If the tank bubbles all the time the engine is running and is black dirty inside the head gasket has failed or a similar failure like a cracked cylinder head.
If it only bubbling after the engine is overheated, the system needs to be checked for other failures.
thermostat or blown head gasket....
Might mean you have internal engine damage like a blown head gasket. You need to get this professionally checked.
The overflow tank is either cracked or its overheating and leaking from the cap
A gas tank can indeed overflow if it is not full. A gas tank can overflow if the pressure inside of it is too high.
I was having the same problem with my 99 explorer. What I discovered was that the overflow tank for the radiator was empty and was causing a false reading by the temp gauge.
Do not take a radiator cap off. Fill from the overflow tank or you will add air to the cooling system and it will have to be bled off or your engine will overheat.
A bubbling noise in a well pressure tank is a sign of a hole in the tank. It means that air is getting into the tank and causing air to bubble through the water.
You are most likely overheating.
It is not common to hear a bubbling noise coming from you gas tank. It may be that your gas tank is too hot. You need to stop your vehicle and let a professional look at it.
Engine overheating will cause the anti-freeze to surge into the overflow tank. A blown head gasket will also cause the anti-freeze to surge into the overflow tank.
Rust from your cooling system is flowing back into the overflow tank when the motor warms up.
is the line that serves as overflow tanks of oil to a tank specific to prevent the oil overflows into the sea.