it is difficult to determine your problem,was it overheating like this before you changed the radiator?It may have an air lock,check the small hose to to expansion tank isn`t blocked,check you have good circulation of water when you give it a rev to check water pump is ok,is the thermostat opening ok?It may be worth removing and dip it in boiling water to check it is opening ok,if the system is pressurising a lot then you may have head gasket problems,just some things to check,good luck.
cdc, April 2013
