2. Drain the coolant, install the lower hose, or close the drain plug, and fill the system with fresh water. Install the radiator cap, start the engine and warm it up to normal operating temperature, then stop and (after waiting until it cools down completely) drain the system again. Repeat as necessary until clean water flows from the system. Finally, fill the system with the specified coolant mixture.
3. If the mixture specified has been used and replaced at the intervals specified, the above procedure will be sufficient to keep the system clean for a considerable time. If these recommendations have been neglected, a more thorough flush must be performed as follows.
4. Before flushing the system, first drain the coolant as described in previous chapter.
5. Disconnect the upper hose from the thermostat housing and disconnect the lower hose (if not already disconnected) from the radiator outlet pipe.
6. Insert a garden hose into the top hose and run water through the radiator until it runs clear out the bottom outlet.
7. To flush the engine, remove the thermostat as described in Chapter 11, insert a garden hose into the thermostat housing. Run water through the engine until it runs clear out of the bottom hose. Finally, install the thermostat.
8. In case of serious contamination, you can use back flushing of the radiator. To do this, remove the radiator as described in Chapter 9, turn it over and insert a garden hose into the bottom outlet. Rinse until clear water runs out of the top hose outlet.
9. Chemical filters may only be used when absolutely necessary. Regular replacement of antifreeze prevents excessive contamination of the system.