Last March my '06 S developed the loud "diesel" sound like a stuck valve or something so I replaced the timing chain tensioner and the noise went away. It came back tonight out of the blue. Oil level is good, no codes, good power, etc. No noticeable affect, just the noise. Does anyone else have experience with a tensioner failing so soon? I suppose I don't know for sure that it is the tensioner but that's where I would place my bet.

 

Was it a OEM Mini tensioner? Would be interesting to know if it was or not.