XK8 / XKR (X100) 1996-2006 Buying Guide

Codenamed the X100, and officially classed as a Grand Tourer, the XK8 was available with a normally aspirated V8 engine in both Coupe and Convertible body style from the onset, with the Supercharged XKR arriving in 1998.

There are two generations of the X100  – the first generation being the 1996-2002 4.0 litre V8 which have a 5-speed ZF gearbox for normally aspirated cars, or a 5-speed Mercedes gearbox in the supercharged models. In 2002 the engine was upgraded to a 4.2 V8, and gearboxes upgraded to a 6-speed ZF  automatic for both normally aspirated and supercharged. Approximate production numbers were around 72,000 of the 4.0 litre cars, and just 18,000 of the 4.2 litre, making the 4.2 a much rarer example.

There is little doubt that if you are looking for an XK8 or XKR you will know something already about the notorious “Nikasil” (short for Nickel Silicon Carbide) engine issues which plagued Jaguar during the first few years of production. The use of Nikasil was a great idea in principle and had been used in all manner of racing car engines for decades, increasing both performance and efficiency. Unfortunately the fuel sold at most petrol stations of the late 1990’s era was a much lower quality than race fuel and contained much higher levels of sulphur, and the manufacturers that were using Nikasil (not only Jaguar but notably BMW and Ducati) began to see some engine failures. The Nikasil issue is no longer a problem as todays fuels do not have such high levels of sulphur. We can state that some of the quickest feeling XK’s we have driven in recent years are Nikasil type, and just one engine of the hundreds that we have opened up in the last ten years showed visible signs of “bore-wash”. The last of the Nikasil engines rolled off the production line on 18^th August 2000, and from then on the engines were steel lined.

Future Value

The great news for a prospective XK owner is that the market looks to have already bottomed out, and it is clear that values are rising. The XJS is a good example of what to expect – average mileage cars that would have once fetched £3-£4k are now being advertised at £10k+.  We would also say that higher mileage cars are not necessarily something to be avoided. The highest mileage XK8 we have driven had a whopping 335,000 miles on the clock and felt better to drive than some 60,000 milers. The vehicle was still on its original (Nikasil) engine and gearbox, and had been serviced every 10,000 miles from new with every service stamp up to the point where there was no room left in the service book, and copies of invoices thereafter. Proof indeed that a well looked after high miler can be a better car than a low miler that may have nothing more than MOT history to verify its history, or long time gaps between services.

It is fair to say that a low mileage car probably represents the best value as a future investment, but if you are looking to get the most enjoyment, hopefully with a steady rise in value, then a higher mileage car is maybe the way to go.

Comparisons With The Aston Martin DB7

There are many words on the internet that compare the XK with the DB7. The truth is that the two have very little in common. Having stripped both of these models down to the smallest parts, we found that the only parts that directly crossed over were the seats (different leather but the same frames,  motors and modules), the battery holding clamp, rear drive shafts, wheel nuts and some relays…

Looking For Signs oOf Accident Damage

The first most obvious sign of previous accident damage will be the wooden Airbag cover in front of the passenger seat. If this doesn’t perfectly match the coloration or pattern of the adjacent center vent piece and the instrument cluster then there is a reasonable chance the car may have been repaired on a budget following an accident that was substantial enough to blow the airbags, and further checks will be needed. Look for obvious signs of damage and be prepared to walk away from anything that may have had a shunt.

Of particular concern would be the front aluminium subframe assembly. Any twisting or distortion of this will be causing excessive tyre wear. Look for signs of worn shoulders on the tyres, and be wary of “brand new” tyres that may have been fitted in order to mask this problem. Look through any history or invoices relating to work carried out or parts fitted. If there is an invoice for front tyres then look at the mileage, or the date of the invoice and cross check against the MOT history to work out the approximate mileage the tyres were fitted. And it doesn’t end there…

The front top wishbone is secured to the front subframe by way of a fulcrum bolt approximately 10 inches in length. Another potential cause of high tyre wear could be movement of the fulcrum bolt within the subframe (approximately one in five cars suffer). The damage is caused by neglecting wear in the wishbone bushes – instead of the bushes “absorbing” the movement of the wishbones, the fulcrum bolt starts to move within its perfectly rounded fitting and causes an “oval” shape in the subframe. This in turn allows the wishbone to move about too much and ruins the front wheel tracking. Good replacement subframes are going to be difficult to find.

