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Discussion Starter · #1 ·
I have a refundable deposit on an '08 S5. 46,700 miles, 6-speed manual - went for a short drive in it last Saturday.

No price or terms negotiated yet, but if it works out, I can get it tomorrow evening. If not, I can wash my hands of the idea and be out nothing but my time.

Any major issues or sticking points with the 4.2 in '08? I know the 3.0T is a great engine but I have four (older) forced-induction VWs already, and am looking to change things up.

I'm more concerned with long-term reliability than "ultimate power", and the 4.2 is priced within reach.

Open-minded to anyone's input here!
 

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the carbon buildup is a pretty significant problem from what I've heard. Again, all hearsay.
 

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the carbon buildup is a pretty significant problem from what I've heard. Again, all hearsay.
Wasn't that only affecting the 4.2 in the rs4?

I would get it only if you can get an extended warranty of some sort, personally. Otherwise I'd try to hold out for a 3.0t because that engine is marvelous.
 

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Discussion Starter · #6 ·
I heard about the carbon issue, but I thought it was limited to the S4... Wow, that may not be the case!

This is not a CPO car, unfortunately, but extended warranty is available. Cost of that may not make this a deal.
 

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I heard about the carbon issue, but I thought it was limited to the S4... Wow, that may not be the case!

This is not a CPO car, unfortunately, but extended warranty is available. Cost of that may not make this a deal.
Carbon buildup seems to affect most of VAG's engines with DI, which isn't rare among other manufacturers either!
I don't know if VAG have worked it out on the new engines with both direct and indirect injection but I guess it's too early to say since those engines were introduced together with the Mk7 Golf AFAIK.

Honestly, if the car you're looking at runs strong and doesn't show any of the symptons, I wouldn't worry to much. The odds are carbon deposits will buildup sooner or later but it isn't devastating. I rememeber googling this issue a time ago and saw a bunch of DIYs. I'm not completely sure but I believe they say you may have to clean the intakes/valves every 60k miles. Consider it like any other routine service.
 

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First of all, carbon buildup is not guaranteed. I'm not sure if anyone has actually figured out a set of circumstances that will not produce it, but it's not something you necessarily need to count on. If it worries you, then stay away, but if you can treat occasional cleanings as preventative maintenance (they are not that expensive at independent shops), they they are a honey of an engine, sound great, and are very reliable (sure you will run into isolated bad eggs, but that happens with everything).

And I am not speaking from internet experience here. I put ~23k miles and 4.5 years on a 09 S5 I bought new, I have put 65k and 3 years on a Q5 3.2 (engine is basically the same minus 2 cylinders) I bought new, I bought an out of warranty R8 4.2, and I wrench on a 75k mile FSI A6 4.2 (same exact engine).
 

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also, not sure where you lie with doing your own work, but a few things to note.

-They use top mounted oil filters, which makes changes easy, but potentially messy.
-They take 11qts of oil
-The alternator is the only belt powered accessory, everything else is shaft driven off gear sets (and aren't necessarily easily accessible).
-If it's your first FSI engine, note they ALL tick at idle, it's the injector solenoids, not necesarily the valvetrain or chains.
 

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First of all, carbon buildup is not guaranteed. I'm not sure if anyone has actually figured out a set of circumstances that will not produce it, but it's not something you necessarily need to count on. If it worries you, then stay away, but if you can treat occasional cleanings as preventative maintenance (they are not that expensive at independent shops), they they are a honey of an engine, sound great, and are very reliable (sure you will run into isolated bad eggs, but that happens with everything).

And I am not speaking from internet experience here. I put ~23k miles and 4.5 years on a 09 S5 I bought new, I have put 65k and 3 years on a Q5 3.2 (engine is basically the same minus 2 cylinders) I bought new, I bought an out of warranty R8 4.2, and I wrench on a 75k mile FSI A6 4.2 (same exact engine).
How is that R8 doing?
 

