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Jaguar XJ6 S3

Top Cat Published: 25th May 2011 - 0 Comments - Be the first, contribute now!

Jaguar XJ6 S3

Fast Facts

  • Best model: 4.2
  • Worst model: 3.4 auto with cloth trim
  • Budget buy: None in particular
  • OK for unleaded?: Should be okay
  • Will it fit in the garage? (mm): (mm): L 4927 x W 1727
  • Spares situation: Mainly good
  • DIY ease?: In the main pretty doable
  • Club support: Typical Jaguar
  • Appreciating asset?: Appears to be for best ones
  • Good buy or good-bye?: A good one is the best XJ6 around
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The S3 is the best XJ6 of them all - so buy one while it’s still great value

Pros & Cons

Jaguar style, luxury, usual XJ ambience, S3 improvements, value for money
Many poor ones around, major rust woes, V12 running costs, high prices for top ones

Back in the late 1970s many people believed that the world’s best saloon car wasn’t the Mercedes S Class, or the Rolls-Royce Silver Shadow, at all. They thought that top honours went to the Jaguar XJ6-12 range instead. Whether badged as Jaguar XJs or Daimler Sovereigns and Double Sixes, their unique combination of silken mechanicals (especially the V12), outstanding ride comfort, handling poise and sheer good taste were regarded as truly world beating at any price. The car’s fi nal fl ing, the Series 3, was the original blueprint at its most stylish and accomplished best. Perhaps it was the Arthur Daley association with the car in Minder but, for all its qualities, the S3 has strangely slipped under the classic car radar for far too long and, as a result, it remains astonishing value for money. But it can’t – and won’t – stay this way for much longer.


S3 was first time an outsider reworked a jaguar

As the 1980s loomed, Jaguar had been tarnished by the travails of its parent company British Leyland. During the mid-1970s Jaguar build quality was dire with the S2 (and the XJ-S), even though the design boasted worthy improvements over the original XJ6. Jaguar’s reputation by the mid decade was slipping badly. The XJ40 replacement, fi rst thought about in 1972, was still almost a decade away, so something had to be done to stop owners deserting for a more trusty German rival. The answer was another, but far more substantial makeover, in the shape of the March 1979-launched Series 3. Italian styling house Pininfarina was involved in this budget £7m project and – apart from past styling concepts – it was the fi rst time that an outside company had ever laid a fi nger on a Lyons cat. Essentially, the XJ remained much the same but the chunky facelift made it seem far more major and modern. Those big bumpers were squared off and given crash damping, the tail lamps were restyled, the roof was raised and fl attened, the glass area improved and the door handles recessed. These changes made it look like a brand new car. Mechanically, fuel injection was grafted on the old 4.2 sixes – V12s were already injected by then – while the entry level 3.4 stuck with twin carbs, but now boasted a slick shifting Rover SDi fi ve-speed gearbox instead of the heavy old overdrive transmission set up.
There were assorted suspension and running gear upgrades to keep up with those Continental counterparts, too such as retuning the suspension to accept modern tyres. The interior was subtly upgraded with new seats and the roof was, quite literally, raised, to quell criticisms of the lack of rear headroom that had always plagued the car. Crucially, Jaguar had a serious go at sorting out the build quality woes with good success.

As a result, demand, especially in America, shot to unprecedented levels. When the six-cylinder cars gave way to the XJ40 in 1986, they were still riding high. Due to Jaguar making it almost impossible to fi t a Vee engine in the XJ40, for fear of BL insisting on the Rover V8 being used, the lovely old V12 had to survive until 1992. Soon after launch, the 4.2 XK engine received a modifi ed cylinder head and cams, while the V12 gained the acclaimed Fireball head design, to aid economy. For 1982 the Jaguar also became a Sovereign featuring Vanden Plas-like appointments. Other than these, further changes remained very few before the S3 was replaced by the XJ40. The V12 had to live on for another fi ve years and so gained modern essentials such as anti-lock brakes and a better Marelli ignition system, to replaced the ‘opless’ Lucas Opus system that had a passion for packing up.


