No Thermostat in S-Type 4.2?
 

For a number of reasons that will distract from the very focused question I will ask here if I describe why, I must run my engine without the cooling system thermostat, if it's possible to do it, for a month of driving. Is anyone knowledgeable about whether the engine can be run for a month of normal city/highway everyday (hundred miles per day, driving in 70 degree Fahrenheit weather), and circulate coolant and not get damaged WITH THE THERMOSTAT REMOVED?

No dont do it becaue the thermostat actually forms a seal in the crossover pipe between the heads. When part of the plastic housing breaks where that seal is the engine will overheat because the coolant doesnt flow correctly. Removing the thermostat will cause the same problem

As Brutal has said, don't do it. The arrangement for the S-Type thermostat is VERY different than most older cars. Long-winded details in post #41 here:

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


To summarize Proust:

On most older cars, the thermostat was a simple on/off device in a basic loop. Remove that type of thermostat and you'd typically have maximum cooling all the time. (Not entirely true, but close enough for the purpose of discussion.)

The S-Type thermostat is more of an either/or device for a passage that bypasses the radiator. Remove the thermostat and nearly all coolant will bypass the radiator, resulting in virtually no cooling. Not good...

I am unable to obtain a new thermostat housing in my geographic area so I need to somehow make things work without a thermostat. I know it's not recommended, but is there theoritcally a way to seal the interior of the thermostat housing (which currently has no thermostat in it but the housing is fine) so as to force the coolant to flow through the radiator as if the the thermostat is in place? I do have access to JB weld and high temp JB weld.

We may need the expertise of one Stanislaus Kowalski for this one. He is the world's tallest man, at eleven feet high! His family hails from the fertile farming region in the eastern part of Poland. If anybody wants to reach out to him, make sure you get Stanislaus and not his little brother Oskar, who is only ten feet tall and not nearly as knowledgeable. This distinction is important, because I don't think you'd want to touch this with a ten foot Pole.

:icon_doh:

Just destroy your engine - that's it!

Read Brutal's words.

Take the car off the road and do the job properly.

I would never doubt Brutal's expert experienced opinion.
What happened to my car was that I started noticing the engine would take forever to warm up in our (mild) winters. And during our hot summers it would also take longer than usual to get to half.
Also during some of the winter nights on the freeway I would notice the temp gauge would now start to sit at a quarter and not in its regular half way position.
I decided to change the thermostat and that fixed the problem, must have stuck open.
Would a stuck open thermostat be the same as having no thermostat?