Finally got to that engine heat issue.
Since it was getting really bad with the engine getting hot while idling, I decided to investigate. I took off the cap of my radiator and found that there was a lot of green muddy buildup in there:
I had already bought a new thermostat for the Jeep, because the one that was in there already was staying stuck open:
After taking off the thermostat housing from the front of the engine, I tugged on the old thermostat, which was stuck open, and the whole thing just BROKE. Yeah, I think it was definitely in need of replacing:
It was pretty nasty in there:
I cleaned up the gasket area real well on both the thermostat housing and the engine head before applying a little permatex to the gasket and re-applying. Then I tightened in the new thermostat.
Now one more thing... with the thermostat replaced, and the obvious need to get all that crud out of my engine and radiator, it was time for a full flush and engine cleaning. To help with this, I installed a T connection in the top coolant line to make it all easier:
I then emptied the coolant system and filled it up with a mixture of water and oxalic acid to eat away at the crud. I ran the engine at 1500 rpms for 2 hours straight with this solution, and then drained it and added water and sodium carbonate and ran the engine for 10 minutes to neutralize the acid. Then, I flushed one more time and added all new coolant and water to finalize the process.
The Jeep is now operating at 190 degrees with a very nice idle.