1984 Jaguar XJS 5.7 V12 from North America


Was a pain, but is now reliable


When I got the car, the owner had just put a new gas tank in, because it was leaking, so it had a gas smell, but I took it out with a mix of putting charcoal and a couple of apples in the trunk.

Also when I got the car, the radio did not work well. The tape player was messed up, and the preset buttons stuck. So after three months of dealing with this, I pulled it out and installed a Pioneer Premier radio, which cost $360 with a five year warranty for the radio. Along the line, I installed a Jensen 600 watt HLX amp with four SPL 6X9's and one Infinity Lappa Perfect 12' sub woofer.

About eight months after I had the car, something went wrong with a valve or a cylinder, which no one knew what was wrong. Not even the Jaguar shop, and my dad, being a trustworthy person, believed them on many things, and ended up wasting about $1600 on trying to fix this engine. In turn, I got angry and pulled the car out of the shop, and took it down to my grandpa's, since he has about every tool imaginable, and pulled the engine out (note to all who decide to do this; you will find your Jag engine has more junk than most Buick's, and are about as tight as a diesel to get out; suggestion, have a lot of patience, and with a few cuss words here and there, you've got it made) and with the purchase of a conversion kit for $1500, I put a Chevy 350 engine in the car, and it works properly now.

Now it's nine months, and I'm starting to think the speakers in my car are messed up and are wearing out, so again I will be installing new speakers soon.

General Comments:

The car was fast, but now it is faster. Plus it still steers like a dream.

The old engine, I sold to someone who wanted to use it as parts, so I have a little bit of cash in my pocket, and I'm happy to get rid of the engine, and I'm thinking about upgrading my amplifier to a Memphis Belle one of these days.

I never liked the backseat; no room at all. My fiancee can't even fit back there, and she is petite, but hey, fixes the problem with the sub woofer, and other speakers that you can't put in the trunk due to the gas tank, so what I did was put my sub between the driver and passenger seat, and mounted the four 6X9's onto the sub box, and ran the wires from the amp in the trunk to the speakers in the backseat.

Also, about the new engine I put in it; could I get a few words on what to put on it to make it faster? I'm getting different opinions on this.

Would you buy another car from this manufacturer? Yes

Review Date: 21st June, 2004

30th Jun 2004, 07:42

What a shame you have destroyed a lovely british classic by messing about with stereo systems and sticking an american engine in it. You appear more concerned with the amount of power the boogie box kicks out than the engine. Please do not get me wrong, I am a big fan of American cars and their big V8s, but feel that transplanting these engines into a jag negates the whole point of having one, why not just buy a mustang or something?

I have an early XJS (1979) V12 which has never given any mechanical trouble - although the electrics are as usual full of gremlins. The engine in this pulls like a train, is quiet and smooth, if a little thirsty and has the potential to tune to racing car spec (TWR got 700BHP plus out of their 6Litres)

Anyway, enjoy your jag, at least it will be cheaper to service and repair now! (and it won't break)

1984 Jaguar XJS 5.3 litre from North America


A standard of luxury and performance no other car company could even come close to


Well, I have a heating problem. it likes to get Really warm really quick, but that's expected with a V12, and the interior is in ruff shape, but I haven't put that much money into it I've only had to replace the starter.

General Comments:

I have a sports tuned transmission and this car can move if I put it down, I highly recommend getting the transmission tuned up, it makes that V12 act like its suppose to, havn't lost a race yet.

Would you buy another car from this manufacturer? Yes

Review Date: 23rd May, 2003

17th Jun 2005, 10:54

Very short review, but I am interested in the transmission tune up for better performance, have not heard of that before.

6th Jan 2007, 21:42

If you have an overheating problem, you must fix it immediately or your engine will die (actually, you'll drop a valve seat and your mechanic will not want to deal with the extra labor involved in getting the head off these). These engines do not run hot (ever) unless the cooling system is in need of maintenance. The "hot running V-12" myth is just that. They run at 94C. That's hotter than a Chevy V-8, but not all that hot. The thermostats keep them at correct temperature provided the rest of the cooling system is in decent shape. Some morons actually put cooler thermostats in, thinking that this will "fix" an overheating problem. It won't. The correct temperature is 94C. This is the designed temperature for maximum power and efficiency. If you put in cooler thermostats, the car will run cooler (with less power) longer, but once warm, or on a warm day, the car will overheat. This will happen until you fix the cooling system.

Usually, the radiator is blocked and usually, the owner can't face this simple fact. Even a partially blocked radiator will send the temperature through the roof. I cannot emphasize this enough. Aftermarket fan assemblies will not fix a blocked radiator and the original equipment is more than adequate for racing applications.

Also, this engine cannot tolerate being run hot. Aluminum engines must never be allowed to overheat-not even once.

You cannot neglect the cooling system in this car. I have owned enough of these to know that the temperature gauge rests 1/2 to 2/3 of the way between C and N in a properly operating engine. Any higher is too hot. BTW, you can run these at 120 mph ALL DAY LONG and never get outside this range. If you can't, your cooling system needs work. There is nothing wrong with the DESIGN of the cooling system or any of it's components. This is another common myth.

Most used V-12 XJs need a new radiator because of bad factory maintenance that stipulated adding Barr's Leaks to the cooling system. They're all clogged with this garbage from the first owner (who took her to the dealer for maintenance). Do a complete cooling system flush. Twice. Then change out the radiator and install original thermostats and gaskets. Remember that this is a very unique engine. It has probably the highest compression of any factory engine made, it advanced the art of fuel injection and requires careful attention be paid to its operating parameters.