OVERHEATING IN CARS

Last week Friday I hanged out with some of my friends and had a lot of fun but on our way home one of my friend car started to overheat while we were waiting for the temperature of his car to cool down it started to rain all we could do was to sit put and chat during our conversation I could not help but notice that he kept calling is mechanic to ask what he could do so I thought to myself if my friend does not know what to do when is car overheated that means a lot of people out there does not know what to do too.
So that why this posting is about proper diagnose of overheating and what you should do.
First:
Check if there is enough coolant in the radiator? Don't just look inside the plastic overflow bottle, but remove the radiator cap (when the engine is cold) and look inside the radiator. You should be able to physically see the fluid level if it is at its proper level. Most cars and trucks will hold 1 ½ - 2 gallons of coolant and water mixture. If you have to add more than a pint of fluid you should have the cooling system pressure tested for a leak. If you see any obvious fluid loss on the ground or in the engine compartment, you should also have the system tested for leaks.
Second:
If no coolant leak or low fluid level is present, then determine when the overheating complaint occurs if the engine overheats while at a stop or idle only:
Most front wheel drive cars use an electric cooling fan motor located in front or behind the radiator. The function of the cooling fan is to improve airflow across the radiator at stops and low speeds. The fan is controlled by sensors that regulate the engine temperature and additional load that might be placed on the engine.
The air conditioning compressor will require the cooling fan to operate at idle as long as the compressor is on. A quick way to check the cooling fan operation is to turn on the air conditioner. The cooling fan should come on with the air conditioner compressor. Some cars will have two electric fans, one is for the radiator and the other is the air conditioner condenser fan. Usually the radiator fan is closer to the middle of the radiator. The radiator fan is responsible for engine cooling, and the condenser fan is responsible for increasing air conditioning efficiency at idle and low speed.
If your vehicle does not have an electric cooling fan on the radiator it will have a belt driven fan blade and fan clutch. This fan should be pulling a large amount of warm to hot air across the radiator onto the engine. What you want to determine with either fan situation is that there is ample airflow across the radiator at idle. The radiator is the primary heat exchange for the engine, and airflow is crucial.
When the engine overheats while at high speeds on the freeway?
Again, airflow and coolant circulation are crucial. At 100km/h we can assume you have ample airflow across the radiator, so proper coolant circulation is the thing to inspect. Let’s compare overheating at 100km/h to jogging with a sock in your mouth. The faster and longer you jog, the more air you are going to require, and with a sock in your mouth you are going to have to breath extra hard to maintain the proper amount of air to keep you going. At 100km/h the water pump is pumping a large amount of hot coolant throughout the cooling system.
If there is a restriction in the system like a kinked radiator hose, a restricted radiator, or a stuck thermostat, it will produce the same affect as the sock in the mouth scenario. Rust and water calcification can accumulate in the radiator and drastically reduce the flow of coolant at high speeds. Removing the radiator from the vehicle for disassembly and cleaning or radiator replacement are the only two real cures for a clogged radiator.
Using a can of "radiator flush" additive might help as preventive maintenance, but will probably just be a waste of time and money trying to correct a restricted radiator.