This is a really difficult call. If it was me I would probably avoid the N47 engine and go for something else. However there are cars with this engine out there with 170k miles on the clock and I am sure they haven't paid the £1,600 to get the chain changed. Some have been fleet cars. Auto's appear to have been less of a problem due to the smoother gear changes not putting as much stress on the timing chain. I would like to know what the ratio of failures is to N47 cars on the road. I would have thought the failures probably only relate to a fraction of 1%. If you really like the car but find any indication of rattling around the engine, walk away. There are a lot of 320d's on the road and the majority of which I am sure will be fine.