My 04 manual 545i has a rattling sound coming from the front right side( while sitting in the car) I'm not sure what its called but it sounds like it's coming from this silver box with two aluminum tubes going over to the compressor? I'm not sure. My buddy who works as a mechanic at a bmw dealer pulled it in and checked it out. I showed him how it really starts to sound bad at low idle while letting out the clutch. He hooked it up to the computer did a couple of checks and said I could fix it by just simply turnin up the radio...ASS!!! He said it's fine but i'm gettin nervous. It's not a steady rattle...more like a random rattle. After about 30mins of running it seems to go away at idle but when I let out the clutch and bring down the rpms u can hear it. Anyone else have this problem or have any idea what this might be??? Thanks.

 

I believe there is a TSB on the air conditioner compressoror pulley. I had a similar noise. The dealer replaced the compressor and that took care of it.

 

My '08 535i 6-speed has a rattle/ gear noise when I sit at idle with the car in nuetral and the clutch not pressed in. This sounds like it is coming from the transmission...I posted a message about it (08 535i 6-speed: gear rattle while in nuetral) about 6 months or so about it...I refer to it as "gear rattle". BMW says it's normal...that when the clutch is not pressed in, there is no pressuer on the plates (or something) and they will rattle. It's not that loud, but I never have the radio on so I hear everything in the car. BTW....I tried to just insert a link to my topic, but apparently it's too old....it's from Feb. 08.

 

thanks for the info guys but I don't think it is the compressor pully or the transmission. The sound is coming from the far left of the motor(if standing in front of the car) and the very front of the engine right under the valve cover where there is a silver attachment......is it maybe connected to the crankshaft? I don't know. But the alluminum unit has two alluminum tubes running from it to the other side in front of the motor. Oh..... and what dose TSB stand for?

 

I think TSB stands for Technical Service Bullettin. Would you believe, I actually pulled a real marble ball from the bottom of the radiator front, sitting right on top of the tube? I was showing my new (to me) car to a friend and when I was looking in the direction of the front bumber vents, I noticed something blue. Upon further inspection, i saw that there was a small, blue marble ball there and now it's sitting on my desk. No noises were coming from that area though.