12cyl reliability

[John Vudmaska]

I just got a 77 xjs i have heard stories about
the un reliable 12 cyl mostly from non jag people
are they really reliable and what do you do to
make them reliable if not
thanks
John V

 

[Claymore]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by John Vudmaska:
I just got a 77 xjs i have heard stories about
the un reliable 12 cyl mostly from non jag people
are they really reliable and what do you do to
make them reliable if not
thanks
John V<hr></blockquote>


The V12 is very reliable, provided you maintain it properly (the cooling system in particular).

 

[Jeff]

I own an 85 and have had extremely good luck with it. Cooling can cause serious problems but correctable by common sense and a good maintenance program. Best advice I will give is if you experience performance or heating problems, shut the car off immediately and rectify the problem. Your car is 26 years old and will undoubtedly have problems with belts, hoses, oil leaks etc. Again, it has been my experience many of these problems can be traced to too much heat under the hood. Still, the car (engine) is not a Ford or Chevy and you need to be willing to spend considerable extra time and money in repairs and maintenance. How much is anyone’s guess. An engine rebuild can easily cost $6,000.00 and, as you are likely aware, a fair running 1980’s XJS may cost you half that. The lesson being, you have to love these cars to justify their ownership. Some owners have replaced the V12 with an American V8 ( I believe the car is then deemed a “lump”). I personally would prefer to leave my car as it is, but any time the issue of changing engines is raised, it incites volumes of heated emails which to me only demonstrates the extreme passion the owners of these machines feel towards them.

There is an excellent website on Jag-lovers that discusses their inherent problems. https://forums.jag-lovers.org. There is also a free downloadable compilation of owners repair tips maintained by an almost mystical guy named Kirby, whom I, among many others, would deem the patron saint of the XJS.

 

[Steve]

I owned a 1976 XJ-12 in the UK, the 40th made with fuel injection. The car was absolutely reliable, with the only problems being associated with the ignition amplifier. This was mounted in the centre of the 'V' of the engine block, and as it was sensitive to heat, tended to quit. Once allowed to cool down you could be on your way again, but the only long-term cure was to replace it. There should be kits available to allow mounting of the unit on the front shroud panel as per the later cars, if this has not been done already. Otherwise, check the oil level religiously every day, change oil and filter every 3,000 miles, check the coolant level when you check the oil, maintain the coolant at the recommended concentration, change every two years. Basically if you follow the factory recommended schedules all should be well. Keep an eye on belt for tightness and condition, always keep an eye on the temperature gauge.

If you have a good 'un it should stay that way. You can never be sure how a previous owner treated the car, but if it is fine now, it is easy to keep it that way. It's a beautiful car, you're a lucky man. Enjoy!

 

[John S Farrington]

You have a unique automobile and the engine is a great piece of work. All the previous advice I agree with including the added expense of the extra 6 cylinders. I would not say that the V12 is a source of unreliability. The greatest source of a series 2 unreliability is the quality influence of the British Leyland ownership of Jaguar during the series 2 design and manufacturing. This has influence particularly on the series 2 electronics. The trim and finish flaws that Leyland was responsible for have probably been worked out on a well maintained car this old. Dont expect good gas mileage on this car because it is prior to the HE modification to the cylinder chamber in 1982. Good luck and enjoy the unique car that you have.