V6 TDi whining noise - sounds like a supercharger

[JSRed]

Of course it might not be the fan - it might be trying to complete a DPF regen... you get a sound of a fan running and lots of hot air coming out from under the front of the car.

You can kinda tell if it's trying to do a regen because it seems to also adjust its gear shift selection - holds lower gears to keep engine temp up. If you have the exhaust in dynamic mode it's noticeable that the car seems noisier (akin to sport mode). It's subtle but once you understand the feel of the car you will start to notice and will be able to tell when a DPF regen is under way - I now routinely take the car for a 15 minute drive in sport mode to get the regen to complete.

Ive noticed it has definitely tried to do a regen when I've parked up - as you say, hot and a bit smelly with the fan running. Strange as there is a sticker in the front door telling you that if a light comes on (it shows the icon) then it's doing a regen and not to turn it off. I've never seen it come on. Previous diseasals I've had rarely did a regen because I always drive hard so they never seemed to get clogged up enough. Maybe because this is a post diesel-gate car, VAG have tinkered with it a bit more. Who knows.

Ref the whining, I suppose it could be the turbo, driving it again and listening it definitely kicks in around 2,500 rpm all the way to around 5,000 and it shifts up. Maybe the turbos are loosening up a bit and it's just the noise it makes. It doesn't sound awful at all, it makes it sound even better really - a bit like a WRC car

Anyway, cheers for all the helpful advice


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[jmfjohn]

Did you ever find out the source of the noise?

[JSRed]

Did you ever find out the source of the noise?

Not really. It's kind of a more distinct turbo whistle now. It's definitely a bit whiney still but i do think it's the turbo.

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[jmfjohn]

Hmm I'll take the car in on Monday to have it checked. I drove two other sq5s TDI before and none had this whine so I'm pretty sure it's not normal.

[A6S]

It could be turbo whine(not good sign) or possible a boost leak somewhere. If it’s a small boost leak the turbo will just keep boosting till the required boost is achieved which can over work the turbo giving a whine.

[jmfjohn]

I'm pretty confident it's not a boost leak as it remains constant while at constant speed when i guess only minimal boost is requested from the turbo. I also have the sound while engine breaking...

What's turbo whine?