Siren noise on initial acceleration...

[Carps]

OK. I have just spent about 3 hours browsing the AudiWorld Forum about siren noises. And now I am none the wiser.

A little history - I am due to pick up my S4 next week. When I test drove it, on initial light acceleration there was a faint siren noise which made me look in my mirrors, and even the missus noticed it and was looking behind. Stereo was off, and the noise was faint. It was only noticable on the initial acceleration.

Is this normal ? The car is stock with a full Audi history and has done 40,000 miles.

Any recommendations on a course of action ? Or is
It has been suggested to get a dealer do a pre-warranty extension check.

Thanks in advance

[TurkS4]

Hi Carp,

It could be one of two things...

Turbos spooling....usually around 2-2.5k revs...normal

siren sound through the centre console air vents....this is usual at very low revs and is to do with the climate control and not the turbos....normal

I have both on my car and it has done only 19k miles. I was concerned the same as you, however, reading through various posts on other boards it is normal for our cars to makes these sounds.

i hope this helps to put your mind at rest.
[img]images/graemlins/033102bigblink_1_prv.gif[/img]

[Dippy]

Does it only happen with the car cold? If so, and considering that it's only feint, then it's nothing to worry about.

During the cold spell this winter my car could make that sort of noise, but only whilst it was very cold. As soon as it was even slightly warm there was no noise. Having said that I drove the car off-boost whilst it was cold and managed to avoid making the sound at all.

The greatest wear to the turbos happens when the oil is cold and is not doing it's job as well as when it's warm.

If the car is less than 3 years old then you should still have some warranty left. Either way you should get an extended warranty as you don't know how careful the previous owner has been.

Also check if the car has been on fixed or variable services. With fixed interval the Audi dealer is allowed to use cheaper non- or semi-synthetic oil. Such oil is not as kind to the turbos as fully-synthetic (which is required for AVS).

Cheers,
Dave

[DavidT]

As per post in the other thread, I'd say have the car inspected.

I would do so on a car of this value even if I did not suspect there was a problem. They are expensive cars and very expensive to repair, so the inspection cost is easily justified.

David

[jeffw]

Your always going to get a faint turbo spool-up noise, I've had it on all 3 turbo cars I had (S4, Impreza, 944 Turbo) and I haven't lost a turbo yet. Anything that spins at 100,000 revs (or more) is allowed to make a slight noise !

[Joshie]

I have experienced this with the original KO3 turbos which had covered 50K miles. Time for replacement in that case I'm afraid.

In the second case I had a set of KO4's fail.

Even if the whistle is faint I would say that in my experience they are on their way out - perhaps not in danger of imminent failure but lets just say their life will be shorter. This is bad news bbecause chances are your warrantly will have expired when they are required to be replaced.

Cost £2500-£3500 depending if reconditioned turbos are used ar not. A bill you can do without.

Get an independent assessement from a specialist like AmD before buying.

[Carps]

My mind was almost at rest then [img]images/graemlins/wink.gif[/img]
At 11:00 I had decided to cancel the deal.
By 16:00 I was back on it having read some positive posts here.
Now I don't know what to do again [img]images/graemlins/frown.gif[/img]

I drove another S4 today which did not look like it had been very well loved. It didn't make the noise, but then it was warm already.
More facts on my potential purchase:
It has just had its' 40K service
It is 5 months out of warranty.
It will cost £860 for an Audi warranty (+£85 inspection)
It is the best S4 condition wise that I have seen

I am now thinking I insist on the dealer warranty inspection, and make a point about the noise to see what they say.

[Mik]

I have a similar issue on my S4 Avant... [img]images/graemlins/s4anogaro.gif[/img]

Loud-ish turbo spooling....usually around 2-2.5k revs...thing is that it has gone gradually louder over the last 5k miles or so (car is just getting 60k). I also have a rattle from the exhaust/turbo area - which I have been told either is the heat shield ...or...(Audi dealers gave me several stories....I forget them all)
Anyways, had it with the dealers - off to AMD to have 60k service and proper diagnose later this month. Hope its not too bad....car seems ok except for the noise.

[TurkS4]

I love the sound of my turbos spooling in the morning [img]images/graemlins/grin.gif[/img]

[Mik]

[img]images/graemlins/confused.gif[/img] Not if it was as loud as mine...you wouldnt..

[DavidT]

Jeff is right, all turbos make a turbine noise when they spool up regardless of whether they are new or old. If the turbo(s) are healthy the noise is not too loud, you would not be able to hear it with the windows up and music playing quietly, though you would with the music off.

When the turbine wheels are damaged, they distort the incoming airflow / outgoing exhaust more, hence the increase in noise.

If you can, get the car started from cold and look for blue smoke.

If the seller agrees to the inspection, you can assume he/she does not think the car has faults. If its a no, maybe you should look for another car.

I would expect the dealer inspection to find any faults the car has. Would there be any redress in the warranty or with the dealer if a fault is identified after you purchase the car ? worth checking the terms of the inspection / warranty.

I would recommend warranty. It's expensive, but I justified it because it only equates to 10 hours Audi labour in a year and a simple fault will approach that figure. Turbo's are around £3k fitted I think.


Best of luck.

David

[Riz_RS4]

If you think your turbo is loud im sure this one is louder and its got sirens too [img]images/graemlins/roflmao.gif[/img]

[Joshie]

If you're going for an extended warranty then for C£900 this should give you peace of mind, depending on your mileage. Best to talk to the dealer and see what he says.

I agree with one or two here that a spoling turbo can sound quite nice although the trouble is that they tend to get louder as time goes by. If the car is warm and the windows are up I would say that they shouldn't be audible inside the car though.

Alternatively, keep looking for the right car - I know S4's are rare though but good examples come along from time to time.

[Dippy]

Now I don't know what to do again [img]images/graemlins/frown.gif[/img]

I drove another S4 today which did not look like it had been very well loved. It didn't make the noise, but then it was warm already.
More facts on my potential purchase:
It has just had its' 40K service
It is 5 months out of warranty.
It will cost £860 for an Audi warranty (+£85 inspection)
It is the best S4 condition wise that I have seen

If its the best you've seen then buy it and get the extended warranty. Maybe its £900 more than you wanted to spend, but it's clearly the car you want and you also want peace of mind.

For those who think that the noise is OK, please re-read Joshie's posts. He's had two sets of turbos fail and he knows what he's talking about!!!