Sitting still and getting hot is air circulation prob....Cruising and getting hot is coolat flow issue....

 

Don't take much to plug our little radiators....found out my self today....

 

Have you checked your fan clutch? When I re-did my cooling system, I flushed the rad three times, replaced the thermostat, checked the water pump, did the ZJ fan clutch upgrade (mine was shot) and since my A/C doesn't work (don't use it anyhow) I removed the A/C condenser. Now, my temp never goes over 210 even when slow crawling. Stock radiator and my e-fan does work but never has to kick on cause it just doesn't get that hot anymore. The shroud does make a big difference since our XJ's are designed to run hot (bad design in my opinion).

 

yeah with a used one, but it looks brand new. there are no leaks anywhere, coolant is flowing through the bottle and its nice and green.
I will try to find a infrared thermometer and test things this way.
Another thing i might do is try to get it to 218 and if the e-fan comes on, that means it wasn't overheating the whole time the gauge was fluctuating and the fan was off ... right?

 

Block grill with something to prevent air from being pulled thru radiator should warm right up ....used cooling system parts are a nono unless you've seen them operational on a vechicle with no over heating issues .When temps climb while stopped turn ac on see if temp drops .