Hairdryer/vacuum cleaner like sound from under car and in cabin

[HJames]

Hi guys, I'm new here and finding it hard to find the right place to post, so forgive me if this is in the wrong place! Was hoping someone could help me? I have a 2009 3.0 z4. My second one and I love it! Only issue is when you're sitting in the cab stationary and if you listen under the car (from behind and the sides) there is a strange sort of buzzing. Almost sounds like a hairdryer or vacuum cleaner!!

It deffo isn't the radiator fan etc. It sounds like a fan is whirring or sucking in air like a vacuum cleaner - any thoughts??


J

[MarcoZandrini]

You ran over a hair stylist? /s

Could be a vacuum leak. How does the engine idle? Does the noise change-volume or frequency-as the engine speed changes? Record the sound with your smartphone and post RF video/sound on YouTube. Post the link.

[White94RX]

I bet you're hearing the fuel pump.

[BimmerBreaker]

Or SAP if it does it at startup

[White94RX]

2009 won't have a secondary air pump. Unless its a SULEV, but I think SULEV was 3 series only.

[BimmerBreaker]

2009 won't have a secondary air pump. Unless its a SULEV, but I think SULEV was 3 series only.

I thought all E85's had them, and based on OP's location (UK) the 2009 could be what we know as a 2008, so I was still thinking E85.

Maybe even later year E85's didn't get em though, I know some engines did and some didn't.

[White94RX]

I was assuming E89. I've heard loud fuel pumps on both models. It's right behind the passenger seat, and some are louder than others. I've replaced a few for complaints of noise.