Characteristics and functions of the expansion tank for Petrol Car engines

When the thermal load of the Petrol Car engine reaches a certain level, the internal pressure of the cooling system exceeds the opening pressure of the steam valve of the water tank cover, the steam valve opens, and the steam-water mixture in the radiator flows into the expansion tank through the steam condensation pipe connected to the radiator overflow pipe.

There is a 02. vent hole on both the expansion water tank and the water retaining ring (seal gasket), so that the pressure in the space above the liquid level in the expansion water tank is consistent with the atmospheric pressure. The steam-water mixture in the radiator is discharged under the action of system pressure, and is released and condensed in the expansion tank to achieve gas-water separation.
When the thermal load of the Petrol Car engine decreases, the pressure in the cooling system gradually decreases, and the volume of coolant and residual gas in the system decreases. At this time, the steam valve of the water tank cover closes; when the pressure in the system reaches a certain degree of vacuum, under the action of the pressure difference, Then, the air inlet valve of the cover is sucked open, and the coolant in the expansion tank returns to the radiator upper water chamber along the steam condensation pipe under the action of the atmosphere, participating in the cooling cycle and keeping the liquid level in the tank constant.
Like all Petrol Car internal combustion engines, it is inevitable to have gas in the cooling system. However, when the accumulated gas exceeds a certain limit, it will have an adverse impact on the operation of the Petrol Car engine, such as causing a decrease in water pump flow, resulting in a decrease in cooling efficiency; Causes local overheating in the engine cylinder of Roewe Car, causing the engine's power to decrease, economy to deteriorate, and even failure to operate normally; in addition, when the engine of a Petrol Car is shut down in a hot state, the coolant stops circulating, and the overheated parts dissipate heat and cause the coolant to Local boiling. Under the above circumstances, the coolant will be lost. The combination of the expansion tank device and the water tank cover solves the problems of supplementary storage and leakage storage (recycling) of cooling system coolant. Therefore, long-term antifreeze and antirust liquid is used to Dongfeng Roewe Car are very suitable.
The expansion water tank device of the vehicle's cooling system is installed on the upper right part of the rear side of the radiator frame (according to the forward direction of the Petrol Car). The steam discharge pipe of the original radiator is connected to the steam inlet pipe of the expansion tank. The expansion water tank assembly is composed of a plastic box, a connecting plate stamped from a steel plate, a supporting plate, a plastic cover and a rubber seal. It should be noted that the radiator cover must be reliably sealed. If the seal is not tight and the internal vacuum of the cooling system cannot be established, the internal circulation compensation function will not be achieved.
In addition, pay attention to the ventilation holes on the expansion tank cover and sealing gasket not to be blocked and must be kept clear. Otherwise, the pressure difference will not be established and the coolant in the expansion tank will not flow back into the tank. When the expansion water tank is filled with coolant for the first time, 2/3 of the coolant should be filled into the expansion water tank to ensure the normal operation of the system.