I have a 1988 xjs with 76 thousand miles, it belonged to my father and he does not know much about jaguar so before giving it to me he started to invent with mechanics who did not know anything about these cars. So the car runs normal with the high temperature, I have already made several changes of gasoline filter, oil filter and manteminiento all good so far but in my country Dominican republic there are no mechanics jaguar specialists there is no head office we have in my country if anyone knows any mechanic or someone who offers to come to change the essentials for the car to run perfectly just tell me to buy and tell me how much it will cost that service including lodging. PS: the car runs very well only outside maintenance of all the electrical and maintenance that the car requires.

 

Everything that's a fluid change it. Coolant, brake fluid, power steering, transmission, engine oil, differential. Change plugs? New thermostat that's tested for proper opening and closing? Change rubber fuel lines in engine bay? Rear IRS rubber mounts? Suspension components like shocks and rubber bushings. Just an idea. Theres lots of helpful stickies at the top of XJS (X27) main page. Start there.

 

Mark has nailed it.

PLUS,
Your market will require 82C stats, NOT the 88 that is often listed.

Read the stickies at the top, beer in hand please, and if more PDF's are needed, ask, I have good few on the laptop, FREE.

DO NOT run it until you are 100% sure that the "hot" temp is false. As overheating, running a V12 HOT, is a death sentence, FACT.

The gauges are a GUIDE, good, and sort of accurate, but not the be all of accuracy.
All mine ran just a tad below the N. It took a while with a master gauge to sort each one. The Blue one only needs 12c rise to take that gauge from under the N, to 1/2 way to H. Its a Blonde, so I let it be.

 

Two points . Filling the radiator isn’t done on the cap on top of the radiator.
Second. The distributor needs periodic lubrication. It doesn’t get it. In the normal fashion.
If the advance mechanism freezes up from lack of lubrication.
The timing is off. Causing overheating.
This is easy to check. Remove the distributor cap. Grasp the rotor, advance it ( twist) and it should snap right back. If it doesn’t that is your problem.

 

All of the above comments are correct. You have a great car but.........you'll need to learn about it and how to do some basic maintenance to avoid big problems. Your lack of local expert Jag mechanic is not an impediment to fun safe operation. Finding this website is your first victory to staying ahead of the game. #1 resource for help and diagnosing problems.
Assuming all fluids are topped off few suggestions in prioritized order:
1. Download or print a copy of "The Book' by Kirby Palm
2. Get a Chiltons or Haynes Repair Manual. Identify various components under the hood and trunk: distributor; throttle tower, radiator; fuel rail; oil and trans dip sticks; battery; grease points; radiator caps x 2 and air bleed plug
3. Fill radiator according to proper procedures to ensure no air bubbles in system.
3.a. Replace Thermostats with 82C as mentioned above and replace hoses to radiator
4. Replace ALL fuel rail hoses and feed and return rubber hoses
5. Assuming your car is a Lucas ignition remove the distributor cap and check to see if the rotor "springs" back when you twist it. (it will only travel about 10-15 degrees). Lubricate the centrifugal advance springs (under the plate) and lubricate the center of the distro shaft ensuring there is some kind of cotton or wool wadding and then use some motor oil to lubricate the shaft.
5.a. Given the age of the car replace the vacuum advance
6. Replace spark plug wires with 8mm thick wire insulation (to prevent electrical arcing)
7. Bleed brakes, check brake pads, replace if necessary
7.a. Given age of car replace flexible brake line hoses: 2x front, 1x rear
8. Remove radiator cover and clean area between radiator and A/C condenser (this area collects leaves and road debris interfering with air flow over the radiator)
9. Grease ALL points. Given age pay particular attention to front wheel hubs; rear wheel hubs; and rear suspension wishbone and half shaft points

As time permits consider replacing front shocks, spark plugs, hoses and belts, new fan blade if never replaced, U/L ball joints

 

This thermostat is what you are referring to? Well right now I'm waiting for the clamps that hold the injectors to see if they work so if you have any link where I can get this thermostat

 

The V12 has 2 (TWO) thermostats, one in th A bank, and the other in the B Bank.

That sticky I mentioned, 3rd one down at the top spells it all out.

Suppliers, ?bay, ?mazon, etc etc, are all you need.

Dealers and other shops are NOT needed. They will have NO ONE old enough to know what a V12 is, and will either NOT work on it, or mess it up more.

You have DAYS of reading before you touch the thing, PLEASE. These are SIMPLE cars, and only screwed up by overthinking things, and allowing Freddy Fiddler near it.

You MUST work to a system, flitting around all over the place is fruitless.

OK, I am downunder, lucky me, and 60 years in the Auto Parts Game, with hands on of a serious nature. I TRUST NO ONE with my cars, ever.
Part numbers I may mention are Aussie related. Clearly available worldwide, thanks to the Internet.

I will get to that PM later, the 300c needs some TLC.

 

Luis
Which country are you in?

 

I believe he's in the Dominican Republic.