Engine

The Drive Belt is easy to check and well worth changing as soon as possible if you can see cracks or splits in the ribs. Look at the drive belt idler pulley where the belt runs “ribbed side up”. The belts do break and can suddenly leave you without the water pump and power steering.  Almost all the cars we have seen this happen have been on the motorway, and the car will very quickly overheat if the belt snaps with nowhere to safely pull over.  It is well worth keeping a drive belt as a spare in the boot (don’t forget you would also need a 15mm spanner or a bar to lever the drive belt tensioner at the roadside).

The same goes for the supercharger belt on the XKR, although if you can see any splits in this then change it with a bit more urgency.

Noises from the engine itself can be critical. When inspecting a car for the first time you will need to be listening very carefully for any knocking noises coming from the bottom end indicating either crankshaft main bearings or big-end (piston connecting rod) bearings. This will be most obvious under acceleration or engine overrun. A quick on-off blip of the throttle while stationary (up to 2000rpm approximately) will usually be enough to detect an issue. The sound will increase or decrease with engine speed, and can best be described as a deep metallic tapping noise which will come from very low down in the engine.

Timing chain noises can almost be expected, and the early plastic design of chain guides and tensioners has now been superceded by metal tensioners and guides (this type have plastic rail with metal body). The car you are viewing may well have had replacements at some stage, but if there is no evidence of a change then you should really consider having this work carried out in the short term. Rattling noises at cold start up are a classic sign of faulty tensioners.

In the unlikely event that the seller of the vehicle will allow you to perform a compression test, expect readings of over 175psi+ across all 8 cylinders.

An engine management warning light on the dashboard will, 99 times out of 100, be caused by more than either a Lambda sensor or Knock sensor fault, so don’t be too afraid of seeing this. It is more important that you can hear the engine is sweet and healthy. Both types are easy to change, except for knock sensors on a Supercharged engine (sadly they are located under the supercharger in the middle of the “V” and may take a couple of hours labour to change).

Gearbox

Believe it or not, on the 1996-2002 4.0 V8 models a “Gearbox Fault” warning on the dashboard can sometimes be fixed by a simple Hard Reset (see our blog post for instructions on how to perform this). This procedure can be known to delete electrical gremlins that expensive diagnostic equipment cannot.

Correct gearbox oil is vital, and this can be visually checked by cracking open the gearbox oil cooler pipe on the coolant radiator and using a white tissue to catch some of the weeping oil (the gearbox oil is cooled within the main engine coolant radiator). All too often we have seen these filled with regular (red colour) ATF Automatic Transmission Fluid and the driveability is simply awful. The car will engage gear from park in a manner that will have you believing somebody has just run into the back of you. The best oil, for the nicest drive and silk-like gear change is the manufacturers specified Esso LT71141. However, this is expensive and an ideal compromise for budget and quality of drive is Dexron 3 grade.

A further minor detail, but common enough to be a concern is “milky” looking oil in the gearbox. This can be caused by a fault within the radiator, allowing engine coolant to mix with the gearbox oil. The leak can be tiny, and the gearbox will probably still function as normal. However, it won’t be doing the gearbox any good and will be costly to repair – requiring both a new radiator and several “flushes” of the gearbox (you will only get 70% – 80% of the gearbox oil out of the system when draining the gearbox sump).

