Check to see if radiator fan is coming on. If not it could be a sensor or a relay or the fan itself. You can test fan by unplugging and applying 12v from battery with a couple wires.
December, 20, 2010 AT 9:14 AM
Check that the thermostat is opening, check the fans are working, are you using coolant? If these are all OK get the radiator checked for blocked core tubes, and get a head check done for a head gasket problem, also ensure that the radiator cap is working and holding the correct pressure.