We are seeing more and more Mini Cooper S vehicles fitted with the N14 come through our doors with the complaint of rattling on start up. The noise you will hear is a very loud rattling noise for just several seconds on cold start up only. The reason for this is that the timing chain has stretched and failed. If your vehicle is under warranty, you want to take it to the dealer as soon as possible and insist that the timing chain, tensioner and all guides be replaced. Do not let them do the tensioner only, as it is not a fix to this problem. This is a major problem that can lead to engine damage. We have seen cars come in with broken chains as well as broken and cracked timing chain guides.
Special equipment is required to do this repair, and can be performed by trained technicians. Do not risk your vehicle with an untrained technician, as this is a major job. We have been servicing and repairing Mini Coopers here in San Luis Obispo for many years, and we understand these cars inside and out. Please feel free to call or comment with any questions you have.