Otto: I got your PM, hadn't had a chance to respond as I have been busy. In the interests of time, I'm going to cut and paste earlier posts on the same subject that I've made.
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I've heard that there was a period where jaguar reliability was total CRAP? true? if so, what year range?
BAD year ranges for Jaguar XJ in the US: 75-82, 88-90, 98-Early 00 (V8 engine chews up cylinders and dies - only fix is new engine - if car has replacement engine, should be fine)
Good years: 82.5-87, 95-97, 03.
Okay years, some well known problems: Late 00-02 (timing chain problems - factory fix kit available, brings it up to 03 timing chain standards; costs about $750-1000 to have dealer install it)
Your best bet is a 95-97 XJ. The 95-97 cars don't have quite all the gadgetry of the later V8 cars (they have an I6, a blower I6, and a V12 as options), but their electronics systems are simpler, there's less to go wrong with them, and they're actually better to drive. The I6 is a much stronger, much more proven engine than the V8, and the transmissions behind them are stronger as well, even though they are four speed instead of five. There is no significant difference in fuel economy, and the non-blower cars are only 40 horsepower less compared to the regular V8. The blower sixes have an even better transmission than the blower eights, and they're only down 50 horsepower - something easily remedied with a pulley and a chip. They're also stupidly cheap - under $6K for a normal XJ6 in excellent shape with low miles, $10-15K for an XJR (which is interesting, since that's MORE than what a 98-00 XJR can be found for.)
The 95-97 XJ actually had better initial and long term quality ratings than the LS400 of the same years. That's bloody impressive, and no Jaguar has managed to do that since. IMHO, the 95-97 XJ is the best sedan Jaguar ever built.
If you need any other Jag info, just ask.
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In the US, the 87 is my car, the Series III. The 88-94 is the next car, the XJ40. Unfortunately, it has LOTS of problems, especially in early models. If you wish to buy an XJ40, buy a 93 or 94. They're just as cheap, and they have all the fixes, so they're actually pretty reliable.
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There aren't any big nasties on the X300 (95-97) XJR that I can recall. It's probably the best car Jaguar ever built, fully the equal of a Lexus LS400/430 in reliability.
The water pump tends to go around 150K, the cooling fan motors (electric) go at about the same time - both easily replaced. The ABS accumulator tends to be problematic at about 100K, but the car will tell you about that and it's not fatal or hideously expensive. The transmission is from GM, so it will last nearly forever and if it dies you can get that serviced cheaply just about anywhere. There are no core engine problems with the AJ16 engine used in the X300.
The only external problems to watch for are rust around the wheel arches and around the radius arm mounts, and around the top of the trunk cut. They're far less susceptible to rust than anything prior from Britain, but their sheet metal is on par with BMW - so watch for rust. If you see severe rust around the wheel arches, plan on some expensive rust repairs, or just walk away. If just minor rust, it can be caught and remedied more economically - but you must catch it before it gets nasty. This, of course, applies to most modern luxury sedans, so it's not exactly Jaguar specific.
On the interior, the clock/temperature LCD display(s) in the center stack tends to either lose its backlight or have the display go blank entirely. Relatively easily fixed; lots of good used ones out there. The cupholders in the armrest are fragile and tend to break with age. Repair is, again, easy and relatively affordable. The only bit of ugliness is the automatic steering column - I don't know where they sourced it, but it likes stripping the teeth off the nylon gears in the electromechanical gearbox inside it after a while (80-120K). Not all that hard to fix, but a pain at the wrong time. The workaround is to set the column to manual, not auto (it moves up and forward a bit to let smaller people out of the car), or to get the gearbox replaced with a stronger one out of a late X308 or X100. There are also some retrofit kits to remedy this with improved parts. This does not cause the steering wheel to go unstable or flop around when it fails - it just simply stops moving around and is no longer adjustable.
As with all supercharged cars, check engine compression and leakdown before purchase. If the supercharger is in need of replacement (it's technically a wear item, but they don't seem to wear out on the X300s or X308s), it's the common Eaton M110 unit, commonly found on *many* Ford SVT cars and in the aftermarket. Other than the above, almost nothing goes wrong with the X300 XJRs - which is why I'd like to add one to the collection.
On the test drive, there should be no weird noises from the rear end, there should be no ticking from the engine (though clicking fuel injectors are both normal and OK), and it should not visibly burn oil. If it is visibly burning oil, walk away, someone did something stupid with boost and caused premature engine wear. The temp needle should sit almost precisely in the middle of the range, perhaps a needlewidth towards cold. If it runs any hotter than midway without flogging, then you may have cooling system issues - such as a clogged radiator. Uncommon, but it happens when some idiot who used to have a Series III doesn't bother to read the X300 manual and dumps Barr's Leaks into the cooling system as a preventative measure. It's not a fault of the car, but a fault of the owner.
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I have a few more pics of the XKR, I'll post them below.
It's been fairly reliable, with one big exception. Not quite on par with, say, the Lexus SC430, but I'd put it up against the best the Germans churn out in terms of electronics and most of the drivetrain.
Unfortunately, that exception would be the engine. The 1997-2000 V8 engines were not the happiest things ever to roll out of Coventry. They had a Nikasil cylinder lining on the normally aspirated cars that didn't work out so well, and many of them have a timing chain problem which if left unchecked will eventually break and trash the engine. The timing chain problem was partially corrected in late 2000 (mine is an early 00), and truly corrected in 2003.
I *thought* my car had the 2000 fix, as it had a notation in its service record that seemed to imply it. Unfortunately, it didn't, and the engine ended up killing itself. If I'd known it needed it, I would have gotten the timing chain and tensioners (the problem parts) replaced early at a price of ~$750-1000 USD and been able to drive it nearly forever. Instead, I got to buy a new engine - but it looks like Jaguar/Ford is going to end up reimbursing me for it.
Don't let that scare you away from an otherwise good V8-powered XJR or XKR, though. Just be advised to NOT buy one from before early 2000, and if you get one made before 2003, have the 03-up timing chain and tensioners installed immediately.
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That should sum it up for the XJ and XK right there. And like I said earlier, feel free to ask any more questions if you want.