Alright, what am I missing?.?.? You hooked up the cooling water fitting to the stock siphon bilge with a T and are dumping it where? Overboard or piped back thru the bulkhead to cool the engine? Not sure a T like that will create enough, if any, suction to function the way you think. IMO, you are going to fill your hull with water.
That brass fitting should be connected to the tube in the bulkhead that feeds cooling water to the engine. Nothing else. If you have one on each side, then it is set up for dual cooling. If you only run one, just cap the other off with a brass plug.
The stock siphon hose from the bulkhead should connect up to a tube either in the reduction nozzle, and if I'm not mistaken, on the steering nozzle of some of the older SJ's.