Vacuum leak on 115bhp azm passat

[smithy602179]

HI GUYS .
i have a hissing somewhere behind and below the engine on nearside (under the water reservoir tank ), can be faintly heard while engine running , and if accelerator pressed and released its louder , presume its a leak but checked pipes but none found ,but not dismantled them off car to inspect , anyone have an idea which pipe could be the most likely to have failed...:confused:

[vwdocdave]

Hi, couple of things. If your car has air con it could be this making a noise. If gas in system in low can make hissin noises. the other thing would be a boost presure leak, or vacuume leak, there are plenty of pipes which run along the boost pipe. Hope this helps.

[Entropy]

You can test for a vacuum leak by using either propane or throttle cleaner but make sure if you use the latter, the engine is cold. Here's a useful video from EricTheCarGuy: http://www.youtube.com/watch?v=9CPqbaSgcok&feature=related

[Sam]

AZM is an NA engine so no turbo/boost.

The pipe which tends to split is over the back of the engine (between engine and firewall) and runs the width of the car.

Mix up a bucket of soapy water and cover the pipes you suspect to be leaking - watch for bubbles.