Jaguar AJ-V6 (3.0)

Jaguar's 2.5 and 3.0 litre V6 petrol — the engine of the S-Type, X-Type and early XF, and derived from Ford's Duratec V6 during the period Jaguar was part of the Ford group. That lineage means Ford material on the Duratec 30 is frequently applicable.

It is a belt-driven, port-injected design with variable valve timing on later versions, and it is regarded as durable. The item that decides these engines is the timing belt, on an interference design, with the water pump driven by it — so a weeping pump behind the cover is on a much shorter clock than an external leak and turns a service item into an engine rebuild if ignored.

The other recurring findings are the variable valve timing actuators, which rattle on start-up when oil condition is poor, and the plastic cooling-system components common to the era. On the X-Type in particular, the all-wheel-drive installation makes access noticeably worse than the rear-drive cars.