- Feb 8, 2014
- Houston Texas
- 1998 Lincoln Town Car Cartier
Spectre, if you're going to make comments like that, it would help if you had some experience with the cars you're talking about.
I'm Spectre's V12-loving friend. To give you an idea, I have owned 6 XJSs myself (two '82s, and '83, two '85s, and presently a '92). First off, I feel it is necessary to point out that there are many people out there who are still driving these cars as reliable daily drivers. I am one of them. It is not my only car (primarily because I need a truck with 4x4 as well), but when I was in college, my '82 was my only car. I drove 35,000 miles my first year of college with it. It never once let me down, and this was on a car starting out with 130,000 miles on it, ending with 165,000. Calling these cars unreliable and having a lot of problems is due to either not having any experience with them, or having experience with an idiot mechanic. I've worked on over 75 of these cars as well when I was a Jaguar mechanic., and probably a total of 150 differen Jaguars of all kinds made from '79 onward. Some earlier ones, but I don't deal with those as often.
To make a few corrections to Spectre's comments: The V12 is notorious for its dropped valve seat problem. This is not nearly as likely to happen as people say it is. I have severely overheated V12s, and have never dropped a valve seat. I am honestly not sure what exactly causes people to drop valve seats with these cars, but as far as I can tell you really have to overheat the thing very, very badly. Also, when it does happen, it requires removal of the cylinder head but usually you can get away with just having the head repaired and putting it back on, if you find a machine shop experienced with such repairs. The biggest problem I have noticed in terms of items getting cooked is the rear o-rings on the GM A6 AC compressor, however on the 6.0L cars that was replaced with a Sanden. The cars made '91 and earlier had fuel hoses connecting each injector to the fuel rail. Those hoses have been known to crack and have fuel leaks, causing a fire. This is mostly due to idiot owners who don't change the fuel hoses. 15 years later, they catch fire. Gee, what a concept. If you don't replace your fuel hoses and they get very dry and brittle after 15 years, they may leak. Starting in '92 this was resolved with a better design in which the injectors clipped right into the fuel rail, much like most other cars. I have not noticed a need to change belts or hoses any more frequently than I would on any other car.
The biggest issue that Spectre (almost) correctly identified is what was known as the "Marelli failure." '89.5 was when the first Marelli cars came out. Then through '95, the V12s were cursed with this ignition system that actually divided the engine up into two banks. The problem with this design is that the ignition cap and rotor are not that great. The rotor specifically will fail in such a way that half of the engine doesn't get spark. This is fine, except that the (now hot) catalytic converter is getting pumped full of combustible air and unburnt fuel. If you don't catch it quickly enough, it can set the car on fire. I had this failure happen to me about 2 months back. It is very obvious when it happens, the car loses power completely. To not have to call a tow truck, simply keep a spare cap and rotor (with appropriate tools) in your trunk, so you can change it yourself when it happens and be on your way. Sometimes one of the ignition coils fails, as well (there are two), but that is rarer.
It should be noted, though, that in the 1 year and 10,000 miles I've driven my '92 XJS since I bought it, this was the ONLY problem I've had with it, period, and if I was more diligent I would have changed them early. I am looking at dumping the whole system for a MegaSquirt & EDIS setup anyway, but that's another story.
The 6.0L cars are better. They seem to have a better cooling system, they have a Sanden AC compressor and more modern accessories in general, and they seem to get up to operating temperature faster. The big thing, though, is that they make a lot more power and torque. However, the 6.0L cars still had the same Marelli system except for the last year of production. The XJ12 had this distributorless system, but as far as I know the XJSs did not. Retrofitting it is not as simple as Spectre suggests, especially given how hard it is to find. Stick with the Marelli. Just change your cap and rotor yearly.
To be sure, the 6-cylinder cars are less maintenance and easier to work on. They also get (slightly) better gas mileage. The biggest expense in a V12 is maintenance if you need to pay someone else to work on it. Finding a good mechanic on these cars is difficult to do. However if you are willing to learn and do the work yourself, then you'll be fine. Most people I know who own these cars take that route, and it works out very well for them. The saying goes "There's nothing like a 12," and the Jaguar V12 is not only the most reliable production V12 ever made, it is actually just a reliable engine and probably the most streetable V12 available. The only reason I would suggest anyone to shy away from a V12 would be if they didn't have a good mechanic or couldn't find one. Any Jaguar has its eccentricities, though, and you'll need a good mechanic no matter which one you get.
The 6.0L cars came with a 4L80-E GM automatic 4-speed transmission behind it. The 5.3L V12s came with a TH400 GM 3-speed transmission. "The Driven Man" offers 5-speed conversions. I am on my second one (had one in the '82 and now one in the '92) and it is a fabulous upgrade that completely transforms the car.
I would go for the car that was taken best care of that you can find. When I bought my '92, it had 48,500 miles on it and was taken excellent care of by an older gentleman who had a lot of moeny he liked to throw at his car. So, the car basically lived at the mechanic's and came home on weekends for visits with the owner. What that means is that today I have an XJS with 58,500 miles on it that I have had only the one problem of a Marelli failure with. You want lower miles because it means that there is less overall wear on the car, but you also want one with a detailed service history that involves a lot of service. This means that you will then be able to drive it without having to service it frequently. If you drive it a lot (which is what I do) it will give you lots of reliable service. Don't drive it like grandpa - put your foot to the floor and let that V12 scream up to redline! It's good for it, I'm not joking. These engines do carbon up, and the "Italian tune-up" is the only way to keep that engine clean and running great.
Try not to drive it less than 20 miles. Highway driving (and backroad driving) is best. Spirited highway/backroad driving is better still. I am fortunate to have a 20 mile commute on highways and backroads, so my car gets this kind of use every time I leave my house.
Now, for the general synopsis of years:
'76-'81: Pre-HE. Fuel consumpion is measured in gallons per mile. OPUS (very old) ignition system
'82-'89: HE. Significantly improved fuel consumption with a redesigned cylinder head. Some interior improvements. Rear differential changed from 3.31 to 2.88 ratio. '85 introduced a trip computer. Lucas ignition system (best and most reliable)
'89.5-'91: Marelli HE. Marelli ignition system. Significant interior improvements, plus a minor change in doorhandles. Heated seats with lumbar introduced
Early '92: "Facelift." This was the first exterior redesign to the XJS since its introduction. All 92s had the 5.3L Marelli HE engine, same as the '89.5-'91s. The exterior and interior had major redesigns, however, which included a much different instrument cluster and trip computer. Power seats for the first time. Early 92s still had the older style suspension (which most view as better, including me) with the '89.5-'91 door handles. I have an early '92, and I view it as the best of all worlds, except I do wish I had a 6.0L (but I'm working on that...)
Late '92: Changed to the "XJ40-style" suspension, and door handles changed to a standard flapping type that people can actually figure out how to use. If you buy an early '92 or earlier, be prepared to explain to people "No, you push the door handle UP... no, don't pull on it... no, UP!!!"
'93: First year of the 6-cylinder XJS. Only 6-cylinders available in '93
'94-'96: 6.0L V12! Accompanied change in differential to a 3.54, with a 4-speed automatic overdrive transmission. Exterior, interior, and suspension the same as the late '92 onward.
As for me? I have an early '92 (by choice) with a 5.3L V12 and a 5-speed manual transmission conversion. It will be getting wheels from a '95-'97 XJR and a 6.0L V12 out of a '94 XJ12 parts car that I acquired hopefully over the winter with a MegaSquirt & EDIS to control it.
Hope this helps, let me (or Spectre, who will relay to me) know if you have any other questions.