EGR cooler or head gasket?

[ecrankshaft]

I have a '98 Jetta TDI which is blowing coolant out of the overflow tank when warmed up. It runs perfectly, starts right up when cold and has 122k miles on it. I replaced the radiator which I believe was partly plugged and the thermostat just to be safe in hopes that this would remedy the problem but it still persists. I was planning to pull the cylinder head off assuming the head gasket was blown and to inspect for a cracked cylinder head but was told the EGR cooler can mimic the symptoms of a blown headgasket. Anybody have this problem?

I am going to try bypassing the cooler to test again and plan to do a combustion gas test on the cooling system but I'm holding onto a glimmer of hope that it is the EGR cooler instead of the cylinder head. Thanks!