combustion in the coolant?

[tregrad]

I have gone through 2, TWO! cold case radiators in my Blazer. I have to give props to coldcase though, they sent one to replace the first one I purchase free of charge last october and that one started leaking today. I walked out to the driveway and it was leaking, hadnt even started it yet.
needless to say i am a bit pissed, called coldcase and they said take a pic of the serial number and the leak and they will send out another!! many props to them and their lifetime warranty.
Now, the dude on the other end of the line told me that there could be "combustion" in the coolant? and that could be causing the pressure that is blowing the radiators apart. I personally, in all my years of being a home garage gearhead have never heard of that until today. He said that there wouldnt be the usual signs of water on the plugs or coming out the tailpipe but could be causing the pressure, said he had a 454 that was doing this. Said he changed the head gaskets and the problem went away.
Can a head gasket be bad as to let combustion into the radiator and not into the cylinder ?