When I first heard about the TD5 I thought it would be a delicate, temperamental thing. Five cylinders? A centrifugal oil filter, for goodness sake? Not like the trusty, pre-rusted iron ingot in the series 2. Having got to know my own and other people's TD5 engines over the last few years I am more and more impressed with them. They chug along for hundreds of thousands of miles and are mouth wateringly tuneable. The key vulnerabilities have been mentioned above - oil pump sprocket falling off and head gasket/head porosity problems. The things that have stopped me have included oil in the injector loom and miscellaneous electronic faults including the ECU, which isn't really the fault of the TD5 engine itself. First car I've ever had for 40,000 miles without having the engine out, or at least the head off.