Whistling sound when accellerating in 2004 Volvo S80

user1337 · Post by **user1337** » 24 May 2025, 03:02

Hello everyone,

I just bought a used 2004 Volvo S80 with a 2.4L petrol engine with 180 000 km/112 000 miles on the odometer. The car makes a whistling sound when I am accelerating. The harder I push the pedal the louder it gets, and it goes away if I release the gas and let the car coast. Fuel consumption also seems unusually high at 16,8L/100 km / 14 miles per gallon, according to the onboard computer. The car also idles high at a bit under 2000 RPM. I’m suspecting a vacuum leak but it is just a theory. Does anyone else have any good suggestion to what it could be? And is it expensive to fix?

Cees Klumper · Post by **Cees Klumper** » 13 Jul 2025, 10:11

Sounds like a turbo/boost leak, check all the big hoses that route from the turbo to the intercooler back to the intake manifold. Chances are one of them popped off or has a leak.

user1337 · Post by **user1337** » 23 Nov 2025, 12:32

So I still haven’t solved this, but the issues with high fuel consumption and idling have been sorted. The car does not have a turbo, but a local mechanic said that the sound sounded like a turbo spooling up. I have attached a video of the sound.

Post by **scot850** » 23 Nov 2025, 17:16

Sorry, even on max volume I can't hear anything other than the normal engine noise of a non-turbo engine.

Your fuel consumption could be many things. Do you have any service history for the car of repairs and servicing that has been done recently?

Neil.

Cees Klumper · Post by **Cees Klumper** » 04 Jan 2026, 13:17

I do hear the turbo sound. If the mechanic wasn't alarmed, and the car performs well, I would probably just live with it.

Post by **BlackBart** » 04 Jan 2026, 13:49

It sure sounds like an air leak somewhere, but you say you’ve fixed the idle problem? Have you followed all the little vacuum lines to their ends to check for cracks?

user1337 · Post by **user1337** » 23 Jan 2026, 03:25

I just had the car to another mechanic who looked at it, and that brought me a lot closer to the cause of the issue. The noise gets a lot stronger if I have something connected to the 12V connection on the dashboard, such as my phone charger and DAB adapter. If I unplug those the sound is basically gone I think, although I can sometimes hear something faint when accellerating hard at low speeds. The mechanic said it was because the power produced increases when accelerating and that somehow causes the sound. It could potentially be from the 12V to USB adapter itself.

The car is a 2.4L non-turbo, although the sound does sound a lot like a turbo spinning up.

Hendoo · Post by **Hendoo** » 03 Feb 2026, 20:08

Any feeling for where the sound is coming from?

Is it coming from the engine? Or elsewhere?

My S80 is non-turbo, but when the in-tank fuel pump was giving up it made a faint whistling sound sometimes. That was clearly coming from inside the car.

May not apply to your turbo but any info you can provide about the whistle may help.