to get a 1990 xjs convertible in tip top condition, no electrical system problems, no oil leaks, new coolant system, no problems at all. i would like one that i could drive like a gm car.
i just sold my pita xjs convertible and don't want another like it. no more driving and the next time wondering if i will need a wrecker to get it home.
what you say, is it possible.

 

There has to be more wires than there are in the space shuttle, I would love to find one with a Chevy 454 in it.
Honestly, why did Jag need all of that needless wiring. Half the weight is wires, LOL

 

Everybody that saw my 12 cylinder was very upset to hear it was only 262 HP. I have a Honda Valkyrie Motorcycle 6 cylinder with 112 HP. Go figure.

 

Mguar has good notes on gleening more HP from the car.

lots of dead weight, exhaust system is a suffocation tube lots of options to gain 15, 20 hp here and there. I believe all things considered my car should be around 320hp though havnt paid to dyno.

to fully restore a XJS can be pricey if done via a shop, if your just wanting to do it yourself it wouldn't be hard. Just depends on how good your starting point is...complete gasket kits are several hundred dollars, new rad is a few hundred to recore. Spool of fuel hose, coolant kits, sensors all new I could go on but from what I've spent I would say a few thousand in parts to renew much of it.

 

100% possible with a 94, 95 or 96 with the in line 6. Just may be the best cars Jag ever made, even more so with some of of the late 95's and 96's that have the vacuum servo bakes. The Late V12's are very good too but do need lots of heat related maintenance.

I presently have a late inline 6 car with the vacuum servo brakes. Drive is amazing.

 

Welllll......25-30-35 year old Jags will never be a 'drive it and forget it car'. Neither will a same age Corvette, Porsche 911, Audi, Bimmer, etc etc.

But I'd say they can be made to be reliable. I'm on my second V12. Neither ever left me stranded; my present V12 is my daily driver. But, it takes work and patience to get 'em that way and keep 'em that way. Still, problems creep up on my '85. I make a list and tackle them every few months. I have to do the same with my 1995 F250. It's the nature of old cars.

I can't remember the problems you had with yours, specifically, but most old Jag problems are common/typical and most the fixes known.

Personally I think a good way to help ensure happy Jag ownership is to adopt the "do it all, do it right, do it once" philosophy. AFAIC, it's a 'given' that a 30 year old XJS is gonna need a full overhaul of cooling and brake systems, will need injector wiring, lots of vacuum hoses replaced, injectors professionally cleaned, all grounds cleaned, instrument connectors cleaned, diff seals replaced, fuel odor in the trunk fixed, windshield leaks fixed, new suspension bushes and ball joints, etc. Just dig in and get it all done. And then enjoy the car.

Alá carte repairs, a bit here and a bit there, just prolongs the misery.

Cheers
DD

 

Seller's remorse, Mac?

 

Why attached to the 90? Why the v12.

I'm not sure anyone has produced a 12 cylinder car that isn't complicated to own. BMW, Mercedes, Volkswagen, Audi...on top of that, every part on the car will be 30+ years old.

Nothing lasts 30 years without some TLC.

The 6 cylinders are way easier to work on. So much room and access, perhaps you should consider that! I've never had my 96 strand me....except when someone rear ended it! The OBD2 helps speed up diagnosing issues.

Something to consider.

 

If it's power that's desired, check out what Bob is doing to his 4.0 over on the X300 forum:

https://www.jaguarforums.com/forum/x...l-done-238278/

https://www.jaguarforums.com/forum/x...esults-238702/

 

Mac,

I agree with Vee. Buy another V12 XJS if you want a hobby car that can be driven regularly but needs careful, complex and regular maintenance. Buy a late 4 litre if you want the XJS style but with much lower and easier maintenance demands.

I've had my 4 litre convertible for nearly 18 years and the only time it's let me down was during Covid this year when the alternator pack failed after the car had been sitting for 5 months. Apart from that the car has behaved impeccably with a standard preventative maintenance regime.

Now that you've had the original V12 experience, why not go for a very late 4 litre model and have all the style in a much more reliable package?

