I just spend hakf day reading every piece of related information but couldn't find an answer.
New pump, new rad, new thermostat, new temperature sensor to no avail, it still overheating

Even after removing thermostat every time it idles for 5 minutes, temperature is in red zone.
It's in the middle for as long I'm driving

Fan is working even after shutdown for 5 minutes and no errors to grasp what is going on.

Any ideas where to start looking for solution/

 

The plastic housing for the thermostat, was not mentioned, in your list of components,replaced.
Was it replaced, & if not, why not???

 

Mine is not plastic

 

A very good reason;
Is it an aftermarket, factory, or XJR only part, & will it fit stock XJ8's???

 

Two things, 1st, is the thermostat in correctly? The vent ball should be at the top. 2nd, did you bleed all the air out of the system? I mention these 2 thing from experience. The attached file has the correct way to install the thermostat. You may also want to check the 2 Aux pumps.

 

As I've mentioned

There is no thermostat now.

As soon car on its way, in less than 100 meters needle move to the middle. Heater and AC are working.
You will know that heater is working as soon you stop and needle is in red, blower pushes hot air and
after car moves, it goes back to AC cool.

 

All I can tell is that removing the thermostat is a bad Idea. You should replace and properly install a good thermostat, then properly bleed your system.

 

The idea of being able to remove the thermostat in the hot summer weather.
Worked fifty years ago, but no heat when it got cold it got reinstalled.
You used water straight from the tap, no need for antifreeze in the summer.
You could overheat, blow a hose, or break a belt, and loose it.
But the cooling, fuel systems, & motors were all much simpler then.
Your thermostat is no longer just an option for your heater to work

 

Thermostat is out for now to test if it causing problems. After all here in Canada
winter can start tomorrow. But thanks for advice guys.

We're trying to solve this for more than 1 month now and after replacing virtually
everything including all hoses, we're not an inch closer to solve this mess.

As I said there is nothing in fault codes to grab the string and without starting point,
I afraid my guesses are as good as yours and at least there is someone who have
experienced the same problem and successfully fix it, would be capable to provide
solution and hopefully could give helping hand.

 

As previous Posters have mentioned, your Jaguar will not run correctly without its Thermostat. The Stat is a sort of 'two way' valve, allowing coolant to circulate within the radiator only to cool it quickly, then switching to around the jacket to cool your engine.. ...You will overheat without it!
I write from personal experience?

 

Look at your oil dipstick for a milky substance, (coolant )your head gasket could be blown.
I sure hope your engine is OK, overheating it can often cook the motors head gasket.

 

It doesn't work correctly regardless if its in or out.
Having unrestricted flow at least removing one of possible reasons not to mention that
the main purpose of thermostat is to regulate warming up time in the winter.

Oil is OK and engine is working like a Swish clock

Again, overheating is happening only when car is in parking mode.I can drive all day
and as long I don't stop for longer than 5 minutes, I have no problems.

 

Have you checked the radiator to see if it is clogged? How about the heater core?

Overheating is a result of either not enough coolant flow, low coolant, or not enough air flow to remove the heat. You just have to work through each of the components to see where the issue is.

 

As I said, new rad, new hoses etc. even new blower, flashed system no loss of coolant

 

The engine will should not overheat without the thermostat. Running engine without thermostat at least eliminates it as the fault.

Something else is going on here obviously.

 

Guys, guys, I'm glad you're having good time chit-chatting about what may or may not but...
can we just go back to subject of what is wrong and how to find it and eventually to fix it?


Please let go back to topic, please

 

Try using an infra red thermometer to look at temps at various locations. Might give a clue.

 

Sounds like a flow or blockage problem possibly. Was the thermostat housing broken up when you removed it from the car? Maybe the housing had broken down internally and some of the plastic is somewhere in the coolant system and hence blocking/slowing the flow.

 

As I've said before.
My housing is not plastic, it's cast aluminum and factory original.

 

It sounds like you have tried a bunch of stuff. My only other thought is have you validated the actual voltage coming from the temp sensor? You replaced the sensor, but have you checked the voltage reading? If all of what you are saying is true; flow is good, a bunch of stuff has been replaced, no bad head gaskets, then honestly the only other thought is your sensor is bad or the ECU is reading the sensor incorrectly.

Have you validated the temps coming in and out of the radiator? I am not sure off hand what those should be, but it can certainly help show if the overheat is real or not. You can also check various other hoses to see what those temps are.