There are a couple of safety issues to keep in mind while working on a radiator. These include the temperature of the radiator, the temperature of the water and the handling of the waste water. When the cooling system is pressurised (which it is when the engine is hot), any air in the system is compressed. Removing a radiator cap when the system is under pressure will release this hot air from the opening. If you must take the radiator cap off it's a good tip to firstly turn the cap a quarter of a turn only. This will let the steam out and limit the amount of coolant escaping, be very careful this can lead to serious burns. The safest option is to wait until the radiator has cooled down before working on it to minimise the risk of being burnt.
When draining a cooling system, the used coolant must be captured in a bucket and disposed of correctly. Coolant contains toxins that are harmful to the environment and poisonous if ingested. Care should be taken when handling this waste water,
only transport in sealed containers; it is advisable you contact your local council on the location of a facility to take the waste water.
In order for coolant to properly absorb heat from the engine and prevent overheating, it must remain below a certain temperature. Check your vehicles owners' manual on the specific type of coolant to use in your cooling system. There are many different additives in coolant so it is very important to use the correct one. Some additives protect alloy and others may stop your water from freezing so be sure to check because radiators are responsible for transferring heat from a vehicle's coolant to the outside air.
Some manufacturers provide radiator caps with temperature gauges built into them. Cap gauges are useful in case of temperature sensor failure. Also, being able to read an approximate temperature while the vehicle is operating provides information about how effectively the coolant is absorbing heat and how hot the engine is running. When driving it is a good practise to no your vehicles operating temperature in relation to the temperature gauge, if the temperature gauge raises suddenly you no you may have a problem in your cooling system.