The most likely reason for the formation of an airlock in a cooling system is the non-tightness of the Nissan Almera Classic cylinder head.
You can diagnose the air traffic jam by blowing up the cooling fluid in the expansion bar and flowing the cooling radiator. Even the new heat sink can begin running immediately after the replacement. The oil that gets the cooling liquid is also bubblin '.
The air traffic jam may occur after a thermostat or cooling radiator has been replaced. It is better to fix it quickly, as it can lead to a hydroshock and engine destruction.