Something For The Weekend – Jaguar XJ40

| 28 Jun 2013

The XJ40’s squared-off nose may divide opinion – if the reaction in our office is anything to go by – but no one can argue that the big Jaguar represents cracking value at the moment.

Launched in 1986, it was something of a trailblazer for the British firm. This was a car that moved the game on from the old XJ6 Series 3, with all-new suspension, a different braking system, lighter body and a precise, electronically managed engine.

The Jaguar initially came with two all-alloy powerplant options, 2.9- and a 3.6-litre versions of the AJ6 straight-six. Both were derived from the V12, but offered quite different driving characteristics.

The former’s single camshaft and over-square dimensions meant that it produced most of its power high up in the rev range.

The larger engine, meanwhile, featured dual-overhead cams and four valves per cylinder, giving it a linear delivery that suited the car. This would further improve when its capacity grew to 4 litres, giving the Jag a 0-60mph time of 7.1 secs and a top speed of 140mph.

The obvious problem with such complex cars is that things do go wrong and they are often expensive to put right.

The XJ40’s electrical system – with its seven microprocessors and 90 relays – is worthy of a special mention and is often the cause of dodgy gauge readings, incorrect warning messages and unpredictable component failure.

For this reason Sovereigns, with their one-piece rectangular headlights, are less sought-after because their high levels of equipment means that more can go wrong.

Rust protection was another flaw of the XJ40 and rot can affect the bonnet, wings, door bottoms, inner and outer sills, the boot floor, bootlid, rear window pillars and inside the filler cap.

The engine is durable if regularly serviced, but not immune to head-gasket failure, so check for emulsified oil inside the filler cap and any signs of overheating. An oil leak at the right-front corner of the head, adjacent to the distributor, can also signal trouble.

The gearbox should also be reliable, but ensure that it operates smoothly in all positions, plus that the fluid is topped up and the correct colour.

As a relatively heavy car, dampers and bushes often need to be refreshed at 50,000 miles – it may clunk and wallow if they havn't been replaced – and check the subframe for rust because it is foam-filled and can’t be welded.

Inside, leather looks better and is harder wearing than cloth. It’s also worth checking that all the woodwork matches.

Finally, ensure that all of the electrical items work because it can be pricey to fix them.

Having said all this, the XJ40 remains a deeply impressive starter classic and one that is only going to get rarer.

Plus, if you speak to clubs such as,, and they may be able to point you in the direction of an XJ that has had its problems ironed out.

The cheapest car on Pistonheads’ classifieds looks to be something of a bargain. It’s a 4 litre, with leather trim and just 50,000 miles showing, although we would advise checking that the history confirms the mileage.

If nothing but the top spec will do, a Sovereign can be had for not much more, this car’s vendor is asking £1995. It comes with 94,000 miles on the clock, having been with its previous owner for 16 years.

The last car on our list is described as a ‘timewarp’ example, having covered just 8600 miles. The prize-winning show car has never been used in the rain and is priced accordingly at £6995.

For many, the XJ40 will be remembered as a chariot of the political classes, just as home outside Number 10 as it was travelling in a police convoy. But that would be to do it a disservice because it’s also an excellent saloon that marks an important time in Jaguar’s history.