The importance of the radiator cap and coolant tank cap within a cooling system often goes unrecognised, yet they are fundamental components. These caps do a lot more than just fulfil the function of closing the filling hole of the radiator or the expansion tank gastight. They also ensure that the prescribed pressure on the system is maintained at all times during operation by allowing air to escape in case of overpressure. Therefore, they are one of the smallest but most important parts in keeping your customer car’s cooling system operating efficiently.