The Jaguar V12 is the most reliable v12 ever put into large scale production, and by the time it was discontinued it was made in far greater numbers than any other manufacturer had. It is a very strong and reliable engine. The troubles come principally when the ancillaries, including the under bonnet loom, electrical items and rubber parts are not replaced when they are at the end of their life. These items are not "fit and forget" because the heat generated by the engine cooks them after (say) five years or so.


Therefore regular replacement of hoses, HT leads, plugs, dizzy cap and rotors, suspension rubbers, are essential to keep the car as factory. As far as I know, these points apply to all Jaguar V12 engines regardless of age that were fitted into XJSs. There being no great difference between the 5.3 and the 6 litre versions from the reliability point of view.
Greg

 

Well put Greg.

I'm no mechanic, but I have always loved the Jaguar V12. It seems to me that people expect a 'commercial engine' from Jaguar. No V12 is a run of the mill engine. It's exotic! They are all monuments to automotive genius and we mere mortals should show them respect. I mean if you own a Germanic or Italian V12 you treat it with the respect it deserves so should those with an British one. These remarkable objects of the engineering art require proper care.

If you want a pair of Mickeys on a beefy rear end good for you, just make sure your flannelette shirt is clean and at least coordinates with your lumps Connolly hide interior - you'll be the chief bogan of the 'hood' in no time.

but please remember the words of the great man himself
"GRACE space and pace" not "Fishtails, Burnouts and AccaDacca"

AND YES TONGUE IS FIRMLY IN CHEEK! (i like ac/dc )

 

I had a 90 XJS Convertible. The engine really wasn't that hard to keep going. Everything else had it's moment with me, but the V12 Started everytime and never left me wanting other than some occasional vapor lock in the summer. The cooling system seemed to run a bit warm (above the H) which it wasn't supposed to do in Summer. I spent a lot of time trying to figure that out.

I have my eye on a 95 Six cylinder. Took it or a test drive. It ran great and upon getting into the car, I could see and feel a lot of refinement over the 90 model. I think by then Jaguars were getting built "Ford Tough". I'd love antoher V12, but thought I'd try the 6 cyl for a bit.

Tony

 

Yeah, the 5.3 V12 is mostly let down by the transmission. Shift it yourself and it helps, but still, that transmission is a HUGE disservice to the car (other than the smooth shifts - but have you driven these underpowered Mercedes with 7 speed transmissions lately?? almost makes up for the lack of power).

Given that even a 6L drivetrain can be picked up for less than $3k - it seems the best bet would be to buy an 89.5 (in black on black, the best XJS possible), twin turbo it, and drop that in your black on black 89.5.

Yes?

 

OK, I've read the entire thread, and I'll bite. I'm new here, so bear with me.

Going back 5 pages to the original post, wasn't the question relating to the differences between the '95 and '96 models? And weren't they in essence the same? Were there any differences at all between '95 and '96?

I'm looking at two cars right now. A '91, and a '95. Re-reading this thread, it shouldn't be much of a choice. But it still is:

On the credit side for the '95 is the better drive train. Both engine and transmission. That, and "end of the line" refinement. Also, the 16 inch tires are easier to find, and they would be stock. On the debit side, I prefer the rear tail lights pre-facelift, and the two seats vice four, and I know the car I'm thinking of could use some paint. Overall, I think the earlier cars look "lighter". The car I'm looking at does have a rear wing, which while aerodynamically is about as useful as a wet roll of toilet paper, does have the advantage of improving the looks of post-facelift taillights.

On the credit side for the '91, we have what I think are better looks. Believe it or not, I find the idea of inboard brakes appealing, in a challenging sort of way. I like the two seat configuration. Both cars have airbags, but the '91 only has a bag on the driver's side, and I'd consider removing it for a different steering wheel. Before that sounds too outlandish, after 25 years, the bag needs to be "refreshed" anyway. On the debit side are hard to find 15 inch wheels, which means I will have to pay for a wheel upgrade, less refinement, and of course, age.