The XK8 4.0 (i.e normally aspirated) does have an achilles heel when it comes to its ZF 5HP24 gearbox. These gearboxes are specified as “sealed for life” but can and certainly should be serviced routinely with fresh oil. It would seem that regular use keeps these gearboxes working. Unfortunately most XK8’s are used as a weekend car or worse still a summer-only car and sit parked for the rest of the year. The aforementioned 335,000 miler is a great case in point.

4.2 Models should be tried in “Sport” mode. If Sport mode (also known as “Performance” mode is not available (i.e the gearbox will not kickdown when throttle is pushed to the floor) the fault can be the Linear switch on the side of the gear lever. The first sign of this will be a flashing red light on whatever the selected gear on the J-Gate. Easy to change with basic tools but a fairly expensive and rare part to obtain.

Bodywork

The X100 does suffer from rust but there are certain areas that should be inspected closely. Front wheel arches are part of the bolted-on front wing and are relatively easy to change if rust has overcome them.  At the time of writing, used front wings are in plentiful supply.

The same cannot be said of rear wheel arches which do unfortunately suffer. You will need to look for signs of bubbling or rust around the rear arches and around the bodyshell just above the level of the rear bumper. Repairs here can be costly depending on how far the corrosion has spread..

Underneath the car, repairs are often needed to the floorpan directly underneath the drivers and passengers footwell area. Look for signs of welding work – most commonly a rectangular “patch” around 11in x 8in. The cause of the issue is water leaking into the cabin, and being trapped by a steel plate under the carpet. Check the floor carpet is not feeling wet in this area.

Exhaust System

Not a huge problem – the factory system is good quality steel and all components of the system are easy to source and install. If you detect a “blowing” sound it is likely to come from a catalytic converters (there is one on each side of the engine), and these have a tendancy to rot on the bottom edge.  A brand new genuine catalytic converter may mean having to re-mortgage your home, but luckily there are plenty of “aftermarket” products on the market which are much more reasonably priced and seem to perform adequately for the emissions test at MOT time.

Wheels

The good news here is that all factory wheels for the XK8 and XKR are strong, and it is unusual to find any serious issues such as cracks in the back of the rim, or buckles. The wheels do ofcourse suffer the same cosmetic issues as any alloy wheel can. Light grazes from kerb damage or paint bubbling can be repaired inexpensively by any alloy wheel specialist – just make sure they get the correct shade of silver paint finish. Supercharged cars equipped with the 20 inch BBS wheels look great, but these are more expensive to refurbish and can be tricky to “split” (the titanium bolts holding the wheel face to the barrel are nerve-racking things to remove – you have a much bigger job on your hands if any snap in the barrel). The stainless steel rim protectors are very easy to catch on a kerb and any damage stands out. Rim protectors are available from various sources priced from £100-£130 each.

Brakes

Brake Calipers and Discs

Standard brakes are generally reliable but do not have the best performance, particularly on the very early cars which use a 305mm disc on the front axle rather than the 325mm fitted as standard from around 1999-on.

TIP:  you can easily upgrade the braking system on the front wheels of early cars by fitting the brake calliper carriers from  a 325mm car. The brake caliper remains the same, so all you will need is 325mm discs and matching brake pads.

Brembo brakes look great behind the alloy wheels but the discs have a tendancy to “warp” causing brake pedal judder. It is quite feasible to upgrade any standard to Brembo but the sets are highly sought after. Expect to pay £1000-£1500 for a kit.

Anti Lock Braking System

A weak point, especially on 4.0 models and especially so the 1996-1997 model years (VIN numbers 000001 through to 018107). The ABS pump is bolted to the ABS electronic control module. The pump and module are electronically connected via a chunky twin, insulated wire – and the soldered joint on the wire on the circuit board inside the module has a tendancy to “go dry”. This is a simple enough fix if you are skilled with a soldering iron but you will need to carefully cut open the casing of the factory sealed module. More detailed information on this procedure can be found on most Jaguar forums. Alternatively, plenty of specialists offer a repair service (one of the most reputable being ECU Testing in Heanor, Derbyshire).

