M47TUD20
The all wheel drive BMW X3 and rear wheel drive BMW 320d models, built approximately between September 2001 and December 2004, were fitted with the M47TU ("M47 Technical Update"). The exact production week is not known, and was probably later than Production Week 33 in 2001 (e.g. one cannot rely on a UK 51 plate registered BMW 320d to have the M47TU).
The engine capacity was expanded to 1995 cc, and it retained the common-rail injector system that had proven popular in the smaller M47R and larger M57 engines. These changes empowered BMW to increase torque and improve fuel consumption, especially at lower revs. However, these modifications added 50 kg to overall weight and emissions raised accordingly. In the 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 also fitted with twin balancer shafts to counteract the secondary balances inherent in a diesel four-cylinder engine. The M47TU was regarded as so good that BMW made it available in the 320Cd Coupé.
Although an extremely well accomplished piece of engineering, the M47TUD20 introduced new common failure points. Chief among these was a new 'swirl flap' mechanism embedded in the inlet manifold. These consist 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 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. Subsequent revisions of this engine involved the replacement of the mechanical method of securing these flaps by a one-piece moulded plastic flap that so far appears to have eliminated the problem.
Applications:
- 85 kW (114 hp) and 280 N·m (207 lb·ft)
- 2003-2005 E46 318d
- 110 kW (148 hp) and 330 N·m (243 lb·ft)
- 2001-2005 E46 320d
- E83 X3 2.0d (up to end of 2006)
Read more about this topic: BMW M47