Pic. 10. Expansion tank of the cooling system (the arrow shows the filler cap of the engine cooling system)
Since the expansion tank of the cooling system is made of opaque material, to check the fluid level in the system, it is necessary to unscrew the tank screw at the top of the radiator (pic. 10). In this case, the engine must be stopped, and its temperature must be above 50°C. Coolant should be visible in the expansion tank. Before the onset of the first night frosts, it is necessary to check the concentration of antifreeze (freezing temperature not higher than -30°С) through the filler cap of the radiator expansion tank. More information on this subject can be found in sect. «Cooling system».
Attention! The expansion tank cap may be opened when the coolant temperature is below 90°C. First, the cork is turned to the first latch, a short pause is made to release steam, and then only fully opened. To make up for small losses of coolant, plain water should be used. Completely decalcified, rainwater, distilled or demineralized water should not be used, as they promote corrosion. If a large amount of coolant has leaked out of the cooling system on the way, never add cold water to a hot engine so that the cylinder head is not deformed or cracked due to thermal stress. A small amount of cold water can also be added to a hot engine.