When driving at freeway speeds every so often the temp will raise (to 260) very quickly, then drop very quickly back to normal, and not have another issue. Scares the hell out of me everytime.

I can drive it for hours in 4x4 at low speeds going over rough roads and never have an issue.

Also, when it does this it is joined by an annoying ticking sound that seems to be coming from the dash. I dont know if they two are connected, but they are always at the same time.

 

Welcome, Aaron!

I suggest the first thing you do is to test for exhaust gasses in the coolant. A blown head gasket will suddenly spike like that.

It could also be a thermostat, but not likely as it's intermittent, but it can't be completely ruled out.

A bad fan clutch shouldn't bother you at freeway speeds. Same for the electric fan.

As for the ticking sound.... no clue.

One last possibility - it could just be a bad temp sender. Follow the wiring and make sure it's not shorting somewhere.

 

It started doing it a week ago. Last Thursday I changed the coolant ,and let it idle for a long time with the cap off, no bubbling come out of the radiator.

Both the fans come on as they should.


The ticking has got me baffled.

 

So did it start after the coolant change or did you decide to change the coolant because of what's happening?

 

It started doing this, so I decided I'd better do some maintenance. I have only had the jeep for a couple months and the coolant was looking nasty so I had been meaning to change it.

 

get yourself an obd2 reader see if the computer sees what your gauge is showing, since they both come from the same sender. if you jump from 210 to 260 in under 10 sec it might be a bad sender...i dont think you could heat up the water that fast, unless it was getting blasted by 600 degree combustion gasses but that would fill your overflow tank to full overflow. the lower the resistance of the sender...the hotter the indicated temp. if you have time during the incidents...turn on heat to full hot- full fan that can draw away excess hear very quickly . its not impossible but thermostats dont usually snap closed intermittently once open...they may not open, but they dont "snap"closed