Saturday, May 13, 2006

good motoring
Cool ride in the heat
H.Kishie Singh

Well, summer is already here and it is important for both you and your car to keep cool. As you ride around in your air-conditioned car, spare a thought for the engine. The radiator is responsible for the well-being of your car as it keeps the car cool. It must function to 100 per cent efficiency, failing which a lot of things can go wrong. Find out if your car’s coolant is fresh? Coolant must be changed every year. It loses its efficiency over a period of time which heats up the engine.

Heat exchanger will be a better word if we have to explain the function of the radiator.

The engine block gets extremely hot while running, basically due to friction of the moving parts. The engine is supposed to run hot at a particular temperature to make use of the energy generated. Only about 25 per cent of the power of the engine is available to run the car, the rest is turned into heat and is removed by the radiator – or heat exchanger. The rest is pure waste, it goes out of the tail pipe.

The engine block, which has the pistons and cranks, generates the most heat and, therefore, is the hottest part of the engine. At the time of manufacturer, channels that allow coolant to flow through are built in the block. As the coolant flows through these channels, it absorbs the heat and then flows into the radiator to be cooled. Water boils at 100ºC. With coolant the boiling temperature is raised to say 120ºC. So, the chances of water boiling, burning into steam and evaporating are minimal.

The radiator cap that has a very tight fit aids the cooling process. This makes the radiator more efficient, like a pressure cooker.

If you used just water with a loose-fitting radiator cap, the water would evaporate and the radiator would get empty. This was common in the older cars. You could see cars stranded on the roadside, bonnet open, waiting for the engine to cool off. Thankfully, this is a thing of the past.

The word coolant is a little misleading. Not only does it raise the boiling point of the water, it also lowers the freezing point. It could make the freezing point –20ºC, a temperature you are hardly likely to encounter. In addition to having anti-boil and anti-freeze properties, the coolant also has anti-corrosive properties. Rusting radiators are also a thing of the past.

All these properties are possible because of the additive glycol. Two of the most common “coolants” used are ethylene glycol or propylene glycol because they are easily water soluble.

A word of caution. The radiator does get blocked by dust, mud and wheat-straw. The recommended way to clear the radiator is to blow compressed air from the rear. This makes sure that the foreign objects lodged in the vanes or fins, exit the way they entered.

It is a common practice to wash the radiator with a high-pressure water hose from the front. This will only lodge dust and mud in the fins, reducing their efficiency. The force of the water may also bend the fins, causing permanent damage and, again, reducing the cooling efficiency of the radiator.

To help the engine maintain an optimum operating temperature, there is a thermostat somewhere in the engine. You’ll never see it, but it is there. Keep a watch on the temperature gauge, it will show the same reading, summer or winter. Any change and you should head for the service station. Happy motoring!