530i Strange Noise at 1500 rpm under load
This one is driving me crazy. I have this strange noise, kind of sounds metallic vibration, that starts at 1500 rpm (exactly) and then goes away at about 1800 to 2000 rpm. This only happens under load and if I open my passenger front window it sounds like it is coming from that side of the car. If I open the driver's side window I hear it too but not as load.
This only happens at load. If I'm parked or in netural and rev up my car to 1500 rmp there is no sound. If I press the accelerator harder through this point the sound only happens for a split second. If I hold it steady at 1500 rpm you can definitely still hear the noise.
I have taken it to my trusty independent mechanic and he can hear it too but does not know what it is. I have gotten under the car and grabbed the exhaust, including the cat heat shields, and nothing moves. The rear rubber mount for the exhaust support is in place and provides the proper clearance.
I think the sound is louder in warmer temperatures then cooler ones. I don't think I'm doing any damage to my car but the sound is really annoying. And since it only happens in a small rpm band (1500-2000 rpm) it only lasts a second or two. I really want this fixed as I love my car.