2004 Mazda 6 PCV Valve Noise
My 2004 Mazda 6 is making a strange whistling and hooting sound coming from the front of the car. It runs fine, but the noise is a bit too much. Have you seen this?”
Yes, I have seen that. There’s a pollution valve on the engine called the PCV valve. It has a hose that connects to one end of the valve which has vacuum pressure from the intake manifold. This hose is rather cheaply made and they often collapses, making strange hooting and whistling sounds. It’s pretty hard to access this hose without removing the intake manifold (which is pretty expensive.) But I’ve done it without taking the manifold off. I just used a bit of elbow grease, some long curved needle nosed pliars, and a bit of selective cursing to get it done.