When your car is overheating you should pull over as soon as it's safe and turn off your engine. You should never open your radiator cap when your engine is hot, the coolant is under pressure and it is very hot and cause burns. You should also never pour cold water into a hot radiator the water could instantly boil and then shoot out of the radiator causing burns. The best thing to do is to wait until your engine has cooled off this could take 20 minutes to up to an hour.
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