first you will have to make sure your thermostat is opening and you have plenty coolant in your system,feel top radiator hose if it is hot,good chance it is opening,look for circulation in your expansion tank to check water pump is operating ok,look inside tank and if you see bubbles in coolant your head gasket may be at fault and also if your cooling system has excess pressure in it,same thing,good luck
cdc
March 2011