Good luck

Paul

 

What I miss is the looks of my late 1990 XJS convertible, I used to get it out of the garage, drive it up in front of porch, sit in chair, pour a drink and look at it.
It got to the point, is it going to start the next time or what is wrong now. It was an attention getter, lots of compliments.
It got to the point of being a pita but a pretty pita.

 

The only Jag I ever liked the looks of is a 1990 XJS convertible with the 4 round head lights, never liked the looks of a hardtop Jag.

 

There is a shop in Portland, OR that Turbo'd a 4L 6cly Jag now it wins drift races with a near 1:1 hp to torque ratio about 420hp. They didnt mod much the engine takes the boost quite well.

 

It doesn't have run very well for that :-)

Actually I think that's part of the problem with a lot of these old Jags. They're great eye candy but since the value is so low not many people had the desire, know-how, or finances to really keep up on the repairs and servicing. By the time the third, fourth, or fifth owner comes along....that would probably be you and most of us.....there is a big stack-up of issues there were never attended to.

Cheers
DD

 

This is internet lure. The builder clearly stated the car was not competive but still cool none-the-less. The engine needed extensive repairs and upgrades. Many things needed to fixed. I personally spoke to the owner / builder and he detailed all the things that needed re-engeneering to me over the phone. It was a long chat. I've posted about this in greater detail in another thread about the car. One of his employees posted incorrect info that then engine and down played all the mods and fixes. The owner made an account here and updated the info in the same thread.

If you read the pretolicous article an engine failure was clearly detailed and considerable changes were made.

 

Paul, I do not disagree with the conclusion of your points, but I do disagree with the way you got there!
The only significant difference between the 6 cylinder cars and the 12 cylinder ones is the engine, and the access and quantity differences that brings. 98% of the troubles people discuss on here are not engine related; but are common to both models. Lighting, driveline, fuel pumps, suspension, brakes etc etc. Almost none are to do with the mechanical aspects of either engine. I have had my coupe for 22 years and it has let me down three times:

1. the first when the injector loom shorted out - which, had I known about that problem at the time, I would have preventatively replaced much earlier.
2. a one year old Bosch fuel pump failed
3. a suddenly flat battery.

In terms of what I have had to fix/improve there are lots of them, but that was my choice except for my steering shimmy which in my ignorance I did not twig was a brand new factory diff fitted by me 70,000 miles ago. But this is not a V12 issue, either.
I believe the big cause for V12 problems is access. Things are much harder to see, understand, find and fix under a V12's bonnet than a 6 cylinder car. And although, once you get into it, they are actually NOT more complex, there are lost more things to go steadily through under the bonnet: more hoses, more thermostats, more things in the V hiding the engine, more difficulty getting to plugs, dizzy, senders, etc etc etc. This is the factor, in my view, that leads to the V12 being considered less reliable, because for many owners, it is just too daunting to get the basics done. So they do not get done. Consequently, when someone buys a V12 they do a few bits, but do not to it all. And I acknowledge that this takes determination and a real love of fixing mechanical things - to a degree that many people just do not possess.
On the other hand, the effervescent JOY when a V12 coupe is 100% right on point - suspension bushes, ride height, shockers, engine, gearbox, aircon, interior, AND on a long Grand Tourer type journey - is something that no other car, not even a 6 cylinder version can come close too. And once right, it WILL stay that way.
So you takes your money and makes your choice; as you so rightly say there is a difference, but I submit it is not a reliability issue, it is an effort to get it right issue, rather than an inherent design matter.

