Jaguar AJ-V8 (5.0)

Jaguar Land Rover's 5.0-litre V8, naturally aspirated and — in the form most people encounter — supercharged, powering the XF, XJ, F-Type, F-Pace, Range Rover and Range Rover Sport.

The fault that defines it is specific and expensive: timing chain tensioner wear, most pronounced on the earlier engines, where the plastic tensioners and guides degrade and let the chain slacken. It presents as a rattle at start-up that fades, and progresses to timing-correlation codes and, at worst, a jumped chain. On any early 5.0 the start-up rattle is the diagnosis, and the repair is a large front-of-engine job.

The supercharged versions add their own themes — the supercharger's coupling and the water-cooled intercooler circuit, which has its own pump and can fail without affecting the main cooling system. Direct injection means intake-valve carbon accumulates at mileage in the usual way.