Mahindra MDI / m2DiCR

Mahindra's own 2.5 direct-injection diesel, and the engine under the Bolero's 2.5 common rail and the first-generation Thar's 2.53 DI.

It is one block through four names, and the names mark the fuel system rather than the engine. MDI3200 is the naturally aspirated version on a rotary jerk pump; MDI3200 TC is that engine turbocharged, from 2005; m2DiCR is the 2008 move to electronic common rail; D25 is the BS6 version with a particulate filter and a lean-NOx trap. So the badge tells you what the injection is, and the injection is the whole of the difference in how it is diagnosed.

⚑ Two other Mahindra diesels wear a 2.5 badge and are different engines. The Peugeot XD3P is 2,498 cc and indirect injection; the NEF is 2,498 or 2,609 cc and a different family again. All three were sold in the Bolero and the Scorpio at overlapping dates. Establish the displacement and the injection type before reaching for anything.

Its lineage is agricultural and that is its character — the MDI engines descend from Mahindra's IDI tractor engines, which descend in turn from an International Harvester unit. It is slow-turning, heavily built and undemanding, and most complaints are injection rather than mechanical: injector wear, a tired lift pump, contaminated fuel. A hard start with a knock that clears as it warms is usually injector return volume, measurable in half an hour with a set of bottles and no diagnostic equipment at all.