Suspension

Rear subframe must be inspected for rust. The large “plate” (known as the “A-Frame”) holding the differential will have rust. It will be difficult to inspect this if you don’t have a lifting jack available, and at the time of writing (2019) there are replacements on the market, whether is it a good condition used item or a refurbished and powder-coated or wax-oiled part. It is also unlikely that the seller will be happy for you to start tapping the plate with a hammer to check if it is solid, but it is an important check to make. Most MOT testing centres will fail a car if the subframe shows evidence that welding work has been carried out in the past.

Interior

Switches and Controls

A regular fault of the XK8 is in the Indicator stalk. Regular use of this part seems to take its toll, so when the ignition is on and vehicle stationary test all functions from sidelight, dipped headlights, flasher, main beam and turn signals, in particular ensuring no other lights come on or go out when they shouldn’t.

The centre console switch panel has a design flaw, in that the switch “guides” often warp from heat, causing the buttons to either stick on or off. This is particularly common on the Hazard and Traction Control buttons. Make sure all buttons perform as expected. A replacement is £100-£200 second hand.

Backlight bulbs on the Heater Control panel buttons usually fail and are easy to replace but the panel assembly must be removed from the dashboard to do so – about 30 mins work. The LCD display has two backlight bulbs so if one half or the whole display doesn’t light up then you will want to fix this. But any black “blobs” or liquid “bleeding” in the LCD display will not be repairable, and a new panel will be required.

The drivers window and mirror switch is worth checking on all functions. A replacement will be £40-£60.

Seats

Check the operation of both front seats. The seat control module is a weak point and although it is a very easy part to change, they are expensive – especially so on 2001-on models. Both front seats use an identical control module, so in the event of a problem with the drivers side module you can swap it over with the one on the passenger side, or vice versa. Seat switches are the next weak point but these tend to suffer more from physical damage i.e broken control tabs.

Later cars which have a separate headrest regularly have a broken headrest height adjusting mechanism. To change this you will need to remove the leather back rest, and this means the plastic back-release tab needs to be removed. The plastic tab will be old and brittle, and will almost certainly break when you try to remove and are now obsolete from the dealer making replacements bloody hard to find. For this reason most owners choose to live the problem.

Wear on the leather, especially the drivers seat “bolster” is a problem and most cars over 60,000 miles will be showing wear. The best solution is to find a seat cover from a country with the opposite drive side – so if for example you are in the UK (right hand drive) look to buy from a left hand drive European market such as Germany where the Right Hand seat is the passenger seat.

TIP: On early cars (1996-2001 with integrated headrest) the seat backrest leather covers are the same on both sides, giving you a better chance of finding a suitable replacement locally.

Electronics

Most important check of all is the remote central locking system. If the remote fob will not communicate with the car this can be very expensive to fix, especially so on 2001-2006 cars (VIN numbers ranging from A11050 through to A48684). The ECU controlling this is no longer available to buy new and a used item is priced between £200 for an early Coupe model up to £700+ for late Convertible.

Steering column “reach” motor is a common failure on vehicles with electrically adjustable column – this can be dangerous in some circumstances as the steering column can be pushed or pulled in or out while driving. The motor itself is unlikely to be the issue, rather the steel cable linking the motor to the column gearing which can get “chewed up” and prevent normal operation. Relatively easy to change by dropping the steering column down. Replacement part cost is £60.

“Cruise control not available” – if you see this fault appearing on the dashboard it can be something as simple as a brake pedal switch fault.

TIP: You could test the brake pedal switch using a multimeter. Just locate the electrical plug – of  the four pins, the two outer pins are for the brake lights and gearbox interlock circuit and will “make” the circuit when the pedal is depressed. The inner two pins are for the cruise control and will “break” the circuit when the brake pedal is pushed. Any fluctuating readings or resistance in the circuits will cause a fault.

On early cars (up to 1998 for XK8 and 1999 for XKR) the cruise control is operated by a vacuum system, and the most common issues are broken pipework (an easy fix) or faulty/stuck vacuum solenoid valve (inexpensive).

