Flushing the engine block
Refill the system with clean water. Run the engine up to its normal working temperature and check for leaks.
Disconnect the top hose from the short tube on the thermostat housing above the pump.
Loosen the top of the case and lift the thermostat to see which method it is suitable for. Reinstall the top of the empty shell.
Seal the garden hose into the housing. Rinse until the water is removed from the bottom hose. This is back flushing: water usually flows on the engine.
If you remove the heat sink, reinstall the heat sink and put it back in the thermostat. After applying both sides with an uncured sealant, install a new gasket in the thermostat housing.
Reconnect the hose and replace any damaged hoses or clips or any hose that has been in use for more than four years.
Replenish the system with clean water. Run the engine to normal operating temperature and check for leaks.
Add antifreeze only when you are satisfied that there are no leaks.
Even in the summer, use an antifreeze mixture - it contains antiseptic additives. Ordinary tap water can cause rapid corrosion and partial blockage of the cooling system.
The coolant mixture is usually suitable for winter and summer use for two to three years and should be replaced afterwards.
Cleaning radiator fins
Brush loose dirt from the fins of the radiator core with a nylon brush - not a wire brush, as the soft metal core is easily damaged. Do not poke it with a wire or a screwdriver.
If the core looks oily, spray it with a proprietary oil dispersant or apply an oil solvent with a soft brush.
Protect the electrics, then hose water through the fins from back to front.