Vacumm Air Leak

[HAWKS]

Hello.
Ive noticed when driving and i go to change gear,i hear a queit hisss(if windows are down).Its like a quieter recurc dump valve sound.
Ive checked all vacumm hoses an cut off 1 inch to all connections to rule out leaks.
Ive just ordered new vacumm hoses to replace them all.(green)
The car drives well,mpg good.
I dont have VCDS.
Anything else worth checking out.
Cheers.
Graham.

[Alan02]

Could be a small hole in an Intercooler hose?

[HAWKS]

Update.
All Vac hoses have been changed including the pipe to the Vac reservoir.Ive tightened the intercooler hoses too.
Its still making the noise..
Would a damaged/split intercooler only make this noise when changing gear or would you here it all the time.
It doesnt make any hissing noise when you rev the engine,just when its under load when letting off to change gear.
Anything else to check.
Thanks for any help.
Graham.

[HAWKS]

Still doind it...
Would a scan throw any codes..

[HAWKS]

Before i pay out beer tokens for a scan.Would this kind of fault produce a code??

[micheal balbrig]

Could it be exhaust leak at flexi pipe when engine moves, one member had this problem but it was accompanied by sooty smell.

[HAWKS]

Deffo not exhaust leak.
Its like a silent dump valve sound hiss when letting off the gas to change gear.Car runs good,pulls well(i think).It didnt used to be there an now it is.

[micheal balbrig]

It seems another thing that may produce a hiss sound is the wastegate valve !!