250+ TOP MCQs on Petrol Engine Fuel Supply System – Air Cleaners and Answers

Automotive Engine Auxiliary Systems Multiple Choice Questions on “Petrol Engine Fuel Supply System – Air Cleaners”.

1. Which among the following is a function of air cleaner when the engine back-fires?
a) Flame arrester
b) Diffuser
c) Flame arrester and Diffuser
d) Pressure reliever
Answer: a
Clarification: The Engine backfires, the air cleaner also acts as a flame arrester. However, resistance to the airflow which is increased as the air cleaner gets clogged with due to which the engine performance would get decreased.

2. Which among the following is a function of an air cleaner concerning the carburation system?
a) Reducing agent
b) Catalyst
c) Silencer
d) Ventilation
Answer: c
Clarification: The air cleaner acts as a silencer for the carburation system as it reduces the engine induction noise to an acceptable level. The air cleaner is the most important part as hundreds of cubic meters of air per hour are used by the engine of an automobile.

3. Which part of the engine does not rapidly wear due to impurities like dust?
a) Cylinder
b) Pistons
c) Rings
d) Camshaft
Answer: d
Clarification: The impurities like dust in the air cause very rapid wear of the engine, particularly the cylinder, piston, rings, valves, and guides. Whereas the camshaft is not part of the cylinder as the camshaft just helps in the valve timing.

4. When an air cleaner gets clogged with dirt. How are the airflow,Engine performance, and fuel consumption respectively?
a) Increase, sluggish, lower
b) Decrease, sluggish,higher
c) Increase, better, lower
d) Has no effect
Answer: b
Clarification: When the air cleaner gets clogged the airflow gets decreased, resulting in sluggish engine performance and higher consumption of fuel. Therefore, it should be cleaned regularly or replaced periodically for every 20,000kms.

5. Which among the following is an example ofan oil bath type air filter?
a) Thermostatic control of air cleaner
b) Light duty types of air cleaner
c) Heavy-duty type air cleaner
d) Thermostatic control of air cleaner light duty types of air cleaner
Answer: c
Clarification: Heavy-duty type air cleaner is also known as an oil bath type wherein the filter is saturated with oil. The air from the atmosphere enters through the circumferential gap and around the corner the air takes a turn and large particle impurities are left.

6. In which type of air filter at idling or cold start condition the incoming air is heated and then sent to the cleaner?
a) Heavy-duty type air cleaner
b) Light duty type air cleaner
c) Thermostatic control of air cleaner
d) Heavy-duty type air cleaner and Light duty type air cleaner
Answer: c
Clarification: In the modern engine the lean fuel-air is used to reduce the pollution due to which efficiency decreases, therefore, to remedy this the incoming air is heated and then sent to the air cleaner.

7. At what temperature in degree centigrade such that the bleed valve opening is maximum when the hot air supply is cut-off?
a) 10
b) 20
c) 30
d) 40
Answer: d
Clarification: At 40-degree Centigrade, the bleed valve opening is maximum when the hot air supply is cutoff and only outside air enters the carburetor. This is provided in modern engines to reduce air pollution.

8. Which material is used as a cleaning element in a light-duty type air cleaner?
a) Plastic
b) Metal
c) Cellulose
d) Both Plastic and metal
Answer: c
Clarification: The cleaning element consists of a cylindrical cellulose fiber material, over which is put a fine mesh screen to provide strength. The element is corrugated to increase the surface area exposed to the incoming air.

9. To increase which of the following the cleaning element is corrugated and exposed to the incoming air?
a) Temperature
b) Pressure
c) Surface area
d) Force
Answer: c
Clarification: The element is corrugated to increase the surface area exposed to the incoming air so that the resistance offered by the cleaner is reduced to a minimum. Sides of the element are sealed against dust. The air passes through the element and any dust contained is left outside.

10. In which type of air cleaner the filter element is saturated with oil?
a) thermostatic control of air cleaner
b) light dusty type air cleaner
c) heavy-duty type air cleaner
d) both thermostatic and light dusty type
Answer: c
Clarification: The heavy-duty type air cleaner is also called an oil bath type wherein the filter material is saturated with oil. Impinging on the surface of the oil relieves the air further of the impurities. The final cleaning is done by a filter and clean air is passed to the engine.

11. Which among the following is the correct air movement in a heavy-duty type air cleaner?
a) Inlet – circumferential gap – oil bath – filter
b) Inlet – filter – oil both – the circumferential gap
c) Inlet -oil bath – filter – the circumferential gap
d) Circumferential gap- inlet -oil bath – filter
Answer: a
Clarification: The flow of air starts through the inlet and passes through the circumferential gap where the airflow takes a turn and then the oil bath and the filter which is dipped in oil where the total impurities present in the air are removed.

12. Which among the following is used to mesh with the cleaning material in a light-duty type of air filter?
a) Mesh screen
b) Plastic
c) Polymer coating
d) Sheet metal
Answer: a
Clarification: The air cleaner consists of a cylindrical cellulose fiber material, over which is put a fine mesh screen to provide strength. The element is corrugated to increase the surface area exposed to the incoming air so that the resistance offered by the cleaner reduced to a minimum.

13. Which are the parts that get damaged when dirt enters the crankcase?
a) Heavy-duty type air cleaner
b) Light duty type air cleaner
c) Thermostatic control of air cleaner
d) Heavy-duty type air cleaner and Light duty type air cleaner
Answer: d
Clarification: If the dirty air enters the crankcase, it will contaminate the lubricating oil and ultimately damage the bearings and journals and decrease the service period of the lubrication system.