The Phantom Noise! (with video!) (like gravel in a coffee can, from under the car?)

[Trent54]

https://www.youtube.com/watch?v=vlMIu2tVYLU

I'm not sure when this started. I don't drive it so much, and I can only hear it w/windows down at less than 30mph. It does not seem to be the exhaust that is rattling. I can't move it around really w/my hand, and I can't feel it vibrating when the car is running.

It may have started when the car had a small fall backwards off rear jack stands. It's a long story, but all the wheels were on. I had the front wheels on ramps, but had used a floor jack to raise higher to get better access to the calipers to bleed. Basically I realized I might be in danger of not being able to ease it down, so I put the front wheels back on before trying. When it came down it came down hard (floor jack unloaded all at once) but the tires and suspension absorbed the blow in the front. In the rear, it looked like the jack stands might tip over backwards, so I had stacked the old front discs under the rear pumpkin to prevent the car from impaling itself on the jack stands. I was hoping I could ease it down, but these precautions saved the car, and me, when that didn't work.

I think the fall may have frayed one of the exhaust hangers in the rear a little bit, but I can't move the exhaust around by hand, and the rattle really does not seem to be coming from the exhaust. Otherwise I know I would be able to the feel vibration of the noise when touching the exhaust w/the car running (cold, of course)

The noise is definitely coming from the front under the transmission/engine area (as you can hear), and I'm fairly certain nothing in that area impacted anything.

Thanks to anyone who may have an ear for e34 noises!

[nike32]

Exhaust is double pipe, and it can rattle inside.
I had that on e38, but it sounded only when cold as a bad rattle from under the car, after it warmed up, no noise, only on hard acceleration.

Problem was that manifold is double piped, and original welding failed and pipe started vibrating on the inside.


Lähetetty minun ONEPLUS A5010 laitteesta Tapatalkilla

[ross1]

climb under and bang on those cheap cats. My guess is that the "brick" is loose or broken up and rattling around.

[Trent54]

Double pipe...I never would have guessed. Wish I was kidding!

This explanation totally makes sense because it sounds like an exhaust rattle.

And yes, those cats are cheap! I think when you add up the energy that goes into producing them, and replacing them every two years to pass emissions, they may be an example of 'burn the village in order to save it' :) I did have a noise with the last set (until it burned out, I think), but it was totally different.

I will bang in the morning but I'm feeling better.