Sorry. I searched and did not find anything, but when I shift in low RPM's I get a significant crack crack crack from underneath. I am new and this just does not sound like a back pressure issue. It sounds more mechanical (donut gasket?). Has anyone had this? When really hittin it, it does not happen.

T.I.A.

 

You're totally sure it's not the exhaust popping? Cooper S? It can be quite loud and mostly noticeable at lower speeds.

 

i does not exit out the back... sounds like it is right underneath me! You think it is normal for an s?

 

I started to look into this and while I expected the natural pop from the back pressure there are quite a few people that are hearing the same that I am. It is a metallic kind of crack sound that is under me, not in the rear where I would expect. Could it be a exhaust leak? Maybe heat shield that is loose?

 

In my car with the windows up the popping sounds like it's coming from the back, but with the windows down, it really sounds like it's underneath me. It used to raise my eyebrows a little when I first got the car and I would shift gears, and the exhaust would randomly pop right when I got the stick into the next gear. I would be like, "holy sh*t" was that my tranny? CRACK!

Of course I'm not trying to convince you that is what is going on with your car, but I felt the need to mention that I at one time thought I had a issue until I realized it was simply the exhaust popping. Hope you get it figured out.

 

Any way you can take a recording of what the sound looks like? The Cooper S is know for its exhaust burble which is essentially sounds like a backfire. Usually when downshifting or coming off heavy throttle it's particularly pronounced. This is more of a muffled popping sound kinda like a firecracker going off inside a sealed container. If you're hearing something more mechanical, it could be two metal objects banging against each other. Almost like the shift linkage is running up against something, but you would have to get under the car and have someone move the shifter around to check.

 

What year is your car? If it is something like an 02, 03 and maybe and 04 you could worry. If it is an 05 or 06 it is probably the exhaust, with the windows down it does sound like it is coming from underneath you.

Here is a test. Try sitting still with the car in neutral and play around with the throttle a little, may rev it, hold at 3k for a little and letting off, etc, and see if the noise happens. If it does it is the exhaust.

 

Thanks everyone for the replies. This forum rocks! It is indeed an 05. It is new to me, and any sound that I am not used to makes me nervous. The sound seems to go away once the car is warm. I am going to try the 3k let off today and post back if it happens still.

I would expect a pop pop pop, but this just sounds more metallic and from under the car. Hopefully I am stressing out about nothing

Thanks again to everyone that replied!

 

Shouldn't be anything serious. Might even be something as silly as some road debris crammed into a heat shield under the car. Keep us posted as to what you find!

 

I have the same thing on an '06. There's actually 2 different sounds. One is the deeper exhaust burble and the other is a more metallic sounding rattle which I imagine is what you're hearing. Both occur after letting off the gas around 3k RPMs. I would say it's normal.

 

When the car is cold it does tend to sound a bit metallic, and the 05's do have the exhaust noises added to them (the earlier ones dont), so I bet your stressing over nothing. Dont worry, I did a bunch of that when I first got the car.

 

I'm sorta getting the same sound from my '03 MC, but usually it does it when I put it in first or second, and accelerate normally. it doesn't do it when i'm mashing on it though. "vvvrrrooo crack oooommm - shift - vrrooomm"

I recently put in a Getrag 6 speed from a 2005 MCS and have the MCS' stock flywheel, which I've heard is a little to heavy for the naturally aspirated MC engine to turn. The sound never happened before the swap, maybe the heavy flywheel is to blame?
I should also note, in 1st and 2nd, up til about 3k rpm, it feels almost like the engine is about to die due to a lack of gas. like it's gonna stall out, but never does.

 

Is it more of a "chewbacca" sound? If it is, it could be the dual mass flywheel getting stuck/unsuck internaly...a known problem with the S flywheel...but not really an issue that affects relialibiliy/driveability. The weight of the flywheel might be what is preventing the car from stalling since you have less hp...the inerta of the heavy flywheel should make driving a car lacking a few horses easier...during times like starts on a hill, etc.
As for the feeling like it is going to die....must because the gearing is wrong for the motors output....if you bought slightly smaller diameter tires, that would be the simplest way to reduce that!

 

I had an exhaust leak in my '05 MCSC that disappeared once warmed up and took forever to find. Finally noticed condensation dripping near the rear flange of the cat after a cold start. Turned out there was a hair line crack on a weld about 2 inches down the the rear pipe from the flange. If I pulled down on the exhaust (when cold) the crack widened and you could see it better. A buddy with a welder fixed and it's been fine ever since.

 

Resurrecting thread since it is "hitting" on the issue that I am observing with my 06-MCSC-M6. This is not the burble or popping sound, which I understand what it is. This sound is metallic as the OP mentioned. Did everyone just assume it is part of the burble/pop and left it be? It sounds really bad since it sounds like metal contact. Only occurs when the car is NOT warmed up, and happens between shifts or decelerating in gear.

Good discussions on problem, but I do not see any solution or root-cause. I will probably dig underneath soon to see if it is anything obvious (ie heat-shield, clamps, cat, etc)

Thanks!!

 

Bump.