NHTSA Complaint #11656692 — 2013 BMW 528XI

The timing chain became stretched so that the valve timing with the pistons had been altered so that a valve face almost hit the top of a piston(one more tooth on the intake camshaft gear would have caused an impact between the piston top and a valve face causing the motor to stall and cease operation thereby causing the vehicle to lose power and possibly control). A timing chain should not stretch so as to cause a strike between a valve face and the top of a piston. Either the timing chain was of inferior quality or the automatic tensioner was inadequate to take up the slack as the chain wore.