Hissing noise when engine switched off

[Erfan]

With the help of this forum I am learning a bit more about my W210

Is it normal to have a hissing sound come from the 2 vacuum pipes that go into what I believe is the egr vacuum control valve? The noise lasts about 10 seconds after switching engine off.

I've not experienced this on other cars I have owned.

Thanks

 

[Mickybo]

I get the same from mine, it comes from the small filter like widget on the bottom of the egr solenoid, I just take no notice of it

 

[Harlowcabbie]

I believe it's the vacuum bleeding off from the system, perfectly Normal

 

[Erfan]

Thanks!