Applicable to both are plans for a new exhaust, engine "tweaks", and a conversion to a manual transmission. If I can figure out how to connect a speedo to a 3.31, that would be preferred, failing that either will end up with a 3.54. Price for either car is about the same.

Thoughts on this? Does the 6.0 liter outweigh the credits of the '91 by that much? Is pulling the back seat that unreasonable? Unlike those who add "ground effects", I'd rather make the car look "lighter". I will be doing all my own work, as I live in a part of Texas where a local collision shop wouldn't work on replacing the front bumper on a Boxster, as they don't work on "exotics". I have some experience, but am by no means an expert.

 

I'm biased as the owner of 1990 Convertible (there were no 1991 models in California), and would always prefer the best and last of the pre-facelift cars. So much so that I would never buy a facelift car regardless of price or driveline.

With full deference to our fellow forum members who love their '92 and up cars, they just aren't why I continue to keep my XJS long after I thought I would. They prefer theirs and I give them full props for that. However, why I love my '90 is that I get to drive a "classic" car, but with nearly all the modern bits needed for a daily driver -- EFI, Electronic Ignition, ABS, etc.

The most frequently asked question I get is "what year is your car?", and when I answer, they always get a confused look on their face. They are always expecting it to be a more a classic vintage. So it's a perfect combination of classic looks and modern motoring.

99.9% of the population wouldn't be able to tell the difference between a 1975 and 1991, but most could tell a '91 from a partial or full facelift if they were parked next to each other. The entire point of the facelift was to modernize the looks and bring it up-to-date to extend the production run. It was an deliberate effort to "declassify" a dated design.

The later cars are 'better' in many ways, just as a Series 3 E-type is better in many ways, yet the Series 1 is the most sought after. There is no doubt that the Series 3 XJ is the best, yet if I were going to buy one today it would be a 1973 or earlier Series 1. It's likely a matter of my heart versus other's heads.

IMHO, in the long-run the 89-91 Convertibles will be the most sought after out of the larger production models. They aren't the 'best', but they will be the most desirable.

But like I said, I'm more biased than Donald Trump at Comb-Over Contest.

 

Edelweiss
If you are going to put in a manual box, the diff ratio on the later car is much more suitable. The 6 litre engine, especially in US spec, is definitely more powerful than the US spec 5.3. Also the electrical looms are better quality on the later cars, but they do have more electronics, such as electronic boxes as part of the window operating system and central locking system etc, while earlier cars are 100% electric rather than electronic. The 16 inch wheels on the later car are a huge advantage, and many pre facelift owners, including me, have fitted them.

I actually agree with Mac about the pre-facelift being the better looking car, but if you have no strong views on that score, go for the later car, say I. Nice problems to have though!
Greg

 

i was talking with a classic jag parts dealer, just couple day ago.

he was surprised that i had a good running Black Bumper car(his words not mine)1978 XJS, he said prices are finally going up on 70s Jag XJS, if in good condition!

i sure like the idea!

 

If you do not get some pleasure out of working on cars, then I would stay away from Jaguar and any other car of 20 year vintage.

First things to do if you get it are possibly replace all the hoses, if they are original. Check the wiring in the engine compartment. Specifically the fuel harness. Replace the radiator or have it recored. Thats what I would do.

If I buy any old car, I replace CTS, TPS, IACV, MAF, all the relays (even though they are bosch for some reason they just dont last long (the holes in the bottom of them cause them to get corrosion I believe). Get sealed relays. Just buy them in bulk and leave extras in the trunk. I used economy relays off ebay and they have been rock solid for 5 years. They were the sealed ones. If you do one of the above, definitely do the relays. I have owned several xjs cars from 91-95 and they ALL had relays go bad at different points. Now I just swap them all out first thing. I also go through each connector and put dielectric grease on them, after spraying clean with wd40.

Back to your question, for what you are getting for your money, and if this is a fun car, then get it. If its going to be a daily driver, like mine are, you really should do what I mention above. A lot of guys here may disagree but I just like to not worry... I have had just about all those parts mentioned go out on all my xjs, that were purchased 2010 and on.

 

Now that I acquired a very nice 1996 XJS with 10.444 miles I will be looking for a 1995 XJS V12 ...
I read all your comments and have decided to look for one.


