lgashi

What do you mean ? Im afraid I didnt understand you

Thank you for your response

2turbos4rings

I think I hear the noise you’re talking about when you go under the car. From the top all I hear is the combustion clatter, valve train noise and injectors. How fastidious are you about the quality of diesel that you use? How is your performance? Is the sound low or high pitched in person?

It could be your injectors, how many miles (or kms). Could be injector nailing if it’s high pitched. Your mechanic can check them with load, volume or individual feedback values and check them agains Audi spec.

Its really really hard to hear things with YouTube videos from phones or other low quality microphones. Your best bet is someone in person.

Also a note about gas V8 engines since it was brought up- the engine is not removed for a D4 cam tensioner job.

A8L_New_England

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I'm thinking that it could be a botched or incomplete chain job, where (for instance) they might have changed the chain and missed changing a faulty tensioner or idler.
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lgashi

Thank you for your response

You can get more sense of sound here, definitly its low pitch in inside and outside like "helicopter noise u hear when one is flying above you" - https://drive.google.com/file/d/1lbl...ew?usp=sharing

Im planning to use different gas station now just to check if diesel has any impact on this

Car right now have around 250.000kms performance ifs great so I didnt notice any drawback there

Didnt understand that part you sre talking about V8, fyi this car has V6 engine

lgashi

That could be an option too, there is no problem opening engine again the main thing is that mechanic have no idea what could be the problem and what can he fixes..

2turbos4rings

The V8 comment was only in response to Striker’s comment

I see what you mean. Would you mind taking another one like that and just gently revving it a little? Not too much. But try it a couple different ways, rev to like 1,100 or 1,200 rpm and hold it for a moment and let it slowly come back to idle and then rev it gently but quickly. I want to hear how the tone changes as RPM climbs. I’m still feeling like injectors. It sounds like diesel combustion but modified/louder. Like preignition or something else not causing a full burn/proper combustion. Just a theory so far..

From these videos alone I would rule out chain tensioners, the chain rolling on the head/valve cover is more constant and higher pitched than what we hear in the car

lgashi

Thanks for the detailed response really appreciate it

Here is another video I tried to make it from another perspective that can help u hear better what is going on, so the weird noise starts from second 17 : https://drive.google.com/file/d/1Oon...ew?usp=sharing

We are thinking that could be injectors too, one thing to mention is that in person it feels that this noise is coming from bottom of engine somewhere, maybe thats stupid idea, but it feels like this

Thank you again !