We got this car really cheap from a friend since it leaks coolant (it runs out in about ten minutes of driving). My wife noticed the other day this hose that is not connected to anything (shown below) when she was filling up the reservoir and it made a sucking sound and coolant leaked out of the hose.
For the life of me, I can't find anywhere to attach it to. Is it an air intake? Since coolant is leaking out of it does that mean there's back pressure from the engine?
If that hose is attached to the coolant reservoir for your radiator, the other hose that exits (enters) the coolant reservoir should be connected to your radiator at a point just above the sealing gasket of the cap.
When the system is filled to the proper level, the fluid in the reservoir is likely to be reaching a mark on the side of the tank between "low" and "high."
If a condition results in coolant being forced from the radiator (higher than normal pressure), it will be "stored" in the reservoir. Ostensibly, the fluid will be returned to the radiator when pressure is reduced.
If there is an excess of fluid forced from the radiator, too much to be stored in the reservoir, the hose will direct it to the ground.
Ensure that the end of the hose is pointing to the ground. There is often a hole in the fender wall into which the hose can be pushed to allow for this.
