Peugeot DV4

The 1.4 HDi — an aluminium-block four of 1,399 cc at 54 to 68 hp, in the C2, C3, DS 3, 207, 307, 208 and the Suzuki Liana, and sold by Ford as the DLD-414. The DV4TD of 2001 to 2009 is the variant most sources describe, and the family outlived it — the 208 carried a 1.4 HDi well into the 2010s.

It is a belt-driven interference engine: if the belt breaks the valves bend. That is the whole of the case for treating its service interval as a date rather than a suggestion, and it is the first thing to establish about a cheap example with no history.

Which injection system it has decides most of the rest. The Siemens cars fail at the high-pressure pump's PCV and VCV control valves; the Bosch equipment is the more reliable of the two and fails instead at the dosing unit. A fuel-system diagnosis on this engine starts by identifying the supplier, because the two do not fail in the same place.

The turbocharger has a modest life, and the crankcase ventilation membrane and the crankshaft damper pulley are both known weak points.