Very pleasant working with no bonnet
That may become standard procedure.
The rusty lump is the water pump for the heater. Its built in to the side of the heater valve block and is supposed to push coolant through the two heater cores as the engine water pump doesn't have enough flow or pressure to get through the valve block. When the pump fails it just takes a while for the heater to heat up.
Good working valve blocks with good working motors are unobtanium now so I plan to redesign it using parts from the C7 A6 which has separate valves and pump. They're newer, cheaper and smaller. It's just going to need some creative plumbing to stick it in the space where the D2 valve block goes.
The drains are all clear now
