Deck 9: Automotive Engine Lubrication and Cooling System

Question 1

The knock in diesel engine occurs due to

A)instantaneous and rapid burning of the first part of the charge
B)instantaneous atuo iginition of last part of charge
C)delayed burning of the first part of the charge
D)reduction of delay period

Answer 1

instantaneous and rapid burning of the first part of the charge

Question 2

A stoichiometric air-fuel ratio is

A)chemically correct mixture
B)lean mixture
C)rich mixture for idling
D)rich mixture for over loads

Answer 2

chemically correct mixture

Question 3

Mechanical efficiency is the ratio of

A)brake power to heat input
B)indicated power to heat input
C)brake power to indicated power
D)friction loss to heat input

Answer 3

brake power to indicated power

Question 4

Most commonly used lubrication system in automobiles is the

A)splash system
B)pressure system
C)petrol system
D)gravity system

Question 5

Friction that occurs between the layers of oil film is called

A)viscous friction
B)greasy friction
C)dry friction
D)boundary friction

Question 6

Crankcase ventilation, is provided

A)to cool cylinder
B)to cool crankcase
C)to cool piston
D)to remove blow by

Question 7

the most important property of the lubricant is

A)density
B)viscosity
C)thermal conductivity
D)none of the above

Question 8

The maximum pressure in the lubrication system is controlled by

A)oil pump
B)oil filter
C)valve relief
D)supply voltage

Question 9

The lubricants commonly used in the automobiles are

A)animal oils
B)vegetable oils
C)mineral oils
D)cooking oils

Question 10

Detergents are oil additives used to

A)reduce viscosity
B)increase fire point
C)prevent sludge formation
D)prevent foaming

Question 11

Oil pressure in the dry sump lubrication system is around

A)5 bar - 10 bar
B)11 bar 15 bar
C)3 bar - 8 bar
D)1 bar

Question 12

For mep decreases when using

A)single cylinder engine
B)smaller number of larger cylinders
C)larger number of smaller cylinders
D)none of the above

Question 13

With increase in compression ratio, mechanical efficiency

A)increases
B)decreases
C)remains constant
D)compression ratio has nothing to do with ?mech

Question 14

Blow by losses are

A)directly proportional to the inlet pressure
B)inversely proportional to the inlet pressure
C)proportional to the square root of inlet pressure
D)none of the above

Question 15

Mist lubrication system is mainly used in

A)four-stroke petrol engine
B)four-stroke diesel engine
C)two-stroke petrol engine
D)Wankle engine

Question 16

Additives are added in lubricant to have

A)detergent-dispersant characteristics
B)pour point depression
C)antifoam characteristics
D)all of the above

Question 17

The principal surfaces requiring lubrication in an IC engine are

A)cylinder head
B)crankcase
C)inlet and exhaust manifold
D)none of the above

Question 18

The heat given to cooling medium in IC engines is about

A)50-60%
B)30-40%
C)10-20%
D)60-70%

Question 19

Radiator is provided to

A)cool the jacket water
B)pressurise the cooling water
C)provide additional water flow
D)none of the above

Question 20

Thermostat is used in radiators to

A)control the velocity of water
B)control distribution of water to various cylinders
C)control the water temperature
D)control the pressure of water

Question 21

As the compression ratio increases, there is a

A)large increase in heat rejection
B)large decrease in heat reduction
C)marginal increase in heat rejection
D)marginal reduction in heat rejection

Question 22

Spark timing other than minimum spark advance for best torque (MBT) results in

A)less heat rejection
B)more beat rejection
C)no effect on heat rejection
D)none of the above

Question 23

Direct system of cooling air is one which

A)cooling water flows by gravity
B)hot water is continuously cooled and circulated
C)hot water is simply discharged
D)water is allowed to evaporate in the cylinder jacket

Question 24

In evaporate cooling systems, heat absorbed per kg of coolant air is equal to

A)Cp ? t
B)Cv ? t
C)latent heat of the coolant
D)(Cp - Cv) ? t

Question 25

Pump used in the forced cooling system is normally

A)piston pump
B)gear pump
C)vane pump
D)centrifugal pump