XJS Quick Reference Buyer’s Guide

2016-01-18 Read: 439x

By Doug Dwyer

The purpose of this guide is to briefly outline some important purchase considerations, to answer the most common questions relative to used XJSs, and to illustrate where a used XJSs is and is not different from an ordinary used car. It is not intended as an in-depth history of the XJS nor as a general "How to buy a used car" checklist.

Feel free to ask for more detailed information in the forum section below.

Are some years better than others? Which do I avoid?

We must take into consideration that, the oldest XJS is now 35 years old. Any that are still on the road have survived the test of time. Actual present day condition and the type of care they have received is more significant than any original quality and design issues.

XJS production ended in 1996 so even the last cars are quite a long way from being brand new and some are at a point where time and mileage might have starting taking a toll. Still, though, the 1994-1996 cars, especially those with the 4.0 engine, are often considered the best of the bunch due to their luxury features, build quality, and reliability.

Will I have reliability problems?

Quite possibly you will, yes, especially with the older, higher mileage examples. Many XJSs have not received proper care and some have been outright abused. And, truthfully, these are not drive-it-and-forget-cars even under the best of circumstances. Some owner involvement will always be needed. For most Jag enthusiasts this “involvement” is part of the fun.

To be totally honest if you’re on a tight budget and/or don’t have DIY skills, buying a 14-35 year old used Jag is probably not the right decision, especially if you buy a ratty example at the low end of the market.

That said, the typical scenario is to spend a few weekends and a chunk of cash sorting out all the problems and routine servicing that the previous owners have neglected to address. With a bit of effort, time, and money you can have an XJS that is easily reliable enough for daily use.

What about electrical problems?

The stories you’ve heard have basis in truth but most Jag enthusiasts agree that they are grossly overstated. Most of the electrical problems can be fixed by cleaning grounds and connectors and replacing fuses. The Lucas starters, alternators, and relays are high grade and as long lasting as any other. Lucas manually operated switches on these cars tend to be lower quality. Many of these items can be opened up and repaired.

The mid-90s models have significantly upgraded electrical systems with corresponding improvement in reliability.

Are they DIY friendly? What about parts?

Most repairs are well within the realm of a typical experienced DIY mechanic. The more difficult repair areas will be mentioned later. Parts support for 80s to early 90s vintage models is generally good. Parts unique to the 70s vintage cars are becoming scarce and, oddly, the last-of-the series “facelift” models from 1992 onward are likewise suffering from parts availability issues. Trim and cosmetic parts can be very expensive on any of the variants but many mechanical parts are surprisingly reasonable.

I should add that later models became increasingly complex. Starting in late 1988 more equipment was added year-by-year. ABS brakes, air bags, security systems, motorized seat belts, and a full host of electronic luxury features. It’s not that these later cars should be avoided, as that’s not the case at all. However, additional equipment can add expense and detract from ease-of-repair.


The XJS was built with either a 6 or 12 cylinder engine. The 6 cylinder cars, however, were not common in North America until the introduction of the “facelift” XJS in 1992.

The 5.3 /6.0 litre V12 is a great engine and nearly indestructible unless overheated. They are definitely more complicated, expensive, and time consuming to work on. For this reason they’re not for everybody. For those not easily intimidated, though, they are a joy to own and drive. The “HE” V12 was introduced in mid’81 and provides much better fuel economy than the earlier engines...which were notorious gas guzzlers. The 6.0 litre V12 is a real powerhouse, by the way.

The 3.6 and 4.0 litre six cylinder engines are both good and are not likely to cause any grief although some of the older 3.6s could easily be ready for a head gasket change or perhaps even full overhaul by now.


About 350 pre-1980 V12s had a manual transmission. All other V12s used an automatic transmission: the Borg Warner BW12 until mid-77, then the GM TH400, and then the GM 4L80E behind the 6.0 litre versions. All are good transmissions but higher mileage cars might be due for an overhaul.

A fair number of 6-cylinder cars were built with Getrag manual transmissions, very few of which ever came to North America. Those with automatics use a ZF unit. Both are good and neither present any unique problems beyond typical age/mileage considerations.


Four wheel discs on all models. The fronts present nothing unique. The rears, however, are inboard mounted until 1993-1994 when a conventional outboard system was used. Replacing pads on the inboard brake system is easy but replacing rotors, calipers, and axle seals is very labor intensive. Proof of replacement of these items is another “plus”. Watch for rusty/contaminated fluid on cars that have been stored for a long time.

Repairs on the later outboard rear brake system are routine and no more difficult than any other car.


Very rugged and long lasting unless the above mentioned axle seals haven’t been replaced and the unit runs low on fluid.

Virtually all XJS had limited slip differentials. High mileage and/or hard driven cars may have worn out limited slip mechanisms.

