So i have noticed over the last week or two that i have had a strange noise. When im on the accelerator, i get a whistle'ish noise, to be honest to me it sounds like suction, like a vacuum line is just freely sucking in air. It has gotten louder over the week and its starting to worry me. Once the car is up to speed and it shifts into high gear the noise seems to go away, spikes on the gas pedal result in the same sound making a blow off valve kind of noise.

Attempted recording of it:

please help, any ideas are a plus. im new to turbo's, it boosts fine and has tons of power, but i don't want the noise to do more damage over time.

 

Hi and welcome to the forum. To start, it's not boosting fine. It should be boosting 3/4 of the way into the white. It sounds to me like you have a vacuum line loose under the dash. How long have you owned the car?

 

When i give the car heavy acceleration the needle goes up to 3/4 white, and then falls a bit below then and holds.. The video was recorded under light acceleration, but i do think it has lost some boost

Ive owned the car for about a year, but it has only been daily driven for about 3 months. You have helped me with it before over at MVS (thank you). I took out the glove box to see if there was any lines i could see loose or hear a loudness difference with it open / shut, but i cant find anything

 

there is nothing inside the care that has to do with vacuum or boost other than one black plastic line on the drivers side that runs the boost gauge. So dont bother searching.

Are you sure its boosting ok? I am agreeing with Robert that does not seem to accelerate like it should. To be honest I did not hear the sound you described. You should go check the vacuum tree behind the throttle body for any fittings that have popped off and the vacuum/boost lines that run to the turbo and turbo control valve. Also look at the rubber hoses after the turbo for tares. Common weak area is the underside of the hose that attaches to the throttle body where the idle control line splits off.

 

I have checked around the vacuum tree and don't see anything that has popped off or any obvious line damage. I did replace the one hose going from the waste gate to the turbo control valve, but i did not replace the other ones that runs back from the turbo along the side of the engine and plugs in near the vacuum tree area. Could you please elaborate a little on the common weak point? I'm not super car savvy i just know enough to get myself into trouble..

p.s. is it worth checking the vacuum line that runs the boost gauge? I really don't want to take the dash top off again (had it off / not secured for months while trying to fix my gauge cluster issues)
Thanks for the reply

 

I agree w/boxpin; something on the pressure side of your turbo hosing is likely leaking. The "pressure side" is everything from rubber hose at top of cold side of turbo to your throttle body. In between is the intercooler and all the hoses/pipes (roughly 2" in diameter) in between. If this doesn't make any sense to you then you probably should take it to a good indy volvo shop.

Nothing in the cabin as far as vacuum lines except the thin one that connects to the instrument cluster, but that's OK since your boost gauge moves; if it was disconnected the boost gauge would stay vertical all the time.