coolant overflow

Posted by sunrise On 2009/4/7 20:51:34

Hello i have a 1951 Packard motor that when runs for a short time,the coolant slowly comes up over the rad.fill opening if i put the cap on it will over heat and boil out,when i turn the motor off the coolant poors out the top i find no water in the oil pan so i don't think it is a leak in the eng block
what would cause this to happen .Thanks in advance Frank