530i Strange Noise at 1500 rpm under load - BMW Forum

espejo · 12-15-2009, 08:36 AM

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.

735540 · 12-15-2009, 09:17 AM

possibly cat internals?/loose clamps??I had a similar issue i had convinced myself was bad cats turned out to be a belt squeaking on the ps pully!

espejo · 12-15-2009, 12:55 PM

I will check that out this weekend. But why does it only make the noise exactly when I hit 1500 rpm and only when the car is moving? If it was a pulley wouldn't it make the noise before 1500 rpm and/or while the car is in park or neutral and I apply the accelerator to get to 1500?

roma · 12-15-2009, 08:22 PM

ok with my experience you might have to check VANOS valve and oil seperator, those are really common on that engine

espejo · 12-16-2009, 07:20 AM

I replaced the Vanos o rings per Besians procedure and the oil separator a couple of monts ago. I do not hear the noise when I first start the car or going below 1500 rpm. However, once I hit 1500 rpm I hear the metallic noise until about 2000 rpm and then it disappears again with no noise.

If I'm driving through my neighborhood and keep it below 1500 rpm I hear absolutely nothing. It is always 1500 rpm so something is coming on at that particular rpm and I don't know what it is.

witeshark · 12-16-2009, 10:17 AM

Could there be an issue with the timing chain tensioner?

espejo · 12-16-2009, 10:24 AM

I replaced the lower tensioner spring a couple of months ago. The spring was slightly compressed but it did not fix the noise.

espejo · 12-19-2009, 10:08 AM

I think I found the problem. I checked the exhaust again from front to back and found that the connection plate was broken. It was literally cracked at the point it goes around the exhaust pipes. It was difficult to see at first and I thought the nut holding it was just loose but when I went to tighten it way too much movement. That is when I saw the crack. Hope this fixes it.

witeshark · 12-19-2009, 10:25 AM

That should be promising. Good luck!

espejo · 12-19-2009, 11:06 AM

Here is a picture of the broken bracket. I swong it down for easy viewing. I ordered the part and will replace upon arrival. Just went for a test drive and it is silent!!!!!!!!!!!!

witeshark · 12-19-2009, 11:46 AM

I think you may have it then!

roma · 12-20-2009, 07:31 AM

good job ,and good luck!