S6 Rattle - timing chain going?

A6 All/ S6 All
#10

It has been happening on every start when the car has been left about 8 hours. I went to film it this morning and there was no noise at all. It’s typical when diagnosing things from noises!!!

If something goes wrong it’s no big problem, I just don’t want my timing to go and smash the engine up. Anything else if probably not a big issue. I’ll mention the SAI to the mechanic when I go back for a check up next week.

Does anyone else have a rougher engine for a minute on startup before it settles down?

#11

Do you have a Milltek exhaust by any chance?

My S6 has similar symptoms. It seems to happen whenever the engine is cold, and goes away once it’s warm. Anything over about 3k RPM I hear (what sounds to me like) an exhaust system rattle. I had assumed there was something loose in my exhaust, but thermal expansion causes it to go away after a while. I have not yet identified the exact source of the sound.

#12

It’s not really rough, as in shaky, but it can by a little “jumpy” for the 10 or 20 seconds after a cold startup. If I put the car in Drive or Reverse immediately after starting the engine cold, the car will feel lurchy. During that time, and then for another 40 seconds or so after that, the exhaust is much louder than normal and the idle is about 1k rpm. After 60 seconds of that, everything calms back down to normal (Some believe the ECU does this intentionally to warm up the exhaust system), although the rattle I described earlier could remain for up to another 2 or 3 minutes.

#13

What your mentioning is the SAI system. The ECU is allowing the SAI system to push extra air into the exhaust to warm up the cats so they get up to operational temp quicker. The SAI system only works for the first min or so. It will make for a louder cold start and rough conditions until it turns off

#14

Mine does the EXACT same thing. Thought it could be a slight miss when cold due to carbon buildup or something. Been looking into options for carbon clean.

#15

Excellent. The rattle does sound like it’s from the exhaust area, but it depends on where you are stood in relation to the car. I’m satisfied it’s not the timing chain now after listening carefully to some cold starts. I didn’t even know about the SAI system; the same way I never knew cars had crankcase breather systems until I got the S6 (and it failed).

Thanks for this guys, let’s me enjoy the car without worrying about start-up noises.

#16

There’s really only one option for the carbon clean as far as I can tell. I can’t imagine there are any realistic shortcuts to removing the manifold and getting scrubbing. Just did mine however and it makes no difference to the 60 second rough / lumpy startup.

#17

carbon is only removed by getting in there and taking it off. To do that correctly you need to pull the intake manifold.

#18

I’ve got the same problem–especially if I haven’t driven the car for weeks. (115K miles)

But I’d like to know if it’s just an oil circulation issue, or a reason to take the engine out and do a timing chain service. (My mechanic thinks my oil leak is coming from the cam gaskets, but he can’t be sure unless he takes the engine out.)

I haven’t found any video to hear what chain rattle is supposed to sound like. But here’s a video of mine at startup:

Lets play "Fix it or Scrap it"
#19

Slightly hard to tell from that. But to me it sounds like it’s not rattle.

A few things to keep in mind. If you let the motor sit long enough the lifters can bleed down. There is a chunk of time where there is no oil so that can also cause ticking.

#20

I think that probably the case because once the oil starts to flow the engine seems to run smoothly. But I’d still like to know about timing chain rattle. The car is 13y old @ 115K miles. If I’m going to have to take the engine out, I’d rather do it now when the labor cost is a fraction of my next post.

Has anyone found a video that demonstrates what it sounds like when your timing chain is about to go off the rails?

#21

I’ll see if I can get CV to post a video of one of his cars he bough that had a NASTY chain rattle. I listened again and I don’t think your getting that.

But if you have cheap labor. I would have the motor pulled out just to get the cats out. Sooner or later they can cause issues. And with the cats out there is less strain on the motor and a taste more power.

#22

Someone has told me, that the notorious chain “rattle” on the v8 FSI is a total misnomer. Apparently chain problems in that case sound like someone is banging a hammer on the block.

I’m guessing the ticking is coming from the cam adjusters and noisy injectors doing their… doings as normal, might be slightly louder for a moment at startup and cold starts.

I have an exhaust leak, and for the first 60sec my s6 sounds like a Harley, because the SAI pump is pushing extra air into the exhaust to warm up the cats. So that is one thing to take into account. It also makes for a rough idle, so it’s good to wait a few minutes, before driving off.

Also, the engine is designed to run 5w-30. So anything thicker, will probably make it more noisy, that thick tar won’t flow as freely in the tiny passages they designed for 5w-30 oil.

#23

5w30?

Spec is 5w40.

#24

Mine has been in Long-Life service from new (now at 337800km/211,125mi) and VW 504 00 is stated in the cars German manual.

Looking here: https://www.audiusa.com/content/dam/audiusa/Documents/Audi-1997-2012-Technical-Service-Bulletin.pdf

The VW oem oil, as well as other recommended 504 oils, are 5w-30… :confused:

Audi service recommends to use Castrol edge 5w-30 for added protection, over the oem G 052195 5w-30.

I put in the oem oil for now, will need to flush once more (because last oil was crappy and in for over 24000km/15,000mi). After that I’ll stick to 5w-30 Castrol Edge and 10000km/6250mi change interval.

#25

Wrong oil standard. You should be looking at the VW 502 standard.

#26

Owner’s manual says:
LongLife-service:
VW 503 00
VW 504 00

Static service interval:
VW 502 00
VW 503 00
VW 504 00

Audi service plan says:
VW 503 00
VW 503 01
VW 504 00

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#27

What do you use to flush engine oil?

#28

Thanks for posting the above photos. Exactly as in my manual. Maybe they recommended 502 in U.S. because of availability? Price? In Finland temps are way below freezing for months, so I usually use 0w-** if possible.

I have successfully used forte brand engine flush, followed by a really short oilchange interval. in a really dirty old BMW m30 engine. But I might have been lucky and doubt it’s merely a bottle of overpriced gasoline…

In a modern engine I only flush by running a fresh batch of the recommended oil for a very short time. ~1500km/800mi…

#29

I just ran liqui moly’s flush I’ve never used liqui moly anything before but I’m going to do a full oil change with the green bottles and want to see what that does for it. I was going to change the oil again at 1500 mi and see how it looks then.