 

I flat love the V12 but I need to acknowledge how good the 4.0 six is.
The V12 was started in 1954 as a concept. Finally came into being in the early 1960’s making 508 horsepower out of 5 liters. William Lyons looked at American engine of over 7 liters and recognized that V12s would never get there. So it was re-engineered to allow that. In doing so they switched from a Hemi Head configuration to a Heron head ( combustion chamber in the piston ) both for weight and space savings reasons. That design actually made more torque and horsepower at lower revs than the earlier Hemi head design did. Plus it reduced manufacturing costs dramatically.
First used in the XKE series 3 it originally had been designed using EFI but that wasn’t ready. Having purchased machinery to manufacture the V12 it needed to go into production so they quickly refitted carburetors but to keep them under the bonnet complex routing was required costing about 18 net horsepower.
The V12 was rated in net horsepower ( as actually installed ) giving the impression it wasn’t very powerful. Shockingly that 326 cu in engine made more horsepower than a Chevy 454 rated the same way. And once EFI was introduced to the V12 made 32 more horsepower than that same 454. And 102 more horsepower than a Chevy 350 rated the same way.
But an engine designed in the pencil and slide ruler era was no match for a computer generated one like the 4.0 six.
If you look at the bore spacing and imagine a 1/2 a V12 that is the basis for the 4.0 liters six with the addition of a modern 4 valve system head.

 

From an outside the park point of view. When I purchased my XJS I was totally in love with the thought of the V12, and if I had been able to find a parts car. I would have probably gone with that. Parts availability and cost were prohibitive. (Parts car would have cured most of that.) But I didn't know the hidden problems with my car.
So I've been a member here for many years now, and have read nearly every post concerning the V12 XJS, and then some. The thought of a V12!!! is enticing! The reality of a 30+ year old car with crappy wiring, Ground issues everywhere, and the general decay from lack of maintenance over 30 years, is almost unsurmountable. Especially for most semi knowledgeable weekend warriors. There is simply to much to clean, repair, and upgrade. That as Mac says, it takes all the fun out of it. From all I've read on this Jag's theory, design, and execution. Execution is where Jag lacked in the process. Lousy quality control. Little to no corrosion resistance, I mean the car was built in the UK for crap sakes. Even the wiring harness connectors when pulled apart, have evidence of corrosion on the terminal connectors. American cars don't typically have these issues, Gm has fought lousy ground for years. (ever follow a chevy and when they step on the brakes, the left side goes out and the right one gets bright???) But other then that American cars for the most part have much better wiring. (especially nowadays) Which keeps things working. Which reduces the constant fiddling, and fixing, that has become a staple of owning a Jaguar XJS. Along with the maintenance costs of normal everyday parts. I can see why these cars are not for the faint of heart. But COOL!!! Heck Yeah!
Now to Mac's original question. Which I perceive as What would it cost to Make a 30+ year old XJS Jag Bullet Proof? I'll make an educated guess. Do it yourself 1 year hard labor at $50.00 an hour covers parts, and your labor. at a Shop, 6 months hard labor at $100.00 + dollars per hour. You do the math. Scary!!!

As always just my thought's . I definitely love the V12 at full song!

Jack

 

Jack;
That is the key, parts cars. Turns an expensive part into nearly free. I buy rust free cars for $500 or less. If they are parts cars a tittle isn’t needed, simple Bill of sale will do, have it notarized if really concerned but in my lifetime it’s never been an issue. Same with keys. Sure it’s nice to have a set of keys in case you ever need to rekey yours. But that’s a powerful tool to use to lower the price.
If somebody has gone in and taken the engine apart or whatever the price just got lower still.

If you really want keys and a tittle buy from the insurance sites. You’d be amazed at how many older cars sell for scrap metal prices. Damaged fenders etc. even Engine fires almost alway turn into scrap metal bids. Engine fires ruin wiring but chance are very great nothing else is ruined.

 

I've seen really really nice looking v12 convertibles on line (ebay) for like 15, 16, 17 and 18 grand... Looked like they were kept well. Have you searched...

You should get one! Sounds like you're jones'n...
Which is completely understandable.

Honestly (this is just me - and I'm still new and have a lot to learn) I don't think they are that tough-ah cars to deal with. Unlike my xk8 and 928, I've never run into what feels like a brick wall (fingers crossed and the sign of the cross) or anything unfigurable... ESPECIALLY with all the folks here. The XJS forum is uniquely generous and good hearted. That's just me.

Get one! Ya gotta. Heck with the worry!
What's the worst that could happen?