2001 Jeep Cherokee 4.0L Petrol · LP51 PKF

Corrosion is the XJ's biggest enemy and the most likely reason these cars disappear from UK roads. Octane reports that door bottoms, sills and wheelarches go frilly and that more serious problems lurk underneath, while Hagerty notes moisture collects behind the rocker panels and rear quarter panels — structural areas on the unibody — and later models are especially prone to rust in the pinch welds at the bottom of the doors. Floor pans can rot out, particularly where a leaky windscreen or heater core has not been addressed. Left untreated, this is structural corrosion and can be uneconomical to repair on a low-value classic.

The XJ's 4.0-litre straight-six is fundamentally strong, but Hagerty reports that every 2000 and 2001 Cherokee with that engine was fitted with a faulty 0331 cylinder head prone to cracking, which mixes oil and coolant and can destroy the engine. Octane adds that the VM Motori turbodiesel is more troublesome if neglected and that the head gasket and cooling system must be in good health. A failed head or gasket causes overheating, loss of power and mayonnaise under the oil filler cap — a major bill on an otherwise simple, rugged engine.

Later XJ Cherokees, particularly 2000-2001 models, suffer cracking in the door-panel wiring harness where the cables flex between the door and the body. The insulation breaks down and strands fracture, leaving power windows, central locking, door mirrors or speakers inoperative - often on just one door. Octane describes the XJ as notorious for tedious electrical gremlins with erroneous dashboard errors, while Hagerty notes the door harness is highly prone to cracking on later cars. Because the faults are intermittent and tied to door movement they can be mistaken for a failed switch or module. The fix is splicing in new copper wiring through a tight space, best left to an auto-electrician, and it is a common source of frustration on an otherwise simple, durable vehicle.