Wheel bearings

Conventional in the front but the rear wheel bearings are rather tricky to install and set-up properly, especially on the inboard brake cars. Check for excessive should be barely perceptible.

Cooling system

Nothing exotic or remarkable on the six cylinder cars.

The V12s have a complicated cooling system that must be kept 100% up-to-snuff. No exceptions. I cannot stress this too much. Neglect can be disastrous to the V12 engine. A well kept cooling system suggests the seller knows about Jaguars and a savvy owner will be happy to boast about how well he cares for the cooling system.

When road testing a candidate car keep an eye on the coolant temperature. Anything above the “N” or mid-point of the gauge is cause for suspicion and requires further investigation.

If you hear wild clattering from the engine then it has been overheated and the valve seats have dropped. Run away from the car.

Climate control

All models used a fully automatic climate control system. Repairs here can be labor intensive and expensive. A fully operational climate control system is yet another “plus” when considering a used Jag.


One of the best parts of the car and part of what makes a Jaguar famous. All candidates would be of the age where bushings and ball joints will likely need replacing. Most of this work is DIY friendly except lower control arm bushings on the front suspension, which are labor intensive. Again, proof of repairs in this area is something to look for.


These cars are built like tanks but even tanks rust. Watch for rust in all the lower body panels and floorboards. Also check the underbody for rust where the rear suspension radius arm bolts to the body. Rust here is a major safety concern. From a purely practical perspective only the rarest variants and most exceptional examples of these cars have enough value to justify the expense of rust repairs.

Front and rear windscreens are somewhat known for leaking so look for damp carpets and moisture behind the dashboard.

Fuel system

Fuel tank rust is a potential problem on all XJSs especially if the car has been stored for long periods.

Fuel odor in the trunk/boot is a fairly common issue and can be caused by a leaky tank or weeping hoses. This problem can be difficult to solve. Even a minute leak can create a strong odor in such a confined space. An odor free boot is a real plus when considering a used XJS.

Fuel hoses in the engine bay, especially on V12 cars, are subject to heat deterioration and must be replaced every few years. This is a very important service requirement. Proof of hose replacement suggests the owner knew how to care for his XJS.

All XJSs are fuel injected and over the 21 year production span several Lucas/Bosch systems were used. Detailing potential problems for each system is beyond the scope of this article. However, none of the variants have serious design flaws and all work well but with age and mileage some repairs will likely be needed.

Ignition systems

The early V12s used an OPUS ignition system which doesn’t have a very good reputation. Upgrades and retrofits are common on the “OPUS” cars.

Beginning in mid-81, simultaneous to the introduction the upgraded “HE” V12 engine, the Lucas CEI (Constant Energy Ignition) was introduced and is considered a vast improvement over the older system.

Seized/inoperative mechanical and/or vacuum advance systems are common with the Lucas CEI distributor. Checking for this during a typical used car inspection is not practical but asking the seller about it might give a clue as to how the car was serviced.

Later V12s used a Marelli ignition system which can be very problematic if neglected. Worn parts can cause an entire bank of cylinders to stop firing. Unburned fuel then accumulates in the catalytic converters causing them to overheat. Actual fires have resulted from this.

In a very brief nutshell the Marelli system is fine if it is properly maintained. Check invoices for replacement of the distributor cap and rotor, spark plugs wires, and spark plugs. This work is expensive so it is often put off....until it’s too late. Proof of proper Marelli care is another “plus” and suggests a savvy owner who knew how to care for his Jag.

The Marelli system was introduced at approximately at VIN 157116 which corresponds to mid-1989 model year in North American terms. Identifiable features include two coil wires in the top of the distributor cap, two square control modules on the radiator upper mounting panel, and absence of a vacuum advance canister at the distributor.


Paint jobs and rust repairs are hugely expensive, as is new leather, wood, carpet, and chrome. If these things are important to you, find and pay for a car that needs little or no work in these areas. Many Jaguar projects are abandoned when the owner is faced with spending thousands....many thousands.... to make the car look as good as it runs.

Pre-purchase inspection

Having the candidate car checked by a professional is usually well worth the money. Ideally a veteran Jaguar shop should be selected as they’ll know exactly what to look for. However, even a regular repair shop can check the basics and hoist the car for an underbody, brake, and suspension inspection.

Price vs. Quality

These cars can be bought for surprisingly little money. Do plenty of shopping around to get a feel for the cars and the market. If your goal is a Jaguar to really be proud of and enjoy, it pays to wait for the “right car” to come along and buy at the higher end of the market. This is almost always cheaper than buying a scruffy car and bringing it up to the same standard. With used Jags, finding the right car is more important than finding the right price, within reason of course.

If your goal is a project car you’ll have plenty to choose from. There’s great satisfaction in returning an old Jag to its former glory. Just be aware of the expense involved.

Hopefully some of your questions have been answered and you can shop for your dream Jag with a bit more knowledge and confidence.

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