioners do for chains and belts) and tend to whine.

I guess my personal preference for bullet-proof dependability over
aesthetics (and even at a modest weight expense) are trumped by others'
preferences (for reduced weight and noise) and for other design
considerations.

And I honestly hadn't thought about lash in a gear-driven setup. Actually,
the only gear-driven cams I've ever seen were on older GM 8-cylinder
engines. (I'm not even sure whether they were aftermarket-only or available
right from the factory.) They appeared to be indestructible, which is why
that design sticks in my head. Perhaps sloppy timing (as would result from
excessive gear lash) isn't as detrimental to these older engines as it would
be to modern ones.

- Greg

--
1976 Cadillac Fleetwood 9-passenger sedan
1989 Audi 200TQ sedan
1990 Audi V8Q
2000 Oldsmobile Intrigue
2001 Chevy Astro AWD