Despite BL’s interference, Jaguar’s engineers lost none of their touch and, even on a limited budget, brought the ageing XJ up to date with the S3. “No other car made combines such performance with refinement” hailed Autocar in 1982. Three years earlier Motor felt that the 4.2 was a thoroughbred, “in fact one of the few jewels the British motor industry has left to show the world.” Almost 30 years on, little has changed and there’s still few fi ner ways to travel. True, the interior is typically Jaguar poky, and the boot laughably limited, but the grace and pace is still in there in strength. Jaguar has always been picky over tyre choice and Browns Lane went to great pains to re-engineer the chassis to accept Pirellis, over the original low-profile Dunlops which Jaguar felt had indifferent build quality leading to vibrations. In today’s terms, the XJ’s steering is void of real feel and the handling seems soft, but driven like most classics are piloted, it still feels special and highly rewarding. One road test judged that this Jag was more quiet and comfy than a typical lounge at home! The V12 is a magnifi cent mile-muncher, the base 3.4 with its 162bhp far more sedate, but it’s a sweet, low-revving unit that’s ample for cruising around. However, most will be happier with the far brisker 4.2, which will be equally ‘frugal’, yielding around 20mpg. “Most drivers on their fi rst acquaintance must love the air of luxury, even of the ‘base’ Jaguar…”, said Car in a three way comparison against a Mercedes and a Saab. It went on to praise the comfort, “The Jaguar is at its best on poor surfaces, where it not only soaks up all the shock but does it so quietly”. However, the magazine countered this praise by reckoning cabin space and the heating and ventilation fell well short of 1983 standards. Maybe, but they’re all understandable agerelated defi ciencies that we can happily live with, taking as compensation the XJ’s many qualities that still shine, plus that sheer sense of occasion only a Jaguar can provide.


With its better brakes, returned suspension and – on the 4.2 – larger valves, sportier camshafts and fuel injection, the S3 is the best sorted XJ of them all. As a result, further improvements may not be necessary, if the car is set up properly by a good Jaguar specialist. Even if keeping the car standard, invest in an uprated radiator and a modern electric cooling fan on all models. On the V12, obtain a new electronic ignition to replace the old Lucas set up as the fi rst step for power and reliability. There’s little point in trying to make the 3.4 much faster because you’re better off going for a good 4.2 engine – this engine can be bored out to 4.5-litres, by the way. Speak to a Jag expert about further mods for road use, which don’t effect the XJ’s lovely drivability. Ditto the suspension, where stiffening it up for a sharper feel will kill the car’s lovely ride, if done wrongly. Apart from a full four-wheel geometry check, pay attention to the tyres, as many XJs run on second rate rubber which no amount of tweaking and uprating will compensate for. If you want to go further, contact Berksbased KWE. It produces a raft of mods for the S3, such as a four-speed auto conversion, or a six-speed manual (£5-6000). Better brakes can be fi tted (from £300) and up to 50 per cent more power. KWE can also make you a ‘new S3’ to your taste, if you wish. Call 01635 30030 or click on


Like all XJs, the S3 lags a long way behind the previous iconic Jaguar saloons like the Mk2 making a good one quite exceptional value. This model slots in between the S1 and the S2 in terms of prices and desirability. Condition is everything with this Jag, because there are lots of so so cars around. It’s better to go for a superb, cloth trimmed 3.4, than a mangy, if more prestigious, member of this cat family. As a guide, decent S3s start from around £2500 upwards and £5000 buys a top cat. The 4.2s and the V12s are worth about the same - say £3000 for a satisfactory example and the best can command up to £8000. We’ve seen some truly lovely cars top the fi ve fi gure mark. These are exceptions but, as a rule, fi ve grand is ample to buy a very nice S3.