The hunt is on...Wife does not know yet.....

 

The 6.0l XJR-S may have been fitted with three speed auto box but the 93 to 96 XJS 6.0L had four speed auto (GM 4L80E) fitted to all.
As others have said I would expect 5.3 V12 to beat AJ16 powered xjs to 60mph and 6.0l with four speed box even faster acceleration

 

V12 or go home

I came across a few nice 6 cylinder examples whilst lookign for my XJS. Although tempted, they did not have the same allure. I eventually came to the conclusion that if I'm gonna buy an XJS, I'm gonna buy the proper one

 

You used my quote and then did not answer the quote. Just be straight up when you talk about owning a XJS V12 as to how much time and money you have into the car to give any perspective buyer a true picture of what they are getting themselves into.

Personally I could care less if you own a Prius or a V16 Bugatti Veyron as long as you give a honest picture of what it takes to maintain and own that vehicle on these forums. It is only fair to any perspective buyer to get a honest and fair take on ownership and not just talk about " allure " or what ever the catch word of the day is.

Truth be told whether you are talking about a V12 or inline 6 cylinder XJS neither is what I would consider a sports car and since most V8's can run circles around them why not get the XJS that is the best fit for you.

Happy to hear you found the V12 that fit you best but to say things like " V12 or go home " is just irresponsible to any perspective buyer who is looking for honest feedback. Now I am going to go out and drive my very reliable and low maintenance AJ16 - enjoy your time working in the garage on yours-LOL !

 

I love spending the time on my XJS, everything that I have worked on to date has been independent of the V12 engine though. Undoubtedly I'll get to that (I want to do some cooling overhaul), but the issues I have/had are not V12 specific. They are likely more specific to any 25 year old car...and anyone buying a car that old should know the reality.

Even if you buy one of those XJS' with half it's intended cylinders (.. JK.), you will have lot's of love and care to give to the car, as you would any other car designed in the 60/70s . It's also the V12s that are seeing the biggest value increase.

Best,

 

Now we are having a thought provoking conversation. I never said the Jaguar V12 is poorly engineered. I do feel that the V12 in the XJS is a tight fit and therefore creates issues as far as access and heat goes.

We all know that getting to things on the V12 in the XJS's tight engine compartment is at best a challenge and at worst a nightmare for the non mechanics among us. I worry about those that are not mechanics or are not given a clear understanding of what owning a XJS V12 entails will find themselves facing at times.

The worst situation I can imagine is someone buying a car like the V12 XJS who is not a mechanic or simply wants a fun pleasure car who has no idea or a false impression what it takes to get a V12 XJS up to spec and maintain one year after year. Many have become disillusioned and or financially strained trying.

The other issue that is a factor in owning a XJS V12 is heat build up in that tight engine compartment. Excessive heat is hard on engine hoses, wires and accessories and so this requires a more hands on experience when it comes to XJS ownership. I think Jaguar missed the mark by not venting the hood on the XJS like they did on the E-type hood.

Does no one any good if a perspective buyer decides to purchase a XJS not having a clear understanding what they are getting themselves into. Conversely, nothing better if the right person buys a XJS and has a great experience owning and taking care of one of these finely crafted gems. This is why I feel it is only fair and responsible to give an accurate picture of what we all deal with owning and maintaining the XJS in all it's forms.

As far as V12's having the biggest value increase well this can be looked at a few different ways. First, when you are at the bottom it is only up from that point. Second, gas prices are at a 10 year low so it makes sense that more can afford to drive the XJS V12-LOL!!!!!

 

The V12 does bring challenges and isn't the right choice for everyone. That's for sure. But, for that matter, any Jaguar might not be the right choice for everyone. For that matter, any 15-20-30 year used car might not be the right choice for everyone.

That said, and to be 'straight up', I can honestly say that in my years of XJS ownership the V12 engine itself was the least problematic part of the experience. I DID do the 'usual V12 stuff' right off the bat (cooling system overhaul, injector wires, etc) but then it was smooth sailing. Climate control, power windows, differential overhaul, transmission overhaul, seat heaters, ball joints, steering hoses, subframe mounts, etc. all took up far more of my time, effort, and cash than the V12 engine did.

