Draining and filling coolant (Peugeot 306)

The cooling system has two separate drain plugs, both of which must be open. First, open the expansion tank cap, and then open or unscrew the cap on the bottom of the radiator. The liquid is drained into a container placed underneath. The engine should not be hot when opening the plugs. There may be a small nipple on the radiator drain plug (in figure 397 on the right, marked with the corresponding symbol).
In this case, connect a small hose to drain the liquid into a container placed underneath. The engine should not be hot when unscrewing the plugs. The coolant is drained into a container provided. The work is done in the open air. The drained liquid is disposed of in accordance with the instructions.
To drain the coolant from the engine, open the plug on the cylinder block.
Loosen the expansion tank mount and drain the coolant from the tank. Temporarily place the expansion tank aside in the engine compartment.
If the coolant has been used in the engine for a long time, it is necessary to flush the cooling system. To do this, connect a water hose to the radiator opening. Run water through the hose until clean water begins to flow out of the plug holes and the lower radiator nipple.
Prepare the antifreeze mixture based on the expected outside temperatures. A mixture of 35% antifreeze and 65% water is suitable for operation at normal subzero temperatures (down to approximately -15°C). A mixture of 50% antifreeze and 50% water ensures the cooling system operates at temperatures down to -35°C. When purchasing antifreeze, specify that it is suitable for use in diesel engines.
Tighten both drain plugs or connect the radiator hose. It is essential to ensure sealing.
Open the air release valves. On all engines these valves are located in the locations indicated on figure 397. They are marked in the figure with the corresponding symbol.
Reinstall the expansion tank if it was removed.
Pour coolant into the expansion tank opening until a continuous stream appears from the air release valve opening. After this, tighten the valves in the following order: radiator, engine, heater.
Check again that the drain plugs and air release valve are closed. If the air bleed valve bolt is loose, the engine cannot be started.
Start the engine and let it run at 1500 to 2000 rpm until the fan turns on and then off (or fans). After this, let the engine idle for about another minute.
Turn off the engine and wait about 10 minutes. Check the coolant level in the expansion tank and replace the cap. The coolant level in the expansion tank should reach the "Max" mark. If not, top up with coolant.