Salam. I am using vitz 2013 model. Yesterday on my way to lahore on motorway, by somemistake in closing the cap while checking for water/coolant levels before travel, the radiator cap blew off. When the sign for Heat indication came up at once I parked my car and while lifting the bonnet i came to know that the cap was missing. I called 130 and made them aware of my situation that i need some coolant and a cap. They asked me wether i had water bottles with me to which I replied , Yes. Then they told me to fill radiator up with water at full level come 10km straight where they were positioned. I followed their command and after waiting for 20 mins to cool down cars radiator i filled it with water and then went straight at 60kmph speed (they told me to come at 100) and no indication was present till then. Upon reaching i got the cap and coolant. Still waited for 20 mins for cooling down the inlet pipes and then poured in water and coolant and placed the previously missing radiator cap. Then after reaching lahore the car behaved as usual. Before leaving for Faisalabad i again checked levels and around 100ml water was again added in it. Then today morning i again checked water levels and around 500ml of flud was still added in the radiator. But there is no visible leakage of water. And the cars performance is still as usual with Ac and Speed. So what could be the problem? Has the gasket been damaged or blown?
Please help as I have never encountered such a problem before.