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Ik kwam een meer dan prima Buyer's Guide tegen op Pistonheads over de XJ40. Kopieer 'm hier even, ter lering en vermaeck.


URL: https://www.pistonheads.com/gassing/topic.asp?h=0&f=23&t=2002052


I think it is fair to say that the XJ40 will always be overshadowed by its predecessor. This was probably inevitable given the delays in the car's launch (the styling was pretty much finalised by 1981) - and the particularly high regard held for the Series cars. They're still a beautiful car though and are comfortable, smooth riding and very good to drive. They also have the distinction of being the last car to have design input from Sir William Lyons.

The XJ40 was launched with a great fanfare of publicity - the BBC even made a TV programme about the car - and was greeted with almost universal praise and enthusiasm, with several publications describing it as the best saloon car in the world. 'Car' magazine devoted much of their November 1986 issue to the XJ40 and even after the car's reputation was tarnished amongst other writers, LJK Setright remained impressed by the car's technical accomplishments preferring it to the new Lexus LS400, though he mourned the lack of development in the Jaguar.

Unfortunately production quality and design issues affected the early cars, particularly with the then very modern electrical system. The dash module design included a daughter board which was not well enough supported and led to dry solder joints which caused all sorts of phantom faults to be displayed on the VCM screen (Vehicle condition monitor - a small screen to the right of the right of the rev counter), with would then wrongly display messages such as "Brake failure", "Fuel failure", "Low battery", "Bulb failure" etc. There was generally nothing actually wrong with the car but the VCM certainly gave the impression to the owner that the car was completely banjaxed. Early bulb failure modules were also inclined to fail for the same reason, but replacement with a later version solved this. The rear suspension of the XJ40 is particularly sophisticated, allowing the axle to float slightly to increase compliance. Very early cars were subject to a recall to replace the mounts which could wear prematurely - which was seized on by the car's detractors as yet anther example of them being somehow 'rubbish'.

Later cars with the 3.2 and 4 litre engines had a new electical system and were more reliable than the average car at that time. The final version of the XJ40 from late 1992 though they look almost identical had a redesigned front structure shared with the X300. These had a new electrical system once again and won much praise for their reliability at the time. The late XJ40 was amongst the most reliable of cars sold in 1993 but by then the stereotype was entirely unassailable. The later cars are still reliable today providing they are in decent condition.

I made a reply quite a few years ago about the things to look for on the XJ40 in the 'Smoker barge 1-5K' thread. I paste it here:
They're very good cars - I love mine and have never tired of it despite having owned it for a long time. The mechanicals are pretty robust - especially the engine and transmission, neither of which have any particular weaknesses and weather the lack of servicing most of them have had well.

There were three distinct phases of XJ40 - the 2.9/3.6 litre digital dash cars running from 1986 to 1989. The digital dash is cool - but the cars can be quite needy electrically - these are the cars which earned the XJ40 its reputation for being unreliable.

The early cars have a 2.9 or 3.6 litre engine and are fitted with a digital dashboard. This can suffer dry solder joints which brings myriad electrical problems. The various modules are simple by modern standards and are generally repairable. There are the cars which gained the XJ40 its reputation for unreliability.

In 1990, Jaguar introduced an analogue dash with six dials and a new electrical system. This is MUCH better and more reliable. XJ40s of this era are reliable electrically, unless they have rust problems. 1990 also saw the 4 litre replace the 3.6 in 1990 and 3.2 replace the 2.9 in 1991

And lastly the 1993/1994 battery in boot cars (introduced October 1992) have over 100 metal changes from the earlier XJ40 and under the skin are almost an X300. These drive slightly better and have slightly different seats with 10 way electrical adjustment. These have another entirely new electrical system which is very reliable - again unless they have rust problems. Bad earths and soaked electrics can affect them.

XJ40s can rust - really rust - so check carefully for it. The areas to check are:

On late cars (1993 and 1994 model years - these are the cars with the battery in the boot) - the bulkhead behind the engine can rust badly - indeed terminally. Check it in both corners where it meets the inner wing and down the weld in the middle. Some rust here is inevitable, but if there is serious rust here - walk away unless you like welding!

On all model years with the bonnet open, check the tops of the inner wings. XJ40s can rust round the small white plastic lokut nuts which old on the screws which secure the wheel arch liners below.

Look at the top of the plenum - they can rust badly here, but generally invisibly under the wings. The tell tale sign of this without removing anything is to examine the ends of the front wings where the touch the plenum next to the plenum cover. If they are swelling, then there is rust under there. That said, this isn't especially expensive to fix.

On earlier cars check the front corners of the bonnet - these can rust badly. Fortunately, later cars are unaffected and the bonnets are interchangeable.

Check the A pillar on both sides. These can rust through, generally near the base - and especially on sunroof cars. They're not cheap to fix, thought the parts are available. (This reply was 2014)

Front wings can rust in two places - firstly at the bumper mounts at the front and at the point where they touch the plastic front spoiler.

