Annoying rattling coming from somewhere up front
 

I've searched far and wide to try to find an answer to what is causing this annoying rattling sound I can hear inside the car.

There is a rattling noise coming from either behind the iDrive screen, the steering wheel, or in between the both of them under the dash. It sounds like something is loose and rattling around. I can't tell if it's metal on metal, or a plastic piece rattling against maybe the firewall or some other part.

This is what I've done so far based on possible solutions I've found online:

• It's not the strut support bar in the engine bay. I've confirmed the bolts are tight and even replaced them with new ones.
• I've replaced my tie rods (the whole assembly) as that was also suggested as a cause (plus they needed to be replaced anyway)
• It's not the buttons on the turn signal stalk. I didn't think that would cause a rattle that loud.

As context, I replaced the valve cover gasket, oil filter housing gasket, and oil level sensor within 3 weeks or so prior to when the rattling started. This is all on a '05 525i with under 180k miles.

No rattle when I hit the gas from a standing stop, but when I reach 30 MPH, the rattle starts. Softly at first and as I go faster it gets louder, to a point where it sounds like whatever it is is about to pop out and fall off wherever it is. Then, as I slow down it gets softer and eventually stops when I go below 30 MPH. I'm nervous that if I continue to drive it at high speeds for a long period of time, whatever it is could eventually fall off and fall onto or into the engine damaging it.

I got my car aligned after replacing my tie rods, and Firestone suggested it's the engine cover underneath, I'm missing about 3 screws right now, but I don't think that would cause such a loud rattle, unless its the transmission skid plate, which I doubt?

All that being said, I cannot figure out what is causing this annoying rattle. Any suggestions out there? I really don't want to pull my dashboard apart.

Please help my sanity while I drive my car!

I will probably be better if you post a video of the noise

Whatever that object is, it vibrates only when you reach its resonance frequency. Those are the toughest, BMW couldn't even find mine. Where you think you hear the sound, isn't always where the object is located. I ended up finding mine myself. It'd probably be a good idea to invest in a mechanics stethoscope.

Did you ever figure out what was causing yours?

I had an idea about the metal transmission plate, could one of those screws be loose causing this as well? I remember I had to remove that when I changed my oil level sensor....

A video would be helpful, here's a clip from my dashcam. It has a mic for recording audio inside the cabin and you can very clearly hear the rattling noise. My speed is at the bottom, it picks up more as I speed up. Sometimes when I hit a bump it stops for a quick second before picking back up again.

Mine was a weak rubber seal, causing the window to rattle. Wow, yours sounds very annoying. You'd probably need to get that stethoscope and have a friend do the driving. I didn't have a driver, and so it took me much longer. So if you rev the engine standing still, there's no rattling?

Is that a rattle or something slapping the underside. Im thinking something on the driveshaft slapping the underside at speed, or maybe a tire belt or tread slapping. Check underneath and your wheel wells. By the way the video is worth a thousand words. Good luck

You reminded me of when I had a similar rattling noise on my e36, I could tell it was underneath though, it was caused by the Flex Disc.

If it doesn't rattle when revving the engine in park, then yes, it more so sounds like driveshaft or extremely worn tires.

Someone told me it could be the metal plate covering my transmission, a bolt holding that could be loose so the plate vibrates as it drives . Or potentially bad engine mounts. How could I tell if it were the engine mounts? Have not tried revving the engine standing still to see if it produces a rattle, will try that this afternoon. I'll also crawl underneath and give that metal cover a slap.

My tires are brand new, replaced them last Fall and thanks to COVID have not driven the car farther than the grocery store a mile and a half away from my house.

If it was the engine mounts, the whole car would excessively vibrate whenever the engine is running.

It sounds awfully pronounced, like the rattle is in the cabin. If it were related to the recent engine service I'd think the noise would be a bit more muted (ie, socket on the engine somewhere but has to go through the firewall/winshield). Silly, but have you looked under the seats for something that fell underneath? With the sub covers being plastic it could be something like that. Perhaps something in the sunroof?

What if you put the car in neutral coasting from 50 or so mph? Basically take the engine out of the equation so that it's only road vibration as input. Seems likely it's not the engine given the 30 mph noise threshold, and no vibration with revving in park but doing that would confirm.