Re: What does this go to?
It is a coolant recovery tank. It mounts anywhere that is close to the level of the top of the radiator and is connected to the overflow tube from the filler neck. Coolant is put into the tank so that is s about half way between the cold and hot lines. In operation, when the coolant in the cooling system gets very hot (like when the car is shut down after a hard drive, there is no longer air throughthe radiator to keep the coolant at the normal temperature and it rises, causing he coolant to expand. When the expansion reaches the point that the pressure in the system rises above the pressure of the filler cap, the inner seal of the cap lifts and the excess collant is expelled (onto the ground in cars without the recovery system or an expansion tank). This excess coolant is now routed into the recovery tank. When the cooling system cools off, the coolant contracts and causes a vacuum to form in the system. This vacuum will now pull the coolant in the recovery tank back into the radiator through the check valve (the little spring loaded disk in the center of the filler cap). This is a very simple add on system that works quite well, keeps the radiator constantly full to the very top and is not plagued by the problems of a pressurized expansion tank (cracks forming from the constant expansion and contraction).
Cheers,