The A4 is a thermostat BYPASS engine .... meaning if the thermostat is CLOSED (bypassing the flow 'around' the engine) ... the entire flow of water is THROUGH the block. When the thermostat is OPEN, water BYPASSES the engine block.
You have that backwards NO water can flow through the block were in enters through the tee on the water jacket plate When the thermostat is closed other than a small amount through the air bleed hole in the thermostat
It ALLWAYS goes through the bypass to cool the exaust manifold
Yup you're right. .... must have been momentary 'dain bramage'. I corrected the previous post.