Volvo Repair: engine sounds like air is leaking, flame trap, funky noise

Question
I have a 2005 Volvo S40 AWD T5. The problem just started on Sunday the 2nd when I went to San Francisco. The car is running great but once I came back to Sacramento a weird noise coming from the engine like something is squealing. I check all the hoses and I noticed that the hose which is located close to the oil filter. It looks like ventilation hose from the oil filter compartment to the head of the engine was completely busted. I decided do not move my car and get the part. I got the part with the Dealer. But after the installation was completed the car was still making the funky noise. I opened the oil cap and it sound like air is been released from the engine and any single time when I put back the the cap the noise comes back again.
Not Check engine light comes out at all. No codes, nothing; RPM are a little bit higher almost unnoticed it.Engine runs great.

What it could be the problem?

Answer
Ostap, good question.  If this car has under 50,000 miles then its still under warranty.  There may be a clogged flame trap box.  Its hard to say without inspecting the car.  I would find out if its still under warranty and make an appointment with the dealer.  Roger


Ostap, Flame trap box = oil trap box just like I suggested. I never had to replace one on a S40. I know how those things work.  I appreciate the explanation but it was not neccessary.  Im glad you found the problem.  Take care.  Roger