What To Look For

  • Rust is the bugbear of all old cars, and this Jaguar is no exception. But, if the S3 XJ lacks the build integrity of a Mercedes-Benz, it’s actually very solid and there’s a good chance of getting a ‘clean’ car. Don’t be deceived by gloss, though because there are plenty of dolled up examples ready to trick you.
  • Check the car’s structure with care. Look for rotting fl oors, crumbly footwells and crusty inner wings and structures. The most serious areas concerns the transmission tunnel, where it meets the fl oor, and the rear suspension mounts. As on the earlier XJs, S-Types and E-types, the latter can literally rip themselves from the car under power.
  • Take your time checking underneath and, if possible, have the car raised and supported for a good look. Of course, there may be previous patchwork repairs and this is okay if done properly. Beware, however, of fresh underseal – and owners reluctant to let you carry out such a serious search…
  • Watch for headlamp surround rot, and milkiness in the windscreen corners. S3 screens were bonded in (the fi rst time for a Jaguar) and, with time, condensation works its way between glass and metal, so oxidising the windscreen pillars. Sometimes it’s with terminal results so look for bodges.
  • Bulkhead rot can be a big problem on the XJ, and it’s diffi cult to spot, particularly on V12s, thanks to their crammed in mechanicals. Look at the panel that supports the radiator and the bonnet hinges at least.
  • Other hardy perennial rust points also include the bottom trailing edges of the front wings, sill edges and door bottoms. Rear quarter panels can go crispy in a major way too.
  • Panel supply is indifferent. New front wings are available, but fl itch panels for the rear arches will probably be aftermarket and this area is a corrosion trouble area, along with the rear skirt. The panelwork between the twin exhausts can go frilly over time, as can boot lid extremities.
  • The twin petrol tanks are trouble areas – and no we don’t mean affording to fi ll them up! Petrol is quite cold and so it produces condensation on the tanks. You then get dampness between the tanks and the body, with obvious results. If you lift the fuel fi llers and fi nd rot beneath them, this is the cause.
  • Those lovely looking interiors should be in good shape but may not be. Not half as durable as a BMW or Merc, XJs can suffer from age-related problems of cracking woodveneers, hardening leather, failing stitching, torn trim, and soon. Drooping headlining is an age-old Jag problem and it can take a professional trimmer to put it right.
  • Mechanically, these cars can cover enormous mileages if properly cared for, but will punish skimped servicing. And, as these cars have gone through the ‘banger era‘, many will have been neglected. Check to see if some form of service history is still present.
  • The S3 Jaguar used the ‘long stud’ XK 4.2 unit but it wasn’t the sturdiest of XK engines, thanks to broken studs, failing head gaskets and even the block’s liners going wonky. The chief cause was internal corrosion, where lack of quality anti-freeze lead to furred up water channels. The factory improved matters in 1982, but the only real cure of a pro-rebuild and that can become costly.
  • The 3.4, which is a downgraded 4.2, has a block with more meat on it and is not so susceptible to this problem, although the cooling system must still be kept in tip top shape.
  • Overheating problems with Jaguars isn’t as bad as their reputation usually suggests. Proper maintenance (good hoses, regular flushing etc) helps, of course. Did you know that cheap thermostats can cause hot running, since they are often of an incorrect design? Check!
  • Typical XK engine wear points are rattly timing chains and over silent valve clearances – the latter meaning they have closed in service. It’s a micrometer and re-shim job to do properly, best carried out as part of a comprehensive top-end overhaul, frankly.
  • A fuel injection system was employed on the S3 4.2, while the 3.4 ran on carbs. The V12 had its own set up – Bosch D-Jetronic, before going digital when the HE engines surfaced.
  • The 3.4 holds few issues, other than the usual wear, plus out of balance carbs. The auto choke (never an old Jag strong point) can play up, but manual conversions are available – or you can simply fi t a switch to cut it out when needed.
  • The fuel injection systems don’t like neglect; gummed up work, deteriorating high pressure hoses and dicky electronics/wiring can all conspire to give hard-to-trace troubles. It won’t be cheap mind, as it’s said that simply renewing the fuel lines can cost around £500, to do it properly with OE spec items. So, beware of cheap bodges!
  • At the other end of the combustion cycle, look for similar cheapskate repairs to the exhaust. As you can see by looking at the system, there’s a lot of metal there, which can rot and need replacing. Which works out expensive.
  • Check oil levels. Lack of lubricant could be a warning sign of internal wear. Check for oil smoke on start-up and when driving. When the car’s hot, lift your foot from the throttle for a few seconds then accelerate smartly. Oil smoke could indicate worn cylinder bores or valve guides. This applies particularly to the venerable XK sixes. When warmed, oil pressure should be at least 40psi at 3000rpm on this engine.
  • The V12 can last forever, if cared for, but watch for signs of skimped maintenance as they remain complex things to look after properly. It takes a day to change the plugs (you have to shift air con pumps, etc) for example, so fresh plug leads and caps can hide ancient spark plugs. Oil pressure should be 60-80lb.
  • They leak oil of course, from cam boxes and, on the XK, from the rear crankshaft oil seal, which is an engine out job to fi x. The usual trick is to not top the engine up to the ‘full’ mark.
  • See a car started from cold. Does it smoke (caused by ’box breathing problems if left standing for a longish period) and clatter? Is the three-speed automatic transmission (a GM Hydramatic400 box, in V12 form) sluggish when fi rst used? Fluid leaks aren’t unheard of, but these units last well if they’re properly lubricated and fi lters are changed.
  • The BW 65 gearbox used on the XK series is also sturdy, but common to all are failing rear mounts, which allow the box to move slightly and cause a knock.
  • Talking of knocks, the drive train should be checked on a test run. The driveshafts double up as part of the suspension on the IRS and they wear, if not greased as part of the detailed service schedule.
  • The rear axles are sturdy and a limited slip diff was a popular fi tment. Listen for undue noise or failing clutches – it’s an expensive expert repair. Leaks from the differential spewing onto the brakes is quite common on IRS suspended Jags, plus the diff can actually work loose and cause a ‘clunk’ under acceleration.
  • Manual XJs are pretty rare fi nds. It used an adaptation of the Rover SD1 unit, before being replaced by a Getag design during the mid 80s. The former can be easily rebuilt, unlike the German ‘box where spares have become virtually non existent, it’s claimed. Clutch care is straightforward although, like all Jags, are heavy duty and time consuming to replace.
  • The inboard rear disc brakes are a famous Jaguar horror story. Unless someone has chopped an inspection hatch in the boot fl oor (not unknown), you have to work from under the car to change the brake pads.
  • The rear subframe is encased in rubber bushes, to give that legendry refi nement. Expect them to be worn, or perished by now. Changing them isn’t the easiest of jobs but it’s certainly rewarding, since a tired rear end can lead to ‘rear wheel’ steering. Rear geometry is critical and usually incorrect on an XJ; you need a good Jag bloke to set it up right.
  • The S3 enjoyed some of the best brakes found on a Jaguar. Four pot and ventilated, they are up for the job, even if the engine is modifi ed, although will be dear to replace if tired, not to say long winded due to the need to strip the rear end. The handbrake is typically old Jag Rubbish in other words, and could well need overhauling to pass the MOT. The handbrake has its own, rather feeble little pads and calipers, all tucked completely out of sight. These are awful to work on, often neglected!
  • The electrics are another weak area, with a lot of problems caused by the wiring failing under engine compartment heat, especially on the V12s which really hot up. The infamous Lucas OPUS (’opless’) electronic ignition is best replaced by a modern set up because it’s bound to fail at some point.
  • Other sparky problems include lethargic starter motors on V12s – and they are a sod to get to – plus defective central locking and electric windows. So check everything works okay.
  • Don’t forget things like tyres. The S3 was specifi cally engineered to run on Pirelli rubber of 205 or 215 x15inch size. You can still get the Italian tyre in 205 size, but Michelin is the only other quality company dealing in 215 rubber. Cheap second-rate tyres on XJ6s are very common and it spoils the car.
  • Finally, let’s talk gift horses. Condition is everything with this car and it’s better to go for a fab 3.4 (manual with cloth trim) rather than sad Sovereign, for example.

