Dr.S4

Ever since yesterday i've been hearing an abnormal whining sound from the turbos...it seems its coming from the passenger side. This sound is not the normal turbo whistle which i can still hear normally. The whining sound is much louder. Anyone have any ideas as to what it may be???
Performance is the same otherwise.
Thanks!

BaysideRS4

Let me guess, is it more audible in the 2800-3100 rpm range and with the windows up?

Dr.S4

Thanks!

ÅllroÅd :DFW

it's the turbos. The 'siren' sound. Delaers will say it's normal - A few early complainers had their turbos replaced, but many S4s develop them and it's part of the quirkiness of the motor.

BaysideRS4

I have 2 theories:

1) turbo bearings
2) leaking charged air

I lean towards number 1, but the turbos spool well before the sound is audible (1800 rpms give or take), so that has made my paranoia shift to number 2. OTOH, it may only be audible at certain rpms.

I'm pretty good at discerning sounds. And this one comes on all of a sudden at around 2800. If it were directly tied to the rotation of the turbo, there would be more of a gradual, audible entrance to the human range of sound.

It's very strange. At times it is only audible when oil temp is cold (below 215F). Other times it is audible when fully hot.

The only consistency I have noticed is that it will be present when the engine is hot if I, for whatever reason, delve into the boost before the engine is fully warmed up. In that case, it stays no matter how hot the car. I dunno, maybe it's Audi's built in stay out of the boost signal.

Zaphod//TMK:Indukted

Is it most prominent when the car is cold? If so and the car is fairly new, then don't worry.

For some reason when the motor has been broken in the turbos develop a sounds described as the "siren" sound. This is usually a normal thing and nothing to worry about. Go take a listen to older turbo cars, especially ones with performance mods. My buddy's VR-4 shrieks like a banshee who just got a piercing! But that is ok.
Pay attention if the sound gets increasingly loud. there is a point where it can become a problem and is indicative of something grinding or spinning incorrectly. But if it stays low and decreases as the engine heats up, then don't worry.

z | b

BluLytNin

...who needs BOV's when you have turbos that sound like his =^)

BaysideRS4

Z, does your car have this sound? Mine mostly stays, to a lesser degree, when warmed up

Zaphod//TMK:Indukted

within the last month or so. Same deal, the sound stays when warmed up but to a much lesser extent. Every S4 I have been in that has some mileage on it makes that sound. Some are REALLY loud.

If it makes you paranoid, I understand. It honestly makes me nervous sometimes. My advice, get a boost gauge. That's really the only way to monitor the condition of your turbos. If you start to notice the sound getting louder, or different, just see what kind of boost you are running. If you notice the boost is down, you may have a problem. Using the VAG to check is not always the best solution because you are looking at what the ECU sees, not what pressure is actually in the lines. A mechanical boost gauge being supplied by the vacuum line off the fuel pressure regulator is telling you exactly what is happening with the boost.

z | b

TommyS401`

Same sound here. its like a whining/winding noise, like a low whistle