Vacuum non-return valve suspected. What are the implications?

[aleksa]

Hi all,

Our Golf MK3 makes a bit of noise (sort of trumpet sound) on this ?non-return? valve, please have a look at the video below.

https://www.youtube.com/watch?v=KMO5...e_gdata_player
is this typical, would you reckon replacing the hoses and/or valve might fix the issue?
How urgent is it to fix, what may be implications?
How much it might cost?

Cheers,

Alex