OTOH, my AJ16 powered XJR wasn't exactly a pleasure cruise the entire 140k miles that I drove it. Multiple ignition problems, water pump failures, idler pulleys, crankshaft balancer failure, cracked exhaust manifolds, throttle body clogging, and so forth.

I wouldn't recommend any used Jaguar to a person who doesn't have deep pockets or who doesn't take pleasure from DIY repairs.

Cheers
DD

 

Speaking of being honest, do you own a V12 as well as AJ16 engined cars? Or are you just opining on the V12 without any first hand knowledge?

I've owned both for quite some time, and contrary to popular opinion, the AJ16 is the only one of the two that proved to be unreliable at certain times over their lifetimes.

The AJ16 cars also had many more annoying failures, like failed steering wheel adjustment motors and memory modules, but that's not engine related so I wouldn't count it against the engine itself. Everyone assumed that getting access to the Ford parts bin was going to improve reliability, but that's also turned to myth in the real world. Ford outsources part building to the lowest bidder like every other mass produced car in the world and they aren't intended to work 25 years later.

In the case of either engine, it isn't the engine itself that is generally the cause of reliability issues. It's relays, wiring, sensors, perishables not replaced in a timely manner, etc.

Greg in France said it best above, <i>"The Jaguar V12 is the most reliable v12 ever put into large scale production".</i> The AJ16 engine is good, but I doubt anyone is going to argue it was the most reliable 6 cyl. engine ever put into large scale production.

My real life experience with both engines, is that the V12 would outlive the AJ16 with proper maintenance. Without proper maintenance, the AJ16 is more tolerant of neglect over the short haul.

I guess it's a shame that Jaguar never put a simple diesel engine in the XJS, then it would be super low maintenance and reliable. I wonder why nobody ever lumps an XJS with a 4 cyl Toyota diesel engine...?

My advice to anyone considering an XJS is -- don't.

*Unless* you are interested in learning about all the quirks of the car, and you are willing to learn how to work on the car yourself. Doesn't matter whether it has a V12 or 6, the quirks are coming regardless and they'll be cost prohibitive relative to current resale values if you have to pay someone to do the work.

Cheers

 

I think you've given a very good, concise summation.

I particularly appreciate this passage :

"....the quirks are coming....."

Cheers
DD

 

Thanks Doug,

We were obviously on the same page, because we both have experience with the merits of both engines (for me two V12s and two AJ16s).

 

Well good I have awaken the V12 lovers out of their sleep. Makes me smile when one of you makes a comment like " V12 or go home " and none of you answer that with something like " cool your jets V12 lover ,that is not the only XJS made or The 4.0L is half the cylinders yet offers comparable performance to the 5.3L when you consider HP, weight and gearing ".

I have several friends who have the V12 and so I am not just speaking from hearsay. Wisdom comes from watching others struggle and learning from their mistakes so I can honestly say I learned from their struggles with the V12 and figured out I would rather have the 4.0L.

Speaking of being honest have either you or Doug owned a AJ16 XJS or are you both going to give examples from a supercharged AJ16 XJ6 or talk about failed steering motors and memory modules on a VDP that is not on the XJS that I have.

Oh and your remarks on the Jag V12 being the most reliable large scale production V12-news flash there really has not been that many large scale produced V12's in car history to compare it to but there sure has been a ton of inline 6 cylinders mass produced. Just because one of you makes the remark that the Jag V12 is the most reliable mass produced V12 ever produced does not make it so.

I guess I need to go back and rewrite the history books with a title like " Jag V12 owners that replaced your V12 with a Chevy V8 after having one problem after another- Your bad because the Jaguar V12 is the most reliable mass produced V12 ever produced ". Give me some of that Kool aide cause it just has to be true.

Speaking of experience how many miles does your V12 XJS have and how many miles on your VDP AJ16 XJ6? Since you made the comment that from your experience the V12 would outlive the AJ16 with proper maintenance I am curious what real experience you have to make that comment.