Now for the bad news. On models equipped with “Adaptive” cruise control this could be a very expensive problem. These models have a radar-type of sensor unit located at the very front of the car – just behind the front bumper skin. Failure rate is quite high unfortunately, and we are unaware of any simple “fix”. We are regularly asked if it is possible to revert to standard “non-adaptive” cruise control but this, at the very least, would require different brake servo and master cylinder, dashboard instrument pack, steering wheel controls. We have not experimented with this and know of nobody who has tried. The unit is, at time of writing, no longer available to buy new.

Air Conditioning

All XK8 and XKR models are equipped with Air Conditioning as standard. The system is easy to check ofcourse by setting the temperature control to its minimum 17C and putting the blower on full speed. If a satisfyingly cold air stream comes out then you can assume the system is OK.

If nothing comes through, you could test the system pressure (albeit in a rudimentary fashion) by depressing the pressure valve in the front right corner of the engine bay (located on top of the receiver drier bottle) – however we are going to state clearly here that WE DO NOT RECOMMEND THIS DUE TO THE HARM THAT COULD BE INFLICTED IF THE GAS IS INHALED. By using a metal rod (screwdriver for example) press the valve very gently – if a pressurised jet of gas comes out then the system is holding pressure, and there will be a fault somewhere on the system.

If the system is empty, the most likely cause will be a hole in the air conditioning condenser, which fits in front of the main engine coolant radiator. These are not too expensive to buy brand new, but are time consuming to install due to the need to remove the bumper and drain the coolant system. Realistic parts and labour cost to replace the condenser is £350-£500.

Airbag System

Airbag system faults, indicated by the yellow warning light remaining on or flashing on the instrument cluster, are not a common problem. It is safe to say that if the car does have an airbag warning light on, and the seat is of the type that has a separate headrest,  then the fault will nine times out of 10 be caused by the Occupancy Sensor in the passenger side front seat. This is a gel pad which fits directly under the leather in the seat base. Changing it is a bit of a chore and involves dismantling the seat base. If you do the job yourself you will need to perform a “Hard Reset” on the battery to clear the fault.

LPG Conversions

There are several companies out there who specialise in converting Jaguar cars to run on LPG. If you are considering installing LPG then we would recommend choosing an installer with a wide experience of Jaguar models. One of the most reputable is K Mugglestone and Co of Boston, Lincolnshire.

If buying a car with LPG already installed, look to see if it is a neat and professional looking job. For instance, loose wiring that has no cable clips could show that the job has been done on a budget at home. Badly mounted Electronic Control Units, or a switch in the dashboard that has been installed with no thought or care for aesthetics, can all be tell tale signs of an unprofessional job.

The obvious disadvantage of an LPG system is the need for an LPG fuel tank. The only option is a “donut” type tank to fit in the spare wheel well. This will leave you needing to keep the spare wheel in the boot itself, and even though the XK8 boot is a good size the spare wheel will take a sizeable portion of this.

There is no reason that an LPG system would cause any problems, but we would have to state that a far higher proportion of V8 cars we see with head gasket failure are those that are fitted with LPG systems. Again, this would be another reason to consider an experienced installer.

Performance Upgrades

XKR owners can get a notable performance gain by installing either a smaller pulley on the supercharger, or a larger pulley on the crankshaft. Each of these modifications has different characteristics.

There are several independent specialists you can go for further advice on both minor or major upgrades, such as:

• Design XKR, Andover
• Elite and Performance Jaguar, Derby
• Swallows Independent Jaguar, Weston-super-mare

In Conclusion

Hopefully this buying guide has not been too exhaustive and will be useful to any prospective buyer. There is a lot to take in, but these are complicated cars that, like any other classic car, have niggles and issues that over time have been exposed through normal usage. The XK offers excellent value and good reliability, and can be maintained on a reasonable budget. If you have any questions, or think we have missed anything, please don’t hesitate to get in touch.

Thank you