In applications where our 200 Series pumps are not available or suitable, we recommend our WE100 expansion tank. A properly plumbed expansion tank can cure many cooling problems associated with trapped air. The tanks work great when used in conjunction with a remote pump. The pump has a full size radiator cap opening on the top, a -8 AN female fitting on the bottom and 2 1/4 NPT fittings on the sides. The tanks come in a variety of colors and finishes. Expansion Tank Info: An expansion tank is sometimes referred to as a surge tank, header tank or air separator. The tank has two main functions. It is used as a fill point when the top of your radiator is lower than the engine’s water outlet. The bottom of the tank is plumbed to the low pressure (suction) side of the cooling system (after the radiator core and before the pump impeller). The smaller fitting on the upper portion of the tank is plumbed to the high points on the engine and radiator to remove trapped air and aerated water. This reservoir located high and out of the main flow of water allows air to be purged from the system, making the entire cooling system more efficient.