Most likely it is coolant getting to hot and boiling over, car is most likely overheating. Check for fluid under car, and temperature gauge.
it could be your valves or your engine
Most common culprit is a slipping belt.
If it is coming from the radiator or the hoses this would mean your antifreeze is boiling in the lines. I would recommend first changing the thermostat and bleeding the air from the rad lines.
It depends on the nature of the noise.
Mine is making a similar noise. Steam is passing through the coolant overflow tube as soon as the motor is shut off. The tube is connected to a nipple just under the radiator cap and the tube travels to the bottom of the coolant reservoir. The coolant in the reservoir then bubbles
If the whistling noise is coming from under the hood its your belt, that's what's wrong with my Sequoia. If its not coming from under the hood its probably a crack in the seem of your window.
There is a baby under the hood.
What causes ticking, check engine light, and the check gauges sensor to come on in a 1999 Dodge Durango 5.2L SUV?
Something is wrong. Have a trusted mechanic check it out before you get stuck.
Serious engine knock or valve train noise. Have this looked into by a pro.
busted radiator? No water filling the cooling system
The most common cause behind a high pitched noise under the hood is the drive belt. if it is worn out or loose, the wheels will slip, creating the noise. I would check to make sure the tensioner isn't bad. If it is, this could be causing the looseness. If the tensioner is fine, then just replace the belt.