Overflow Boling

May need to have the cooling system purged from some air pockets. Also make sure the fans are working for the radiator.

I would agree with tennisshoes. You could have a bad head gasket. I would have the coolant tested for combustion gasses.

change your rad. cap. as soon as you shut off your eng. the temp. rises and a bad cap will let it blow off into the overflow tank a head gasket dont do that. and your cap is designed to suck coolant back into the rad. as it cools. also check at the thermastat housing for a bleeder screw because some cars and trucks need to have the air bled from the system when it is filled plus some have two bleeder screws one at water pump and one at the thermastat housing.

Thanks everyone blessings