Overheating 6.0

[Cheyenne man 1987]

Hi guys, I'm brand new and I need some help I have a 2003 long bed 6.0 . I just replaced the fan clutch because my temp went up to 240. Today i was driving and temp went from a steady 210 to 260. Would that be a thermostat or leaking water pump? 

[CamGTP]

Well, is it actually dripping coolant on the ground?

 

That would let you know if something was leaking.

 

Past that you can do more diagnostic to see what you may need to replace. A hand held temp gun could let you see the temps on the hoses and radiator itself to see if it's really getting that hot. If it is, then you may have a faulty thermostat or lack of coolant flow.

[davester]

If it happens very quickly, it's possible the water pump has failed internally (so the impeller isn't being driven by the shaft anymore).  It's pretty rare, but not impossible.