You must use a thermostat. Check the auxiliary water pump mounted to the radiator fan shroud to see if it's functioning.

 

any specific way to test that?

 

Is there power to the connector? If so, does the pump function?

 

+1 on that! The thermostat and related plumbing is totally different on our cars, compared to older vehicles with the more common design. Basically, with the thermostat removed, coolant flow bypasses the radiator, quickly causing overheating. More details here, post #41:

https://www.jaguarforums.com/forum/s...3/#post1693028


Have you checked the actual coolant temperature yet with an infrared thermometer? I'd hate to see you trying to fix a potentially nonexistent overheat issue when the real problem is indication. Also, did you test the new and old thermostats for accuracy in a pot of water?

When does the temperature seem to climb? At idle, while stationary? That's low RPM (low coolant flow) and low airflow through the radiator. Does the indication stay within limits above 30 MPH or so? That's more coolant flow and plenty of airflow through the radiator. These are big clues to properly diagnose the issue.

 

a little out the way, but i tested the original thermostat that came off the car and it opens up in boiling water, i take it out of the boiling water and a couple seconds later after the water is off it and cools it’s closed. i put it in again and opens up. so the old thermostat is good, welp now to the next thing. I haven’t drove the car much BUT i have started it here and there so battery doesn’t give up on me and the belt screams like mad and sounds like a bad pulley, my guesses towards the water pump i’ll take a look into it tomorrow and check around for obvious signs if it is the pump. are water pumps notorious for going out?

 

A good way to get a feel for that sort of question is to use Search, then not only see how many results there are but how many are recent.

Also see if anyone's done a write-up.

My feeling is: very rare.

But things fail sooner or later and you've an old car...

 

Okay i will check the pump in the morning, ive seen some posts of the water pump going out and they do have plastic impellers in them

 

Use a breaker bar to release the belt tensioner. With the belt slack, try shaking the water pump pulley. If you feel any movement, the bearing has failed and the water pump must be replaced. If the water pump pulley checks okay, shake all the other pulleys, too, until you find the bad one.

Has the belt been screaming this whole time? Even if the water pump itself was okay, the belt may have been slipping relative to the crankshaft due to something else causing extra resistance, such as high drag from the alternator. The end result is the water pump (and all other accessories) spinning slower than normal.

 

Okay okay, i know i haven’t replied but i haven’t really drove the car much. i went to mechanic today and it’s a 10 minute drive and when we went the first thing we noticed was the radiator was dead COLD. and i drove back home and it said it’s overheating but the radiator is a bit warm (no where near hot hot) on the left side but stone cold on then right. he told me replace the radiator, what’re y'alls thoughts?

 

Sounds like he's just making an expensive guess. Are you saying the radiator is only warm at the inlet, but still cold at the outlet? That may be normal if coolant flow is very low, such as if the pump had failed or the drive belt is slipping.

Did you ever resolve the squealing belt? Did you ever cough up the $20 for an infrared thermometer so you can avoid spendy guesswork?

 

If the radiator is cold to the touch at both ends, the thermostat is stuck closed thus the overheating condition.

Use an infrared thermometer to find out what the temperature of the upper radiator hose is where it exits the thermostat housing.

 

This is not the way I see it. If the radiator is cold, it just means that circulation through it is low or non-existent.
The situation could be caused by any blockage, including the thermostat for sure, but also any other blockage, including a non working water pump. If SC there is an electric pump as well!
It could also be caused by a lack of coolant generally, or a "vapour" lock, just air around the pump.
I think chances are the system is not bled properly. It could also be a failing water pump, where the impeller has come off or where the impeller is blocked. By pressing the biggest radiator hoses repeatedly, it is possible to drive any trapped air out. I would try that, with an open filler cap, press the biggest hose you can find, repeatedly, and top up as you go. Once the system is full, go for a short drive and return, Let the car cool and check level when cold. Top up as necessary.
The chance of exhaust gas escaping into the coolant is also a contender, which would result in overheating as water is forced out of the radiator or into the cylinder. If repeated bleeding does not cure it, I am afraid you have a headgasket problem.
If the thermostat has been tested, it is unlikely this is the culprit.
Depending on the level of experience of the owner, these engines need a bit of bleeding before the cooling system works.
The later models can show temperature on the display. Press the left stalk repeatedly, from memory 34 times, but I have written somewhere how to do it. My car is standing without battery at the moment, so I can't check for you. I will see if I can find the write-up. I never drive without activating the display!

