So if you want and try to drop the temp of your coolant in your Disco here are the things to try.

Prior to flushing the system, take an infer red thermometer (harbor frieght $35) and when your Discovery is warm up check the temp of your radiator. To do this split the radiator up like a tick tac toe board and take readings in different sections. It should be hotter where the water enters the radiator and cooler where the coolant pumps back to the block.

If you find a section that really different note it on paper.

Then flush your system completely, refill and check the temp again. Basically your looking for blocks in the radiator.


2nd water is circulated by the water pump. All water pumps fail, seals let loose, barrings go, pump fins get corroded. So if you still don't like it a pump is a good place to look.

A month ago my son bought a SAAB, the previous owner complaint it was always over heating. I drove it and the temp was hitting about 240. So I turned on the heat and it dropped to 225. So I took it home and infer reded the radiator and low and behold. The radiator was cold. I guess I should of touched it but burning my fingers is not on my list. So this person had a new water pump and new radiator put in and the mechanic didn't fix the problem. We bought the 2001 SAAB turbo that was over heating for 800 buck. I then put in a 50 dollar thermostat and the car works perfect.
LOL best deal of my life

 

the below posted is wrong
the 180 thermostat controls the flow of coolant threw the radiator,
there is no heater control valve on a DII so you heater is always on.

201 is well with in the OK range for your Discovery. Secondly, what a 180 degree thermostat does is open the valve to your heater when the coolant temp hits 180 degrees. If your heater is on, your temp will not drop. Now I may be dumb here but it is summer and the odds of your heater on are small.

Thus in a nut shell a 180 thermostat does not and will not affect the running temp of your Discovery.

 

So let me get this straight if you have a soft thermostat that fully opens at 180 Degrees it will run cooler than a normal stat that opens at 190 degrees.

So to explain what happens at 180 degrees the thermostat opens fully. The key word is fully so it has maximum flow through your system at 180 degrees.

Now if a normal stat allows maximum flow between 190 and 195 degrees, the system is running as much coolant as it can once the temp hits 190 degrees.

Now lets take a car at 201 degrees, it doesn't matter whether the vehicles thermostat open at 180 or 190 it has maximum flow of coolant. The 180 stat is allowing more flow of coolant, it's not like turning it up to 11 from 10, it is at its maximum flow.

Thus for a car running at 201 degrees a soft stat will not increase coolant flow, thus it will not reduce the temp of your car. That is not what a thermostat does on a car. A thermostat soul purpose in life is to warm a vehicle up faster so their is less wear on your engine. It does that by shutting of flow to your radiator and to your heater core. Unreal your last post

 

You understand that a thermostat open and closes constantly, modulating your cooling temperature it does not just open one time and stay open all day.

 

again once your car reaches approximatly 190 degrees your thermostat opens and stays open, provided your coolant temp does not drop below 190 degrees. Its sole purpuse is to get your cars temp up to operational twmp as quick as possible, its purpose is not to regulate the temp of your car.

sorry you are confused by that is what it does. here is a one paragraph article that explains it.

Any liquid-cooled car engine has a small device called the thermostat that sits between the engine and the radiator. The thermostat in most cars is about 2 inches (5 cm) in diameter. Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens. By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.

 

its purpose is not to regulate the temp of your car.

good bye

 

But if my thermostat isn't opening till 203 then my truck will run warmer than one that opens at 190. My motorad is defective so my truck is running warmer than the stock thermostat.

 

that is correct, just like a car without a thermostat will overheat long before a car with one.
the simply reason is there is nothing holding the coolant in the radiator long enough for it to cool down, it will just rat race around getting hotter and hotter with each pass.

 

are you serious?

please read a book or watch a video on how a coolant system works

Yes a thermostat that opens at 202 is holding the coolant a little to long, but 202 is again with in spec. the thermostat works with wax. when the coolant hits a certain temp the wax melts and is now liquid and the thermostat stays open till the wax solidifies. with a soft thermostat the wax melts at a lower temp opening the stat a a lower temp.

 

...this is getting good...