Three Of A Kind

We’re talking about the Silver Spirit and the Mulsanne respectively here; same car with different trimmings, although the Bentley is the sportier pick, especially in S and Turbo forms. A real improvement over the previous design dynamically, they can be exceptional value for money but there’s a lot of dolled up cars on sale. Post ‘84 cars are better made and had a lot of the earlier gremlins eradicated.
Mercedes S Class
Mercedes S Class
Along with BMW, Mercedes, with its E and S Class models, was the strongest rival to the Jaguar, especially in terms of build quality and durability. Dynamically, they were aheadof the older Jaguar, but are not as quite or comfortable, plus lack the emotional feel that’s essential in a classic. There’s a big choice, however, and they sell for peanuts, while spares are still available from main dealers.
BMW 7 Series
BMW 7 Series
If ever there was a modern ‘sleeping’ classic cruiser, then the 7 Series surely qualifi es for the role. Stylish, exquisitely fi nished and with some superb engines, the BMW is an excellent car and with an expansive line up of power units, starting from a 2.8-litre which is not overly expensive to run. There are plenty of BMW specialists but spares and repairs can prove more than the car’s real world worth.


Forget the unfortunate Arthur Daley links, the S3 is without question the best XJ6 of themall. A good one makes an excellent classic choice, for a fraction of what a Mk 2 will cost. But, there’s an awful lot of dross out there too, so drive a few to gain datum. A good example will make you wonder why you left it so long to own one. As Car said of the S3 back in 1987, when it was getting long in the tooth and already replaced by the XJ40; “It’s an old car; perhaps that it is why it’s so good.”

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