Front wings also tend to rust at the bottom along the sills where the rain water is channelled behind them. If allowed to develop, they can also show rust blisters about six inches up at the rear of the front wing - following the line of the rain channel welded to the inside face.

While you are looking at the lower wing, check the sill ends on both sides. Sill ends and the rear of the front wings tend to rust together. If both are rusted, there is likely to be more rust lurking behind.

When you are examining the sill ends, check their inner face too - the side which projects into the wheel well. They can rust badly here whilst looking sound on the visible side. A mirror will be useful to see this.

Late XJ40s can rust on the inner wing around a wiring loom grommet, which can allow water into the car soaking the fuse boxes on both sides. Earlier cars don't have the grommet - but strange electrical faults in late cars can often be sourced to leaking inner wings. Dry solder joints in these fuse boxes are also not unknown.

Check the front of the floor under the foot wells on both sides. These tend to rust at the corners behind the wheel where the floor meets the sill end, and at the jacking points.

Check for rust at the sill to floor join all the way down the car on both sides. This is important as rust is common here, but easily spotted. The place to look is along the pinch weld where the sill joins the floor ON THE FLOOR SIDE under the car.

Early cars can rust at the rear of the sills, but this seems much less common on later cars. Rear wheel arch rust is worth checking for, but is much more of a problem on the X300. Generally an XJ40 will be really rotten before its rear arches are frilly.

Front subframes rusted badly on early cars, but later cars are much less affected - check the front subframe carefully if you are looking at a digital dash car.

That's enough scrambling around on the ground! Now check the rear screen surround, paying particular attention to the finisher which covers the weld along the rear pillar - and the deck panel in the corners where it meets the screen and around the fuel filler. The rear pillar finishers swell when they are rusting, pushing them out at a strange angle. Serious rust here can lead to leaks into the cabin and boot.

The deck panel behind the boot lid isn't structural (it is bolted on at the sides) but rust here is unsightly and can lead to leaks into the boot.

Boot lids rust badly on early cars, but later cars don't suffer rusty boot lids that often. The late boot lid is not identical to the early one, but the two are interchangeable.

Famous last words, but boot floors don't generally rust badly, though the boots themselves often leak. A wet boot is likely to be down to a leak from the fuel filler/gaiter, poorly sealed lokut nuts securing the rear chrome trim at the boot opening, a leaking aerial grommet or leaking rear lights - or if you are unlucky, rust at the rear pillar finishers. Leaky boots are common on XJ40s.

To the inside.

I would be suspicious of any XJ40 which is wet inside. Lift both front carpets to see if they or the underlay are damp. If they are, it could mean the car leaks - that means rust is likely on the bulkhead somewhere.

The leather trim lasts well with the exception of the piping down the door side of the driver's seat. This can show some wear even on cars which have only done 70,000 miles! Daimlers suffer less than Jaguars because the seat design is less 'wrap around'. The rest of the seat should be in good condition. The woodwork is proper veneered wood and does tend to fade in the sun. Water damage can show on it too. Double check for rust if they look like they've got wet!!

Check the windows all work and the fans work on lower speed settings. The blower motors are controlled by Darlington resistors. If these are on their way out, the blowers will only work on 'high' settings.

The A/C seems to be rather a temperamental thing on the XJ40. It probably won't work. If it does, this is a good sign in my book.

Strange electrical gremlins can be caused by low battery voltage, and in post October 1992 cars by dry solder joints in the two front footwell fuse boxes or by a problem in one of the relay modules. One of these (DBC10009 - yellow base, module H) is FAR more likely to fail than any of the others (which are notably reliable) and can cause problems with the tail lights, the radio and cigarette lighters. Modules are easy to repair - they're just a box with 4 relays inside - 'Module' makes them seem much more high-tech than they are!) The latter two problems are more likely to be encountered when owning the car rather than when choosing one though.

Later cars have very reliable electric seats indeed. I have seen reports of switch problems on earlier cars, but the switches are widely available second hand and cheap, so they can't be that bad. It is important for the electric seats to work - for the MOT and drivability.

The headliner is very similar to the cloth one used on the Rover SD1 and suffers the same BL droop! They can be re-trimmed easily enough though.

As with any car, check the warning lights . On the post 1990 cars the ABS system has two lights - the yellow light should go off after about 30 seconds. Much more than this means the accumulator sphere could be nearing the end of its life. If it comes back on again when you set off, you probably have a faulty ABS wheel sensor. Corroded ABS wheel sensors (tends to be the rear ones which corrode) can also cause the speedometer not to work. The ABS computer is in the boot. It is reliable unless it has got very wet.

If the transmission selector needs to be wiggled in order for the car to start, the park inhibit sensor needs adjustment or has problems. Not particularly difficult to fix.

