I bought a new Transit tdci and had endless issues with the engine, surging, lurching, self revving, poor economy, variable performance, hunting on light throttle...
Although it never actually broke down. You'd put your foot down and nothing would happen for two seconds, then it would take off like a rocket.
When l sold it at 80,000 miles it had early signs of injector problems.
Having said all that the Defender tdci drives well, if you get a good one.
I've driven three. A 90 HT (OK) 110 XS (very nice) and 110 Utility (awful)
TD5 Defenders are all getting on a bit now. There are good ones to be had but there's loads of mint tdci's just out of 2/3 year lease.