Metallic rattle sound from passenger side over deep bumps

[SuperPoly]

I’m hearing a metallic sound that almost sounds like two coins touching when going over deep bumps. It’s from the left side, possibly the seat or dash. I have removed everything from the car and searched for loose objects, but no luck.

Has anyone heard this before? Thoughts on diagnosing it?

 

[Arm]

I put some felt/rubber material right along the gap between the dash and A-pillar. Had a lot of rattling coming from there. Silenced it up right away. If you tap the A-pillar area all the way from the windshield and go up towards the door, you'll identify any rattles or lose areas that may be inside or in between the A-pillar and dash it self.

I also have identified rattles coming from the plastic defogger vents at the base of the windshield spanning the dash. You can pop those out and put felt under them too. Makes a big difference.

 

[SuperPoly]

Thanks for your input. I have been knocking and tapping on every surface in the car, but no luck so far. It really sounds like it's in the cabin, but it takes a sizable bump to activate it.

 

[spartacus68]

Sure it's not suspension related?

So there's a couple of bits on the car if you're mechanically minded. One is the ARB link (anti-roll-bar). The bushes wear and you'll get a definite clunk as it's meant to keep the ARB under tension. The other is the coil spring itself. Not unusual for the springs to break or shear, although you'd likely hear a twang on hard-lock to hard lock, also you can measure the distance from the top of the wheel to the wheel arch if you think one might be broken. Park on the flat to measure. With the wheel off is ultimately easier for a proper inspection.

The final one is the top mount and it's quite difficult to detect unless you raise the front of the car on both sides and turn hard lock to hard lock. The bearing carrier is subject to water, road salt and general debris thrown up by the wheel. The aluminium alloy of the mount can suffer from oxide corrosion and it's this that basically sheers the bearing and you end up with a rough metallic sound.

While you're there - check the shock absorber doesn't have a leak or is weeping which might let the car bottom out over a bump.

https://www.mybmwi3.com/forum/viewtopic.php?t=17069

 

[Arm]

I wonder how much it would be do to an all-around suspension maintenance on this car...i.e. say it's about 5 years old and change the struts, shocks, top mounts, etc.

 

[SuperPoly]

Thanks for your thoughts. I was thinking suspension, but it's not any louder when the windows are down. The sound is definitely eminating from the interior.

I took a look at the motor/engine cover and three of the neoprene nuts were destroyed (part #16: https://parts.bmwnorthwest.com/images/parts/BMW/fullsize/349597.jpg)

The bolt and metal washer make the exact metallic sound. I covered all of the washers with anti-rattle tape so that there is no metal-on-metal contact. It seems to have quieted it down, but there is still something making that metallic sound. Are there other commonly broken fasteners in the cargo area?

 

[Arm]

Thanks for your thoughts. I was thinking suspension, but it's not any louder when the windows are down. The sound is definitely eminating from the interior.

I took a look at the motor/engine cover and three of the neoprene nuts were destroyed (part #16: https://parts.bmwnorthwest.com/images/parts/BMW/fullsize/349597.jpg)

The bolt and metal washer make the exact metallic sound. I covered all of the washers with anti-rattle tape so that there is no metal-on-metal contact. It seems to have quieted it down, but there is still something making that metallic sound. Are there other commonly broken fasteners in the cargo area?

Can you record it?

 

[SuperPoly]

Sure, here's the file: http://sndup.net/cgfm

It can be heard twice. Something must be loose, but I'm not sure where to go hunting. It sounds like it's mostly from the rear, but sometimes it sounds closer to the front.

 

[Arm]

Sure, here's the file: http://sndup.net/cgfm

It can be heard twice. Something must be loose, but I'm not sure where to go hunting. It sounds like it's mostly from the rear, but sometimes it sounds closer to the front.

I hear that sound as well in my car. I chalk it up to internal wiring within the panels themselves. Also check the parcel shelf...it sometimes jumps up and down and causes that type of sound. So I put sticky foam tabs under the tabs of the parcel shelf itself.

 

[Arm]

Any luck solving your rattling issue?

 

[SuperPoly]

Nope. Took it to BMW, and an independent mechanic too. It must be something in the door or deeper inside of the car. No longer have the i3.