i have a 1999 civic ex 2-door automatic.
my radiator broke yesterday (started leaking badly)
i bought a radiator today and did the install.
when i turned on the car i noticed that the radiator fan didnt turn on, i did the usual tests . fixed itself after switching relays.
now the fan is working but the temp still keeps going up
i noticed that the top hose for the radiator is very hot. the bottom hose that hooks up to the head(where the thermostat is located)(its the longer hose)is not as hot as the top hose

 

it turned out to be air in the system. i still find that the fan(cooling fan) turns on for too short of a time and its not on too often

 

make sure the thermostat is working correctly. make sure all the air is bled through the system also.