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Q: Car is overheating and boiling water out. 2003 Hyundai Elantra

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I have replaced thermostat and radiator also installed new valve cover gasket when I installed new radiator cap extreme pressure built and I shut the car off and tried to release cap and it blew off with a loud pop from the pressure so I tried to troubleshoot and found the overflow hose was clogged so I flushed it out Car is losing water via overflow steaming out of the open valve in the overflow cap and old radiator cap. There is a smell of gas that comes out of the radiator and it gets hot way to quickly and the top hose stays hot while the bottom hose is cold but you can see when the thermostat opens after a bit and the water level drops the only thing I can think of would be the head gasket blown or cracked head or possible some kind of blockage keeping the water from flowing through the engine to the radiator at the proper rate can you please give me any ideas or methods of troubleshooting.

My car has 200000 miles.
My car has a manual transmission.

Hello - you may very well be correct. Given your symptoms, it sounds like you have a blown headgasket. This can be confirmed by checking for low compression between adjacent cylinders, white steam or smoke from the exhaust (smells sweet), and chemically checking for combustion gases in the engine coolant - the "gas" smell you notice in the coolant already. I would recommend an engine inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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