What happens at 2500rpm in the C5 S6????

[Dan95x]

Ok - I appreciate that a lot of things happen at 2.5K revs in an S6 - I will be a little more specific......

I have a strange noise, almost like a rattle, or repeated tick, that is severely impairing my ability to enjoy the V8 noise of my S6, however it only occurs from 2.5k onwards as you accelerate. I don't think it is something loose etc that happens to rattle with harmonic oscillation at those revs, as it continues then throughout the rest of the rev range

My first thought as it seems rev specific was that it could be something to do with the Variable inlet manifold, but a bit of research suggests that only comes into play at 4K revs???

It appears to be from the drivers side of the engine only, although I am not sure if that is just where I hear it from as I am sat on that side!

No signs of anything untoward on VAGCOM, and doesn't appear to affect performance, it is just thoroughly annoying and means I no longer lower my windows when going through tunnels

My thoughts so far are:

- Noisy injector(s) on drivers bank of cylinders (perhaps injectors 'open' more at +2.5K revs?)
- Exhaust Manifold leak? (although I would imagine I would hear it all the way from tickover if so)
- Fuel return solenoid?

Anyway, I am open to suggestions if anyone has had similar/know the engine well/just has any harebrained ideas.

I currently have an S6 breaker with a knackered bottom end, so have plenty of parts to swap in to diagnose/solve, so unlike normal where I would be loath to swap loads of parts due to cost, I can try pretty much anything .

Any thoughts? I swapped to an S6 from a Corrado VR6 as I thought at least it was a sensible car with a non-sensible soundtrack, but at the minute I cant enjoy it!!!!

Cheers in advance

Dan

 

[Garpemo]

Make an oil change I had some bad notice from my 3.0 and my old vr6 when I bought cheap oil.

 

[Dan95x]

Make an oil change I had some bad notice from my 3.0 and my old vr6 when I bought cheap oil.

Just had one with good quality Audi Spec oil - I had the same thought, as it does sound a bit like tappets, although again, I would expect the noise from tickover if so - In fact it is very quiet at start up from cold, so I don't think it can be tappets

 

[Garpemo]

Did you use the 0w-30 or is it 5w-40? How many miles does it have?

 

[Dan95x]

Its on just under 130K miles - Have tried both in the 2 services I have given it, as is at that sort of age/mileage where either viscosity could suit it better - Doesn't make any difference to the noise (or anything else for that matter) which - again, leading me to suspect not tappets.

It has been suggested on another forum that it could be the cam chain adjuster on that bank of cylinders - I can certainly see the logic there, so has been added to the list to try!

 

[Garpemo]

Isn't it a variable timing wheel there? I had a malfunction on mine on one bank and it went jumping one tooth after a while so I had to replace it. It costed about 500 quid.

 

[Dan95x]

Isn't it a variable timing wheel there? I had a malfunction on mine on one bank and it went jumping one tooth after a while so I had to replace it. It costed about 500 quid.

Could be, I have not been intimate with the 4.2v8 for long - as I say, I have a spare s6 sat on the drive that has a knackered bottom end, so with a bit of luck, whatever it is (as it certainly sounds top end, and to be fair also doesn't sound too terminal/scary, just irritating) I should have a spare to fit. Even if I end up trying a few of the theories, it doesn't matter cost wise, as I won't have to be buying new parts, just it don't have huge amounts of spare time at the minute either, hence wondering if anyone else had come across it.

Cheers for the suggestions so far dude, much appreciated