The car should start easily and quickly and settle to a steady idle of about 800 rpm when cold fairly quickly (less when warm, particularly the 4 litre). Higher than this means an air leak, an idle valve problem of a throttle position sensor problem. They can be tricky problems to find. Slow starting with long cranking time can be caused by a failing fuel pressure regulator or by a faulty crank position sensor. The CPS normally fails completely however - with no spark or fuel. Older XJ40s with a failed CPS display no revs on the rev counter when cranked to start. On later cars this tell-tale isn't true: the rev counter only springs to life when the engine fires.

The engine should be smooth and quiet - though it is less refined/more raw than a modern BMW, for example. The transmission should select drive and reverse without clonks or histrionics. It should change smoothly through the gears at part throttle but you will feel changes at full throttle in a way you won't on a modern car. A clonk lifting off power can mean drive line problems - a worn cv joint, prop centre bearing (tend to roar too) worn Jurid/ worn diff/output bearings etc. Diffs can get noisy but die very slowly.

Look for smoke. A small puff of smoke at start up is acceptable - most XJ40s do this; it is a product of the valve stem seal design. Smoke when driving along can mean a problem though - check the car doesn't smoke on acceleration or after rapid deceleration.

The oil pressure gauge is notoriously flaky on all AJ6 engined Jaguars. Real oil pressure problems are almost unheard of. Unless there are other signs of low oil pressure in the way the engine sounds and feels, then a low reading is almost certainly a faulty gauge.

The XJ40 is a heavy car so worn bushes is not uncommon. They don't tend to suffer broken springs like German cars. The car should ride well - though firmer than a Citroen CX, for example. The car should drive straight without tramlining and pull up straight under braking. The car should corner and handle well with no sogginess. It should be surprisingly good at challenging roads, particularly with a poor road surface - though the feel of the car encourages wafting. The brakes are good for a car of its age and weight.

Knocking from the front suspension over bumps is probably shock absorber top bushes. These don't last well, but are cheap and easy to replace. The sound of golf balls bouncing round in the boot is probably rear shock absorber top bushes failing - not drastic, but more involved than the front. The sound of a little dwarf tapping the boot floor with a tiny hammer is likely to be rear shock absorber lower bushes.

Look at the front tyres: as the bushes wear, the suspension has a tendency to sag and toe-out. This causes rapid wear to the inner part of the tread. The steering of the XJ40 is very sensitive to suspension geometry. Poor geometry ruins the feel!

Check the power steering does not have heavy 'dead' patches - particularly when it is cold. These seem to affect the early car much more often than later cars however.

Which engine?

The best engine choice in my view is the 4 litre. This is usefully faster and has more torque than the 3.2. It is hardly any thirstier. The 3.2 is also a fine car however and has plenty of performance for most people. the 4 litre also has a more advanced transmission (ZF4HP24), but the ZF4HP22 in the 3.2 is also a good unit.

I would avoid the 2.9 unless it is very cheap. 165 bhp is not enough in this size of car and the single cam 2.9 litre engine has cam chain and breather problems not suffered by the twin cam 3.2/3.6 and 4 litre cars.

The 6 litre V12 is wonderful , but drastically thirsty and significantly more labour intensive to keep running. It is a decently robust engine, but sensitive to maintenance (such as timely coolant changes)in a way the unkillable AJ6 is not. Some parts availability is difficult on the V12. Everything is cheaply available on the six cylinder cars. The V12 is expensive to own - one for the enthusiast, really.

Digital dash cars are cool, but much needier. Analogue dash cars (particularly 1993/94) model years are much easier to own.

Spec level? Daimlers are poshest - with individualised rear seats and picnic tables on the front seat backs. Some Daimlers have soft Autolux leather.
The Sovereign is the model down - but has most of the Daimler's kit, so electric seats, leather, A/C cruise control, etc. both Sovereign and Daimlers came with fishtank headlights originally. The lights are easy to swap for quads - many have been.

The XJ6 the entry level model, but most have leather and alloy wheels. They don't tend to have electric seats, cruise control or A/C. These were fitted with the round 'quad' headlights.

Late XJ6s came in two additional versions - the 3.2S/4.0S and 3.2 XJ6 'Gold'. The 3.2S/4.0S cars have a good spec with particularly attractive interiors using rose stained maple veneers, and often magnolia leather with red carpets. The have a lowered suspension with stiffer springs. Their spec is still lower than that of the Sovereign however. The 'Gold' is mechanically identical to the standard 3.2 litre XJ6, but has leather seats with wider flutes, alloy wheels and metallic paint as standard. Again, these have a lower spec than the Sovereign.

Personally, I would buy on condition rather than colour or specification.

If you are patient, I think it is perfectly possible to find a decent XJ40 for £1,000 (reply is from 2014). They have risen in price, but they remain difficult cars to sell!

Mine averages 22mpg running round. 18mpg in city driving and late 20s on a run.

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