Mark, think we talked about chargecoolers last time I saw you last year? I did mention converting to an electric pump as the way to go...as for the overflow of coolant. I have just the single header on my s4, yours is the twin type? As the outlet from the chargecooler to radiator is next to the bleed hose, which is the one you talk of, they share the same chamber inside the chargecooler unit, under the filler plug. As the coolant flows through the cooler and out, a certain amount will flow down that route to the header tank.i woukdnt worry about that. The main concern is the fact its not cold. As mentioned, change to an electric pump. It cuts out any hassle and is more reliable/ efficient.if you have a radiator issue...youve stilk got. The spare rad? Eventually if you have an air lock in the system, it should bleed out. My money is on changing the pump as we previously talked. Youve got my number, give me a call if you like. Darren