Flushing the cooling system

Over time, the water passages of the radiator and engine narrow or even become completely clogged with scale or deposits, reducing the efficiency of the cooling system. In this case, the coolant acquires a dark rusty color and flushing of the entire system is required. If the blockage is severe, countercurrent flushing may be required.

1. Disconnect the top hose from the radiator, then insert the water hose and flush the radiator with a circulating stream until the water flowing from the drain hole is clean and clear. For better flushing, disconnect the lower hose from the radiator.

2. If the system is heavily clogged, it should be flushed with countercurrent. To do this, remove the radiator, turn it over and insert the hose into its outlet. Flush until the water flowing from the filler hole is clear.

3. The engine should also be flushed. To do this, remove the thermostat. Insert a hose into the water passage leading from the thermostat housing to the cylinder head and continue flushing until the water flowing from the cylinder block drain plug and from the bottom hose is clear. Also disconnect and flush the hoses leading to the carburetor or intake manifold (depending on design).

4. Chemical cleaners should only be used as a last resort. Regular replacement of the coolant prevents contamination of the system.