The truck is overheating. The radiator is not leaking. Help I don't know what to do.

 

Did you check the top radiator hose coming from the thermostat. Make sure the coolant is flowing when it reaches operating temp. Maybe your thermostat is stuck closed.

 

Check front radiator fins for debris blockage, collapsed fins restricting air flow. Rotate cooling fan by hand(engine off!!) it should rotate freely with some drag, if it free spins or makes noise the fan clutch is worn out. Check upper radiator hose when engine temp is around its normal operating range, if hose is still cold when the engine temp has passed operating temperature, thermostats are stuck closed. Or you may have a water pump impeller issue or simply a coolant temp sensor bad. Start with the basic checks and go from there.