Cadillac Repair: 1993 cadillac sedan de ville, core failure, head gaskets

Question
QUESTION: heater core failure. I had the core changed 5 times. any suggestions please.

ANSWER: What is happening to the heater cores ?. Do they spring a leak or are they plugged up internally ?.

---------- FOLLOW-UP ----------

QUESTION: they spring leaks

Answer
The fault is either a faulty radiator cap or the WRONG pressure cap for your specific vehicle.

The most likely cause is a very very common occurance of faulty head gaskets whereas combustion chamber pressure is being distributed into your cooling system due to the faulty head gaskets.