You said it opened when you boiled it?? If it opens and closes the thermostat itself is working. You said 190-195 was when it opened in the pot, so it “could” be a mislabled 195F in a 180F box (it happens). A bad thermostat is a unit that fails open or closed, but no longer moves.

I have used a lot of Britpart black 180F stats (always visually verify the temp rating on the copper part of the stat or outer ring. I have come across 1-2 in my day that were OEM temp stats in 180F boxes & I quickly got them swapped out with the retailer.

I watched a video of a guy not to long ago flushing his D2, and he was going by how the water looked saying it’s coming out nice and clear now. However he DID NOT take notice of the small flow rate he had coming out. He finished his video & quickly posted after flushing it the D2 overheated. He gave up, had a shop tear into it, they replaced his OEM radiator & it was basically completely clogged up with orange goo that no flushing was ever going to remove.

Point is if I don’t know the mechanical history of a D2 and I’m going thru it a 50-75 radiator is #1, followed by ditching the $$$ 03-04 one piece fan blade/clutch, changing out hoses, fully flushing the heater core, 180F thermostat, TBH delete, and using green coolant. I live in TX & all my D2’s run 172-206F depending on the season/temps.

Also with all these temps you’ve experienced has the Aux E-Fan ever ran?? You’ll have all sorts of crazy temp readings due to an air pocket in the intake where the temp sensors are, but if it goes over 207-210F the E-Fan kicks in to help cool.

I use my Scangauge II for onboard temps & an accurate IR Temp gun for outer temps.

 

 

 

Temps are very similar to mine. I'd be OK with those. I idle 201-206 in 75F weather. As long as I don't go over 208 I'm pretty happy, especially with a top hatted block.

Might also be worth monitoring oil temp with an aftermarket gauge.

 

Still sounds like air. Its NOT the water pump.

 

 

 

Which is the normal temp range for a 195F thermostat..

 

I just made a video today about my overheating issue.

 

Countless issues with that video, no offense.

The goal, when you think you have an issue, is to arrive at an solution that is the real answer.

Swapping stats, testing radiators based on water flow, on a system with serious design flaws, WITHOUT addressing those flaws, is just throwing parts at truck and wasting time.

Why even bother if you dont know if you've even bled it?

Rent a camera from an auto parts store and LOOK in the rad to see if its clogged, cap it off and flush it PROPERLY if you think it's the issue.

I've seen brand new rads with cool areas, it happens because of the flow pattern inside. If a rad is open, it can have a high flow area...through the middle or bottom...maybe the top. Another thing, a rad usually can handle losing multiple rows. You can remove 3-5 rows and still have enough cooling to keep the temps in specs. Problem is, rovers cooling system has flaws.