A bad valve can cause this sort of sound.
The gurgling sound is caused by pressure in the engine coolant system(antifreeze) slowly releasing into the coolant overflow resevoir. Typically a faulty thermostat causes this sound.
The presence of fluid and/or mucus, giving characteristic signs when listened with a stethoscope e.g. rales.
A gurgling sound in the ear can be caused by fluid moving in the middle ear due to Eustachian tube dysfunction or blockage. It can also be a result of changes in the inner ear pressure, such as during yawning or swallowing. If the gurgling sound persists or is accompanied by pain or hearing loss, it's recommended to see a doctor for further evaluation.
making or characterized by a hollow bubbling sound."a faint gurgling noise"(of a baby) making a contented sound."a gurgling baby who will one day inherit the throne"
Overheating. Have the cooling system checked.
It is not smoke. It is steam. Moisture is making the gurgling sound and moisture coming in contact with a warmer surface (the coil) is evaporating making steam.
A burble is a bubbling, gurgling sound, or a rapid gush of speech.
A cooling system is supposed to be drained not just to rid the gurgling sound. It also helps the plumbers to clean and unclog any accumulated residue.
Airpocket(s) in the cooling system. Did you flush your radiator recently? If you didn't then it might be cracked, and letting air in, or the fluid might be low.
Murmur
A sort of a rush, a whistle, a swissle i suppose ;)