A connector between the engine coolant pipe on the side of the head and the ventilation hose in a car serves an important role in the automotive cooling system. The expansion tank, also known as the coolant reservoir, collects excess coolant that expands as the engine heats up. This coolant needs to be released safely, and that's where the ventilation hose comes into play.

The connector between the coolant pipe and the ventilation hose ensures a secure and effective connection between these two components. It allows the expanded coolant to flow from the expansion tank through the ventilation hose, which directs it to a designated location outside the engine compartment. This prevents any potential damage or pressure buildup within the cooling system and ensures optimal performance and efficiency of the car's engine.