Hissing / blowing noise under hard acceleration, 1.9 TDi

[miff]

Hi guys,

I recently changed cars to a ~3 year old / ~40k miles Altea XL with the 1.9 TDi (105).

A few days ago I noticed a strange hissing / blowing noise under hard acceleration, sounding like it is coming from the rear of the car. It's not that loud, and I only noticed it while driving with the load cover open (which makes me think the noise is coming from under the boot somewhere).

The noise starts a second or so after the turbo kicks in. It's very quiet at first but becomes louder as the revs build up (I guess, as more exhaust gas is flowing). It's not a smooth noise, the best way I can think to describe it is like the noise you get from an upstairs water pipe when a tap is running.

Fuel economy seems to be okay, and power delivery seems to be okay (although it's hard to judge, having just downgraded from a 2.0 TDi 140 in my previous Leon...)

Any ideas what it could indicate? My guess is, some part of the exhaust system, but I'm no mechanic and searching for exhaust noises on Google isn't easy TIA.

 

[Viking]

Most likely is a loose or split boost pipe in the engine bay.

 

[ryanmorel]

Air blowing noise in engine bay

Hello I'm just wondering if you found anything out about the air blowing in the engine bay sound. I'm having the exact same issue with my 02 Volkswagen golf tdi also.

 

[cjfarrar]

Could be one of a few things:

Crack in exhaust pipe
Damaged cat (if fitted)
Loose or split boost pipe.

I would suggest getting a friend to help, if it's front wheel drive jack both front wheels up so car clear of ground, put car in gear and drive as you normally would whist either you or friend checks the engine bay and exhaust for the noise.

Be warned though, make sure you secure the car on stands if doing this and put bricks behind rear wheels.

Sounds daft but it works