Cracked head or liner?

[hhow55]

Well, The first mistake was isolating the egr cooler, preventing the necessary flow from occurring. It's good that you checked to see if the engine air compressor is causing the cooling system to pressure up. The next step I suggest, is too to buy yourself a coolant pressure tester, pressure up the cooling system, drop the oil pan, and see if you have coolant running down the inside of any of your liners. If you do, this is sure sign of a bad head gasket, or cracked head. Mine turned out to be a bad head gasket, when it did the very same thing yours is doing.