WHAT TO LOOK FOR
Rustproofing of early examples wasn’t great and a bad one isn’t worth saving, so examine the sills, door bottoms, wheelarches and the seams of the front inner wings. Mud trapped beneath the wheelarch liners rots the rear lower section of the front wings. Look around the fuel filler and sunroof opening, and don’t be surprised to find bubbling in the leading edge of the bonnet and edges of the boot lid. The good news is that panels, new and secondhand, aren’t hard to find.
Watch for moisture
Pay attention to the A-pillars and front bulkhead. Sorting the latter might require engine or dash removal, and serious rot in either area could send a car to the breakers. The boot needs particular attention as it could be prone to water leaks, rotting the floor panel; if the boot lock has failed, preventing access, be very wary. And if you’re tempted by the sporting XJR, check the condition of the unique body kit as replacement parts are scarce.
Is it leaking oil?
Specialists consider the engines to be bombproof, and they’ll cover big mileages if maintained properly. The six-cylinder AJ6 units are especially durable, but check for oil leaks and misfires, the rattle of a worn timing chain (which points to infrequent oil changes) or broken tensioner, and signs of a leaking head gasket. The V12, on the other hand, is complex and needs to be treated with caution. Inherently reliable, it’s trickier and more expensive to fix, so a car without detailed service records is a potential money pit.
It shouldn’t sound clunky
Various transmissions were used depending on the engine fitted. Manual cars got a five-speed Getrag ’box, while the four-speed autos were by ZF (six-cylinder) or GM (V12). None are especially troublesome, but regular oil changes – preferably every 30,000 miles – are the key to longevity. Back axles were by Salisbury or Dana, depending on age and model, with the former considered the more robust. Either way, listen for clunks or whines and check for signs of oil leakage.
Jags shouldn’t sag
The weight and performance of an XJ40 puts a strain on the brakes and suspension, so look for evidence of regular work. Front wishbone bushes don’t last long, with pulling to one side a sign of failure, while the A-frame bushes around the differential last around 50,000 miles. The self-levelling rear suspension in early cars can be troublesome and needs checking for leaks and sagging. Many have been converted to the conventional spring/damper set-up fitted