Found it:
"I think that I have found it!
In the menu press until you reach "Temp in xxxx" The number is the temperature in degrees Centigrade x 10! So 1024 means 102.4 degrees.
I will try and monitor, but i am fairly certain this is it.
If so, then you don't have to rely on the gauge any longer."
It works.
You have to press the stalk while switching on, and hold it until "menu" shows. Then press repeatedly until you see "temp in xxx" From memory about 34 presses! Don't worry, you get used to it!

 

Good point, but here's the kicker. Virtually no troubleshooting has been done yet. We've got a mechanic making a very expensive guess. Still no confirmation of proper coolant flow anywhere. No resolution of the squealing drive belt, so maybe the pump is seized or is being driven very slowly. Heck, do we even know yet if this is an actual overheat or just indication?

So many variables, so few answers. I think the best starting point is to point an infrared thermometer at the thermostat housing. If coolant flow is low or nonexistent, you'll see it. If this new, untested thermostat is bad, you'll see it. If the indication is bad, you'll see it.

In theory, you could change every part in the cooling system and be reasonably assured of a good fix. Or you could quickly isolate the fault with a $20 infrared gun and come out WAY ahead for money and time.

 

Extensive guessing and speculation can become very expensive very quickly on a Jaguar.

The cooling system must be bled using the method described in the Workshop Manual to eliminate all trapped air. In a previous post, there's a recommendation on checking the auxiliary pump fitted to the radiator fan shroud to see if that functions so it can be eliminated as a possible cause. In my personal experience, I will only use a Jaguar thermostat as many of the aftermarket ones I've used have been defective out of the box.

If the OP suspects the water pump is the culprit, it's easy enough to replace if the water outlet containing the thermostat is out of the way.

 

I drove the car to my buddies house, it was running fine on the highway until i pulled into his shop, we are looking at the car and boom 4 minutes into it the water started pushing out the Coolant tank, it was boiling over, don't know if i need a new reservoir or not. But okay, pulled the water pump out, the impellers look fine they are still intacted, ill order an airtex one because the ac delco one only had 5 bolt holes not 6 and so i had to return it. I had the time to go ahead and remove the radiator, should I just get it flushed? I saw a date on there included in the picutre (08 Jan 14) is this 2008 January 14th? or January 8th 2014? I had the chance to remove the DCCV and the Electric water pump on the fan shroud. I'll check the pump flow by wiring it (12 volts) to it and run it thru a tube of water. The thermostat has been changed but i'll check it with a pot of water that is boiling. i took off one of the bleed screws on the intercooler right side the small one and it broke off i need a new one anyone has a part number?

 

I think it increasingly looks as if you have a problem with a head gasket(s). You most likely have exhaust gases escaping into the cooling system. Because the exhaust pressure is much higher than the cooling cap pressure, it forces water out and eventually overheats when there is too little, or, the water is sucked into the cylinders ans the result is the same.
The radiator date is far later than the car, so someone must have had problems in that area before.
I would see if you can do a test of the cooling system, either a pressure test or a "sniff" test of the coolant to check for hydrocarbons, or both!
Sit down, breathe hard and face facts.
You can replace the gaskets yourself, if you are that way inclined, but it is a case of slowly slowly, catching monkey.! And get an experienced friend to assist!

 

Okay! So, so far i have gathered that i have a possibility of a cylinder head gasket failure. now i am so far into the removal of the radiator that i might as well go to a shop and get it checked out? and get it cleaned? and if everything checks out reinstall everything, i might throw in a new thermostat and once that’s fine, completely bleed the system and go check it out. if everything is fine then a-okay, if not then do a combustion gas test from the reservoir and if that’s my problem then what all do i need to replace? gasket set and what else? also could the aux and intercooler water pump cause overheating? Thank you to everyone for the help

 

okay, i bought a new water pump today. and wow the difference. i haven’t put it on yet but the play in the shaft in and out and side to side is really bad. and so is spinning it. it is very loose and spins freely. while the new one is very tight and firm to spin, no movement in and out or side to side. could that be a possibility?

 

The water pump can only be a culprit if it is not transporting water. Looseness and play makes no difference! It is only if the blades have been prevented from transporting water that it will be important. That can only be if either the rotor has come off the shaft, or is lose on the shaft or if the blades have been damaged.
All of that would require a removal of the pump to establish. It is not clear to me if you have the old pump off or not?

 

Yes, the water pump is completely off the car