Black over Brass Overflow Tank or Expansion Tank to capture and retain any overflow from your engine's cooling system.

Made of Brass - will not corrode or crack

Painted black
Measures 2" x 18"
Mounts vertically

Made in the U.S.A.

How does an Overflow Tank work?

When the fluid in the cooling system heats up, it expands, causing the pressure to build up. The pressure cap is the only place where this pressure can escape, so the setting of the spring on the cap determines the maximum pressure in the cooling system. When the pressure reaches stated psi, the pressure pushes the valve open, allowing coolant to escape from the cooling system. This coolant flows through the overflow tube into the bottom of the overflow tank. This arrangement keeps air out of the system. When the radiator cools back down, a vacuum is created in the cooling system that pulls open another spring loaded valve, sucking water back in from the bottom of the overflow tank to replace the water that was expelled.