Possible boost leak? - Hiss / Air escaping when turbo spools up (2.0 TDI 170)

[The_life_pursuit]

Need some help please. I have a 2007 A3 2.0 TDI 170, which has covered 78,000 miles. The car has just developed a hissing / air escaping noise in 3rd, 4th and 5th gear when accelerating. The noise occurs between 1500rpm and 2000rpm only. I believe it's when the turbo initially spools up under load.

I took the car to Audi who advised that the intake manifold was the cause and needed replacing, which they did. I picked the car up and the same noise can still be heard, so it went back. Just had a call from the tech who advised they have pressurised the system, and cannot find any leaks.

(NB - the noise is not the usual 'whine' you get from the turbo, more like the sound you get from a punctured tyre when the pressurised air is escaping)

Any advice would be appreciated as I suspect Audi will return the car with it still exhibiting the same symptoms.

 

[Sevv]

check the inlet mani hoses and clamps, along with the discharge pipe, and inlet /outlet to the FMIC , ive seen a few golf tdi coming in having that issue, might wanna check the brake booster too

 

[davc]

Been there before with the same problem, turned out to be the IC exit pipe.

 

[The_life_pursuit]

Been there before with the same problem, turned out to be the IC exit pipe.

Cheers Sevv and davc for the advice. Due to pick the car up shortly. Audi have advised they have tested the system with 1 bar of pressure, and found no leaks, and done a visual inspection and found nothing. Will have to wait and see....

 

[dannyjna]

Mine was the pipe behind the front bumper underneath, think the mrs clipped it on a kerb just clipped back in mines only a 140 tho