Have recently removed cylinder head on 2005 BHW Passat due to unseen coolant loss and white smoke/ rough idle. Cylinder head diagnostics were fine (no warpage/ pressure checked ok). Cam wear was minimal. Replaced head with new gasket, cam bearings, bolts, etc. Engine cranked fine, idled fine at initial start up but when coolant was eventually topped off (by removing heater core return line and allowing air to bleed out of system) engine instantly begin idling rough, blowing white smoke and now a coolant leak is present on passenger side of engine. I can not visualize source of leak due to tight space in engine compartment. My question is do I assume block is cracked and if so what would be most economical course of action? Any opinions would be greatly appreciated.