I. Read the text and describe the cooling system operation.
The primary job of the cooling system is to cool the engine and to keep it from overheating. Another important
job of the cooling system is to allow the engine to heat up as quickly as possible and then to keep.
II.Scan the text to get the answers to these questions.
1. Why does the engine become very hot?
2. How much energy pushes the pistons?
3. What are the two functions of the cooling system?
4. How are motorcycles usually cooled?
5. What increases the efficiency of air-cooling?
6. Why is liquid-cooling preferred to air-cooling in large engines?
7. Where is hot fluid cooled in the car engine?
8. What liquids are used in the cooling system?
9. What requirements must the coolant meet?
III.Read the text attentively for more details about cooling systems.
When you drive a car, the engine becomes very hot. Why?
Burning in the engine the fuel-air mixture produces energy. But only a quarter of this energy makes the
pistons move. Most of it turns into heat. About half of this heat goes down the exhaust pipe and the other half
stays in the engine making it very hot. In fact, the cooling system on a car driving down the freeway dissipates
enough heat to heat two average-sized houses! The primary job of the cooling system is to cool the engine and
to keep it from overheating. However, the cooling system also has several other important jobs. The engine in
your car runs best at a fairly high temperature. When the engine is cold, components wear out faster, and the
engine is less efficient and emits more pollution. So, another important job of the cooling system is to allow the
engine to heat up as quickly as possible, and then to keep the engine at a constant temperature. There are two
types of cooling systems found on cars: air-cooled and liquid-cooled.
Some older cars, very few modem cars and most motorcycle has air-cooled engines. Constructing the engine
block covered in numerous external aluminum fins engineers greatly increase its surface area, which can be
cooled by the flow of air passing over it. A powerful fan is used to supply an increased amount of air for
cooling multi-cylinder engines. The forced airflow conducts heat away from the cylinders radiating it into the
air more efficiently.
However, it is difficult to design large engines with an unobstructed airflow over all the cylinders. The
alternative is a liquid (water)-cooling system.