Audi Repair: loud noise when you start, audi a6, air leak

Question
i have an 98 Audi A6 when you start it after it been off for about an hour or so you could this loud noise coming from the right front side like its charging and you could feel air coming out too. is this a big problem and i could i fix it. thank you

Answer
hello
This sounds like a secondary air system, it's used to warm up cats on cold starts. If it's very noisy - you may need new pump. Try to find out where the air leak is , this pump is connected to engine combi valves and it will set MIL light on if there is a leak.
If there is no leak, noise is not a big problem, my S4 it's making this noise for last year .
good luck                pltech