New, odd noise
 

Hello all

Was parked next to a wall today with the window down and noticed an odd, warbling, fluctuating, intermittent, quick noise. It isn't related to the power steering and doesn't seem rev related.

Sorry for the poor video quality but you can hear it, (ignore the ticking, I think that is the fuel lines, right???). When I put the phone into the wheel arch, I fortuitously manage to catch it instantly stopping, so it is something that switches off.....
It is only audible on the near side.

Any suggestions/ comments etc greatly received. I don't have vagcom so will need to book it in somewhere to see if a code had been thrown up. Car is driving normally.

Your air suspension compressor sits in the front of the NS wheel arch and it will be intermittent. You could test by lowering and raising the suspension while listening.

Thanks for the advice, I checked and it doesn't seem to be created by the air compressor, although .........does that system used 'stored air' and doesn't always run the compressor when adjusting height?
Is there anything that can be done to a noisy compressor if is that, sprayed with WD40 for example?!

The noise does also seem to be rev related. After further exploration it sounds like it is coming from the N/S rear of the engine. Not audible from the inside unless the window is open.
It stops after 5-10 secs when pausing at traffic lights etc.
Are there any secondary pumps/systems it could be in that area? Oil cooler or pump for example. Just had a new V belt and thought it could have been that at first but obviously it's at the front and running all the time.
I am very confused.

Just a quick update.
I still haven't figured out what the sound/issue is but have probably eliminated the suspension pump. The sound is coming from the very back of the engine, the right (N/S) bank only.

For those of you who have experienced BMW Vanos 'buzz', it reminds me of that. Very intermittent and quite hard to induce but results in an annoying sound! Worse immediately upon start up, hot or cold.

Having looked at the V10 engine tech doc I am thinking it could be chain tensioner related.... My AC also refuses to switch on, could they be related I wonder.

Anyway my quest continues....until the inevitable trip to a spanner expert.

Another update.

As always I thought I would go back to basics, start with what I know so I checked the oil level. Alarmingly it was so low it wasn't even touching the dipstick! (Problem 1).

It took 1.6 litres. Since then and a bit of driving the buzzing has largely stopped. I wonder if the noise is/was the oil separator struggling to operate? I believe it is at the back N/S of the engine? (Problem 2).

I also established that the very bottom of the wheel arch liner has not been reattached after recent suspension work and was rubbing on the wheel, that was creating some noise and feel through the steering wheel as well. (Problem 3).

I'll keep going!

Oh dear. At least you’re on to the problems. Hate stuff like this, I already have overly sensitive hearing and cannot let any little noise go unnoticed!

Completely agree, 'noises' are a shocker arn't they! Trying to get passengers to be quiet whilst your ears hunt for the unusual sound they just heard, LOL!

Exactly this^

Usually these noises precisely coincide with the Mrs telling me something, repeatedly. Something she feels so important she MUST tell me twice, having already told me.....

I had an RS Clio 172 for 6 years, and it was such fun, but the catalogue of squeaks and rattles were less fun. I actually had the wife, gf at the time, drive me down the M62 at 95 (kph) while I crawled around the boot with the rear seats down to track down the noise that had been annoying the hell out of me during my commute.

So it looks more and more like the chain tensioner has worn sufficiently to allow the chain to clatter. The noise is getting more frequent.

There has been a suggestion of using a thicker oil to lesson the noise, increase oil pressure etc until I get the work done. Any comments on that? If positive which oil?

Bloody hell, engine out job I suppose..........

Chain tensioners were done on my D3 4.2 in February this year along with the cam belt and all tensioners etc - the Audi parts prices alone for that whole job can come to about £1200 :eek: but were got down to about £650 by using OEM manufacturer parts sourced mainly via ebay. The tensioners was not a fun job - made worse by the LPG system all over the top of my engine - but was do-able without the engine out although some of the cam top caps had to be loosened on one side to get to the rear tensioner. The front one on the other side was somewhat easier. the old tensioners at approx 150K miles were nicely grooved but still had a little life left in them but would not in my opinion have got to the third cam belt change before breaking or causing damage by the chains to the metal they were sitting on. +++