Two problems related to diesel engine have been reported for the 2008 Mini Cooper S. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Mini Cooper S based on all problems reported for the 2008 Cooper S.
I have owned the Mini since new. Always regularly serviced at the Mini dealer. Recently I started the engine and it sounded more like a diesel engine, very noisy and unusual. Took it to the Mini dealer and as I explained what the symptoms were, the front desk person that took my details diagnosed the problem. The preliminary diagnosis was confirmed later through an inspection by a trained technician. Like many, many Mini owners I have had a timing chain problem. That the front desk staff can diagnose a problem like this made me curious, it must be such a common problem that the dealer sees it regularly. Some research confirmed this was a widespread problem with Minis. Owners have had terminal engine damage with engines that are low mileage and simply should not have any problems. This issue with the engine is serious and can lead to a major accident because of a catastrophic engine failure while driving at highways speeds. Although I was lucky, and do not have a huge out of pocket expense as I have extended warranty coverage, I still believe this is an important safety matter that BMW/Mini appear to be ignoring. It should be the subject of a vehicle safety recall. It is poor engineering and design on their part, that should be rectified.
Loud engine noise coming from chain tensioner at startup. Sounds like diesel engine. Also happens during cold engine start.