Hey yall, my brother just picked up a 2012 Mini Cooper S with 148k miles. He got it under the presumption that it needed a new timing chain. We took it to a local mini specialist, and they pretty much refused to do a timing job, they inspected the timing chain, tensioners, and guides and nothing was broken, stretched, or off, and they said everything looked basically brand new. They recommended doing a water pump & friction wheel, which he let them do since it was leaking, and the tech said the noise changed when he messed with the friction wheel. After that we went and took it home, and the noise was gone, the only thing left was an unrelated rattle likely from the aftermarket exhaust. I did notice when I was driving it back that it felt like it was soft limiting at about 4800 rpm. Once I got on a road next to my house I did what any reasonable person would do and tried to push it past that and cylinder 1 misfired, I limped it home, we changed the spark plugs, since we just got a new valve cover on it and hadn’t done that yet, it stopped misfiring and soft limiting. For the first half of the drive after getting the new spark plugs the noise seemed to go away but it eventually started again. It sounded an awful lot like something rattling around in the intake manifold, so we took it off and inspected it but didn’t see anything out of the ordinary. We’re kind of stumped at this point, the car runs great, no cel, no codes, literally nothing other than this horrendous noise. The noise is only present around 1800-2500 rpm, and it is quite loud, below are links to a couple videos of it.

https://youtube.com/shorts/jSXyFsH2VrY?si=TVe2goSsWfi2YT71

https://youtube.com/shorts/fFKHOArt1GI?si=Bea-jDWLBFiz6lvn

 

Did they replace the drive belt tensioner? 11287598833 is the part number. I was hearing something similar in my 2011 MCS over the summer and replacing the drive belt tensioner fixed the problem.