Sorry if this the wrong place for this.

I have an 05 R53 with 72k miles. When I start the car there's a strange rattle. It also does it when I shift a little early. It sounds to me like something rattling down the exhaust somewhere but when I had it inspected the guy said it was the belt tensioner but I've heard the videos of bad belt tensioners and its not it. Then when I was having the brakes flushed the mini dealer said they couldn't hear anything. I thought maybe it was the chewbacca glazed flywheel but after listening to videos of that I don't think that's it either. I've been trying to get a video of it but it mostly happens when driving so its hard to capture.

TL;DR:

1. Rattle when first started
2. Rattles a little when revved a tiny bit in neutral
3. Seems to go away once the car is warm
4. Reproducible if I shift a little too early and the engine bogs a little.
5. From the drivers seat it sounds like its coming from the middle underside of the car. Maybe slightly towards the passenger side.

Any ideas? I know these are hard to troubleshoot without video. I'm still working on that. If I had to describe it in one sentence it would be: a gurgling metallic rattle.

Here's the audio clip:

https://dl.dropbox.com/u/173180/MiniRattle.mp3

 

I have a similar issue, I'd describe it the same way you are and under the same circumstances.

I always thought it was the head shield vibrating/rattling due to low note sound from the exhaust.

I have a '05 Cooper with a magna flow cat back exhaust.

 

As far as I know my exhaust is all stock. I'm not 100% sure though. I've only had the car about 2 months.

 

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Added link to audio clip in original post

 

Bump for added audio clip. Any ideas?

 

So at lunch I started the car went around the exhaust and gave it a little tap with my foot and it made the noise. I drove straight to the muffler shop near my work and when the mechanic came out to listen it of course didn't make the sound.

What would make that noise but stop doing it after driving less than a mile?

 

As the heat shield expands from heat it is now a more solid connection. Check the bolts onto all heat sheilds for exhaust system.

 

Thanks. I'll check that. Are those bolts something I can access with the car on the ground?

 

I'm not 100% positive. But they're on the back of the motor under the coolant reservoir. Idk if there are any underneath as I've never checked that far..

 

Yes check the heatshield it sounds to me that its loose and rattling.

 

I'm slightly confused. The rattle sounds likes at the rear of the car but you guys make it seem like the heat shield is in the engine bay? Is that the case or are there multiple shields? Thanks for the input so far.

 

There's a heatshield that is bolted to the exhaust side of the head which covers the primary runners for the exhaust manifold/header. I don't see how that would back out, though.

 

The hangers could be too long and the exhaust too loose, so the exhaust hangers rub and vibrate/rattle.
If you get the car on a hoist you'll see a polished and/or dented spot. That's the part that's hitting. Either saw off the excess hanger (what I had done), or bend it and tighten the exhaust so it can't move.
If you can't find the spot. Just go over the whole lenght of heat shield and push it up and against the cavity under the car, sot that it can't vibrate as much.

 

I dropped the car off at the muffler shop near my work and they tracked the noise down. A factory weld on a flange on the exhaust was loose. They welded it up and so far so good. I'll have to double check first thing in the morning but I think they go it.