What does the temp gauge read in the center position?
Is this the radiator temp or the engine temp?
What temp should I see in the ECU from the OBD port?
What is the factory setting to turn the fan on and off?
The IR gun says the rad is cool 170* and the OBD says 215*
The fan will "some time" stay running for a few mins after the engine is shut down.
Also, I can not get any heat from the vents when the engine is up to temp (215*)

 

So many questions! I don't know the specific numbers, but see if this discussion helps:

https://www.jaguarforums.com/forum/s...rature-186873/

On the early V6 models, there is NO sensor for the coolant temperature. All readings are taken from a single sensor reading the metal temperature of the left (US driver's side) cylinder head.

As for the dash gauge, the needle is centered from approximately 180F through 230F. More details in the thread linked above.

What symptoms are you experiencing? With all your questions I'm guessing you've got a potential overheating issue, but is it an actual overheat or just indication? In response to one question, on a hot day after a long drive, it's not abnormal for the fan to run a few minutes after shutdown. Knowing the ambient temperature would help determine if you've got a problem.

For the lack of heat, go here and run the tests given in posts #2 and #6:

https://www.jaguarforums.com/forum/s...ol-how-185002/

 

Your best bet is to read the DTCs from the climate control module. There are 3 interior temp sensors that can be faulty or fail and cause problems.

The dual heater valve is a known issue.

The good thing about the CYLINDER HEAD TEMP system is that it uses a 'FAIL SAFE COOLING STRATEGY'.

Fail Safe Cooling System
A unique feature of the V6 engine is the use of a fail safe cooling strategy, controlled by the EMS, in the
event of coolant loss leading to rising engine temperatures. The principle of the strategy involves
switching off one or more fuel injectors to inhibit combustion and reduce heat, thus allowing the flow of
ambient intake air to further cool the selected cylinders. By cycling the selected cylinders, ie switching
different injectors off for a period and in a sequence determined by EMS parameters, overall engine
temperature can be controlled sufficiently to allow the vehicle to be driven, at reduced power, for a
short distance. Throughout the malfunction period, instrument panel messages and warnings advise the
driver of the current status of the cooling system as described below.

Driver Indication and EMS Action
The fail safe strategy moves though different stages depending on engine temperature:

¥ Temperatures below 122û C (250û F) are within the normal range. At high temperatures below this
level the temperature gauge pointer enters the red zone.

¥ If the temperature rises to between 122û C - 127û C (250û F to 260û F) no action is taken by the EMS
which affects engine running but the following indications appear:

Temperature gauge pointer in red zone
Message Centre HIGH ENGINE TEMPERATURE
Warning light TEMP
Priority light red
Audible indicator single chime sounded

¥ If the temperature rises to 127û C (260û F) or above, the fail safe strategy operates. At 127û C (260û F),
the EMS will cut out one cylinder (the selected cylinder is varied) and as the temperature continues
to rise, this will increase to a maximum of three cylinders cut (with cylinder cycling). The following
indications are given:

Temperature gauge pointer in red zone
Message Centre ENGINE POWER REDUCED
Warning light TEMP
Priority light red
Audible indicator three chimes sounded

¥ At 166û C (300û F) or above, the fail safe strategy continues as described but the following
indications are given:

Temperature gauge pointer in red zone
Message Centre PULL OFF ROAD SAFELY alternates with TURN OFF IGNITION
Warning light TEMP flashes
Priority light red
Audible indicator five chimes sounded

¥ EMS shuts the engine down.

 

I am thinking that is 300.0*F
That is a wonderful explanation of how the computer-controlled cooling system works

Thanks for posting that description

 

"What symptoms are you experiencing? With all your questions I'm guessing you've got a potential overheating issue, but is it an actual overheat or just indication? In response to one question, on a hot day after a long drive, it's not abnormal for the fan to run a few minutes after shutdown. Knowing the ambient temperature would help determine if you've got a problem."

These temp readings were taken on a "Cold raining" Arizona trip to Phoenix and the wife was not happy with the heater not working!
The Jag was not overheating and the fan did not come on when we stopped that day, but the next day in traffic,(same ambient) and one-stop the fan ran for about 3-4 min!
I did check the coolant level and the bottle was half full when cold

 

Quite often the radiator fans running after the engine is shut off is an indication of a sticking or stuck thermostat.

 

..............so much for new parts!
That being the least expensive and minimal amount of labor I am going to start with a new replacement thermostat
Is there one better than the other?

 

Yes, the best one is whatever is accurate. Or did you mean which brand is best?

Please see my tale of woe, linked above in post #2. After much frustration, I tested 3 thermostats side by side in a pot of water on the stove. The original Motorcraft brand had failed. The first replacement Motorad brand was also defective. I finally got a good one from CarQuest.

What brand to purchase? Except for this one instance, I've always had good results with Motorcraft. And in defense of this failed unit, it was several years old by then. But whatever brand you purchase, test before installation. Test the old one, too, for comparison.

 

"Solid": If you are replacing the thermostat, please also read the various forum posts on bleeding the cooling system once the replacement part is installed, as the early V6 is a right bugger to get all the air removed once a repair has cracked the seals.

Also, just in case you are not aware, mixing the OE specified orange Dexcool coolant with the standard "green stuff" (Prestone, etc.) will result in a chemical reaction that turns the combined fluid into a thick brown goo that can cause serious problems...

 

Cooling system purge of air in the system, I have had that problem with other vehicles I own and yes the "steam" in the system plays havoc
with temp readings and "hot spots"
Thanks for reminding me about different antifreeze
I did ask the mechanic if he placed the cooling system in a vacuum and he did not

 

There's no harm in doing the official bleed procedure, but from my (limited) personal experience, it may not matter much. As I've previously mentioned, these cars will slowly do a self-bleed with normal driving. After any cooling system work, you'll get some gurgling from the heater core, erratic heater output, and may even see the temperature gauge intermittently climb a little bit above normal. But after several drive cycles, and making sure the coolant level is correct each time, everything settles down again.

In my highly over-rated opinion, the factory bleed procedure was probably created because you couldn't return a car to a customer like that. A customer would be upset to pick up their car after service and have things acting erratically as described above. Plus, you couldn't expect a customer to make sure the coolant level was topped off after each of the first few drive cycles.

But me? I'm cheap and lazy, and proud of it. I'm okay putting up with these slight annoyances if it means I don't have to stand on one foot and hold my tongue just right to bleed the cooling system the "correct" way.

Of course, I may be wrong less correct than usual and will quickly hear from the pros about damaged engines caused by improper bleeding...

 

Follow up from last year.
It seams that the cooling system is behaving itself as I have not had any summer or "winter" problems here in So Az

Thanks to everyone for my "education" on S type cooling systems