I am distressed to find myself in the process of having to spend a considerable sum of money to rectify an apparently known and acknowledged design fault/weakness in elements of the intake manifold, as well as the repair and replacement of collaterally damaged parts of the "top end" of the engine in my 2003 BMW 330d.
After just 100k miles of regularly serviced and carefully driven miles (rarely exceeding 3,000 rpm) a sudden loss of power and rear end smoke clouds was experienced, immediately found to be the fault of breaking up swirl flaps in the intake manifold. The detritus of broken spindles, rivets and parts of the flaps themselves having nowhere else to but go but into the combustion chambers have caused inevitable damage to piston crowns, valves and valve seats. All this is very expensive both in labour and genuine replacement parts to repair, over and above the cost of a replacement of the primary problem source - the manifold itself. I am advised that this "fault" has been known apparently to BMW for some time, which has, as a result modified the manifold design for production from 2004 to avoid the continuing failure of the component.