Word forms: (regular plural) header tanks
noun (Automotive engineering: Vehicle components, Bodywork, controls, and accessories) A header tank is a container of liquid positioned at a higher level than a main tank, so that the level of pressure can be maintained. ⇒ The coolant in the radiator header tank should have a mix of water and antifreeze. ⇒ Any loss of coolant will show up first at the header tank, and level sensors are available to detect this. ⇒ A well maintained car should show no evidence of water or antifreeze leaks from the header tank or radiator.
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