Ford Repair: radiator boiling over, fan blades, 1991 ford explorer

Question
Ihave a 1991 ford explorer i have replaced the radiator,the fan blades,the thermostat,and had the engine flushed  it does not overheat on the highway only around town when the gauge in the truck reaches midway in the normal operating range the radiator is boiling over not sure is causing this mixture is in normal 50/50 range

Answer
Jeremy,

You should have the temperature sensor checked (this is what turns on your fans when it gets to a certain temperature). Also check the radiator hoses, especially when hot, the hoses could be collapsing from age. The only other thing could be that the cap on your radiator may not be maintaining proper pressure and needs to be replaced. Hope that this helps and good luck. If you need further assistance, please do not hesitate to contact me.

Ken