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V8 Gen 1 S5s look, and sound so much better then the new ones. The only bummer is that you are stuck with the same power. Not much you can do to make the fast besides a super charger that costs as much as a used e46 m3.

That being said they are my favorite looking cars, and from what I have heard the 4.2 is pretty bulletproof.

If we only got the sportback here

 

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the carbon buildup is a pretty significant problem from what I've heard. Again, all hearsay.
It depends on your definition of significant. RS4s can lose as much as 40 hp as the carbon builds up. But the engine still runs just fine, and it's still making 380hp. Eventually you might get enough of an obstructed valve that you start throwing error codes. But that's rare, and if it happens you can usually cajole Audi into covering the cleaning. Personally I consider it a regular service item to be done at 30,000-40,000 mile intervals. They tend to run 7-8 hours of labor for the more effective manual scrubbing/cleaning that requires removing the manifold. (spraying solvents into the intake manifold won't really do anything by itself)
 

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Discussion Starter · #13 ·
also, not sure where you lie with doing your own work, but a few things to note.

-They use top mounted oil filters, which makes changes easy, but potentially messy.
-They take 11qts of oil
-The alternator is the only belt powered accessory, everything else is shaft driven off gear sets (and aren't necessarily easily accessible).
-If it's your first FSI engine, note they ALL tick at idle, it's the injector solenoids, not necesarily the valvetrain or chains.
I've had good luck with my 2 2.0T engines -owned the '06 since new, and the 189K '07 since it was at 141K. No cam follower problems with either - and no oil loss with the high-mileage one. As I read through the carbon cleaning threads, I noticed they mentioned carbon buildup issues with the 2.0T as well. But I've never had that kind of issue with either of my 2.0Ts.

Looks fairly straightforward to clean the carbon on the 4.2, though it looks to be a huge pain in the a**. Once a year, I could deal with it.

What worries me on the 4.2 is the chains (guides). Any concerns with longevity there that you've seen? I bought one 2.0T used and dodged a bullet (tensioner guide was destroyed on the camshaft timing chain, but I replaced before it failed catastrophically).

That chain was simply to get to. Engine timing chain guides on the 4.2 are probably a different story entirely.

I appreciate the help thus far - I need to build these points into the maint. budget if I end up getting it.


Car did run strong and seemed to start with no hiccups. No check engine or diag. warnings that I could see. But my exposure to the car has been very short thus far.
 

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If it's a good deal and the car you want I would get the 4.2 V8. Has much more character and sound over the 3.0T, which honestly sounds like garbage. Sure you can tune and add pulleys to the 3.0T, but if you wanted a 400hp car to begin with you should be looking at other things.
 

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What worries me on the 4.2 is the chains (guides). Any concerns with longevity there that you've seen? I bought one 2.0T used and dodged a bullet (tensioner guide was destroyed on the camshaft timing chain, but I replaced before it failed catastrophically).
The FSI motors, while still using chains, do not have the issues the 40v engines had.
 

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Guys,

2014 Audi rs5.... i know this engine has different internals in comparison to the s5 which had the similar 4.2 v8...

Is the carbon buildup still a concern... it seems like it would be due to similar/same cams and valvetrain. Would you ignore the audi rs5 as a purchase option? Obviously i dont want to keep paying for carbon removal and have the engine taken apart to be cleaned.

Whats the reality here?
 

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The reality is that your in for a bunch of research....RS's post is a good one. It seems YMMV. Tons of info on the web on this.

That being said, if its under warranty I really wouldnt sweat it. The S5 i mentioned earlier was under a CPO warranty and the dealership was balking at paying for the cleaning (car was in and out of the shop for missfires/CEL due to carbon).

My indy mechanic rough quoted me 1K to do a carbon clean on a V10fsi motor in an S8. I could chalk that up to the price you pay to play if it was once a year deal.

*And this is all second hand experience to be clear.
 
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