UK, the new characteristics of the M47TU were sufficient to lift the BMW 320d into the next highest insurance bracket, and the next highest band for Vehicle Excise Duty (Road Tax). The M47TU was regarded as so good that BMW made it available in the 320Cd Coupé. The M47TUD20 introduced new common failure points. Chief among these was a new 'swirl flap' mechanism embedded in the inlet manifold. This consisted of a number of butterfly valves within each individual inlet tract, which are secured to an actuating rod via two small screws. It has become clear that over time these screws can come loose via vibration etc. When this happens they can end up being drawn into the respective cylinder, causing significant damage to the piston, cylinder head, and valves. If unlucky further damage can be caused to the turbo if the screw then makes its way through the exhaust valve into the manifold and subsequently into the turbo. These failures have occurred in such quantity that a number of specialist BMW magazines have featured articles on the problem including information on how to remove the swirl flaps. For those who wish to perform some preventive maintenance on the M47TUD20 engine, there are companies who supply and/or fit blanking plugs to allow the removal of these swirl flaps altogether. BMW addressed the problem by introducing stronger swirl flaps and larger diameter spindles – made from plastic – in 2006. Applications: and 2003–2005 E46 318d and 2001–2005 E46 320d E83 X3 2.0d (up to end of 2006) M47TU2D20 The engine was updated again in 2004 as the M47TU2D20. Still at , it produced more power across the range. Applications: and E87 118d E90/E91 318d and E60/E61 520d E87 120d E90/E91 320d E83 X3 2.0d (end of 2006 onwards) See also List of BMW engines References External links The UnixNerd's BMW M47 engine page with photos, history and common problems. M47 Diesel engines by model Straight-four engines