The X150 XK started life with an all-aluminium 4,196cc AJ-V8 in naturally aspirated form for the Coupe and Convertible. It is mated to a six-speed ZF 6HP26 automatic gearbox that was used throughout the XK's lifetime. In mid-2006, the XKR arrived with an Eaton MP112 Roots-type supercharger.
Er, yes, don't forget about service intervals
Both of these variations on the Jaguar V8 engine addressed the weaknesses experienced in the previous XK generation of weak timing chain tensioners and water pumps. This engine uses chains to drive four camshafts and should be trouble-free if the 10,000-mile service intervals have been observed. Oil changes must use the correct 5W 30 semi or fully synthetic oil for the 4.2 units and 5W 20 oil for the 5.0-litre motors. Specialists say the supercharged V8 can begin to rattle at 50,000 miles if its oil services have been neglected or the wrong oil used. Regular servicing should be around £200 for a minor service and £500 for a major service from an independent specialist.
For 2009, Jaguar introduced the 5,000cc V8 in standard and supercharged variants with 385 and 510hp respectively. As with the 4.2 V8, the thermostat can fail and lead to overheating. Another cause of overheating is the radiator becoming clogged with leaves, which can also cause corrosion of the pipework.
Listen out for the cooling fan kicking in when it should. Electric problems mean some cars run with the cooling fan on permanently. This can lead to the dash warning light coming on, which is an MoT failure point.
Another noise to keep an ear out for is a rattle from the XKR's variable valve timing. This is usually due to the hydraulics and requires a new unit.
Jaguar said the automatic gearbox was maintenance-free, but specialists recommend changing the oil at 60,000 miles. The filter in the gearbox sump should also be replaced. If the 'box has a leak, it's most likely the connector sleeve.
A new battery every four years is a wise precaution as many niggling faults with the XK arise from the battery draining rather than any mechanical fault. If the car is left for prolonged periods, a trickle charger is a sensible choice to prevent the battery draining. 2010-on XKs need a specific power management module for trickle charging.
Perhaps the only common complaint from XK owners about the engine is it can be too muted with the standard exhaust. There are several aftermarket options from companies such as Milltek, Quicksilver and Proflow for around £1,500 for a cat back system or £2,500 for a complete exhaust including manifolds.
PHers view:
"I drove 4.2 Litre XK and XKR variants but the moment I sat behind the 5.0 litre V8 in the 2009-onwards car I knew it was the engine to have. The 510hp in the supercharged V8 of the facelifted XKR can almost be a too much in road use."
Andy Burrows