why my ford explorer 2002 running hot

Is cooling fan turning on when the engine reaches operating temperature? If so then the problem could the the thermostat or the cooling system needs to be flushed with pressure applied to the lines.

HOW HIGH DOES THE TEMP GAUGE GO UP? if it doesn't get up to the max the engine isn't in grave danger-yet. A partially plugged catalytic convertor, or a slipping automatic trans can EASILY cause the engine to run hotter than usual. As can an engine that is running too LEAN. And a bad temp. SENSOR can indicate too hot when its really not. Is there ANY exhaust leakage close to the engine? (ex. manafold/rusted pipe/damaged gasket) A automatic trans LOW on fluid will run hot enough to feed plenty of extra heat into the radiator-enough that it can't keep the temp down. Let the engine run with the trans in park for say 10-15 minutes and see if ithe gauge still goes up as high. IF you have an ELECTRIC engine cooling fan and it NEVER comes on, it could just be the water temperature sensor, or the fuse associated with it, or a problem in a connector to it, or a bad wire. IF you have a MANUAL engine cooling fan and it freewheels when the engine is HOT, you need a fan CLUTCH. To double check THAT, warm up the engine fully (and shut it off) and try to turn the fan by hand. A good fan clutch will let the fan turn easily when the engine is CXOLD and be very hard to turn when the engine is HOT. To absolutely rule out the thermostat BEING STUCK SHUT: When the engine is COLD, pull the thermostat AND PUT IT IN A PAN OF WATER AND GRADUALLY HEAT UP THE WATER (with a thermometer also in the water). It should be fully open by thetemperature stamped on the thermostat. If it ISN'T fully open then replace it. (test the new one too-before installing it) More invasive: How do you KNOW that the water pump is good? In some cases a water pump's IMPELLER (looks like a fan blade) will erode enough to decrease the flow below the point needed to cool the engine. Only way to check this is to pull the water pump and LOOK. If YOU haven't replaced the water pump in a couple years its worth checking-but save that for last.