If the engine has a cylinder block drain plug, it is necessary to remove the drain plug and drain the residual coolant in the cylinder block. When there is no coolant flowing out, tighten the drain valve and the cylinder block drain plug. Slowly inject new antifreeze into the water tank until it reaches the highest mark. Turn the heater control button to the heating position, start the engine until the radiator outlet pipe becomes hot, and then turn off the engine. Finally, check the liquid level of antifreeze, and replenish it if the liquid level does not reach the highest mark.
BMW's water tank is the heat exchanger of water-cooled engine, which makes the automobile engine work in the normal range through air convection cooling. If the engine cooling water in BMW's water tank boils, vaporizes and expands, when the engine pressure of BMW exceeds the set value, the water tank cover overflows to release the pressure, reducing the cooling water and preventing the cooling system pipeline of the automobile from bursting. Maintenance points of BMW water tank are as follows:
1. The radiator of BMW water tank must not contact with any acid, alkali or corrosive substances. It is recommended to use soft water, and soften hard water before use to avoid internal blockage and scaling of radiator.
2. When using antifreeze, in order to avoid radiator corrosion, please be sure to use long-term antirust antifreeze produced by regular manufacturers and in line with national standards.
3. In the process of installing the BMW 730 radiator, please don't damage the radiator belt (sheet) and bump the radiator to ensure the heat dissipation ability and sealing performance. When the radiator is completely drained before adding water, turn on the drain switch of the engine cylinder first, and then turn it off when there is water flowing out to avoid blisters.
(Photo/Text/Photo: Pacific Auto Network Q&A called Beast)