I had just bought the car at an auction and made it 5 miles out before the temperature gauge starting going towards the top. Pulled over and checked the reservoir which was empty. Let it cool 10 minutes and drove a few miles to a parts store and added a gallon of coolant and a half gallon of water. That got me the 30 miles home where it took another gallon of water. I put a pressure tester on it and it started leaking water under the car, I couldn't tell from where at the time but now see there is a hose from the pump just for that. When I turned the engine on it it also leaked from that vent hole on the side. Was not making any noise.