idk. it hasnt overheated since yesterday. was leaking out where the tube goes in. wonder if the hot water going in was just dripping out while driving and overheated bc no water.

 

This means when the cooling system cooled down it would suck in air instead of coolant.

 

THats ****** great.

Tube goes in where?

Hot water going in where?

Dripping out where?

.

 

Yup, the OP is not very detailed, I had to guesstimate what he is saying...

OP seems to be saying: the tube coming from radiator neck and going into the overflow reservoir...

OP can you confirm this...?

 

The system is closed when you put your cap on.

The radiator cap will overflow out into the overflow if the pressure builds too high in the system.

The overflow is not quite anything except a place to catch all the fluid that may come out.. so it doesnt go onto the ground/into the environment around you

 

The radiator cap also has a vacuum valve, as the coolant cools down it contracts creating vacuum which draws coolant back in from the overflow tank via the cap...

if the overflow pipe leaks (which is what we think the OP said) then air will be drawn in instead of coolant.