What is the reason why the car is not hot and the kettle is running backwards?

The car is not hot, but there are two situations in which the water tank returns: 1, and the water tank returns when the big foot steps on the accelerator: this situation is mainly caused by a large gap or crack in the wet cylinder liner or cylinder head. When the engine is working, the pressure of compressed air or gas in the cylinder is greater than the pressure of coolant in the cooling channel, and these combustible gases will enter the engine channel from the gap, so the kettle will pour water. 2. When the engine is working, there is no air in the coolant: regardless of the water temperature, the coolant will be sprayed out from the water inlet when the water inlet of the expansion tank of the fuel filler is not sprayed out.