got a 94 xj with the 4.0 auto, and for some reason the temp gauge has randomly started acting weird. When you start it up, temp reads about 210 then as you drive it settle in about redline hot..but it's not overheating, not losing water, just reading in weird locations. If i unplug the sending unit at the thermostat housing the gauge doesn't move. any ideas?

 

It could be overheating but not boiling.....if possible, check the t-stat housing with a point-n-shoot infrared temp gun to verify temp. Check wires on temp sending unit/gauge.

 

the reason we dont' think it's overheating is that is starts out from cold start at 210

 

U didn't say "from cold" in 1st post, check wires/electrical connections, etc. Factory gauges are known not very accurate, still good to verify accurate temp.

 

get her fixed. replaced the coolant temp sensor on the head. works great now, even reads below 210 for a change. Bugger to replace, but wort it.
Thanks for the help