Auto Mechanics Questions and Answers 2017 (WAEC GCE NECO) | Expo Runz
Presently, this is the past questions and answers for WAEC GCE 2017/2018 for September/October, NECO GCE Nov/Dec, WAEC May/June. As a matter of fact, the WAEC Answers that appears below is for study purpose only. It is not intended for expo Answers 2017/2018. Now read on...
WAEC GCE Auto Mechanics Questions and Answers 2017 | Expo Runz
Question 1
(1) (a) List two types of lubricant used in an automobile industry.
(b) Name the lubricant used in two parts of each of the following systems:
- steering;
- suspension;
- transmission.
(c)
(i) State the meaning of SAE written on oil containers.
(ii) Explain the term SAE 20W/50.
(d) Name one tool used for greasing.
Observation
Almost all the candidates attempted this question.
They performed well in parts (a) and (d) of the question.
However their responses to parts (b) and (c) were not satisfactory.
The required responses to these parts are:
(b) Two typical parts on which each lubricant is used in the
(i) Steering system include:
- grease used on ball joints, kingpins, front hub assembly and steering rack and pinion;
- gear oil or transmission oil used in steering gearbox.
(ii) Suspension system include:
- grease used on lower arms, upper arms and spring shackles;
- penetrating oil used on leaf springs.
(iii) Transmission system include:
- grease used on universal joints and propeller shafts;
- gear oil, transmission or lubricating oil used on gearbox and rear-axle.
(c) (i) S.A.E mean Society of Automotive Engineers
(c) (ii) The term SAE 20W/50 refers to a multi-grade oil which resists thickening when the temperature decreases i.e. very cold temperature and thinning when the temperature increases i.e. at high temperature.
Question 2
(a) List two types of engine cooling system.
(b) Sketch one of the types listed in 2 (a) above.
(c) State two merits of each of the cooling systems.
Observation
Most of the candidates who attempted this question were able to provide the required responses to parts (a) and (b) of the question. The only difficult part was part (c) of the question. The required response to this part is:
(c) Merits of air-cool engine include:
- it is simple in construction;
- it has light weight;
- it is cheaper;
- it does not freeze;
- it is free from leakage;
- it warms up quickly;
- air is readily available;
- there is not topping up of the cooling system.
Merits of water-cool engine include
- there is reduced mechanical noise;
- temperature of various engine parts are more uniform;
- improved thermal efficiency;
- cylinders can be placed closer together or it is more compact;
- the engine can operate under critical condition.
Question 3
(a) Check Below
- Sketch an insulated return system of a motor vehicle wiring.
- State two advantages of the earth return system over the insulated return system of a motor vehicle wiring.
(b) State one function each of the following:
- alternator;
- regulator;
- solenoid switch;
- starter motor.
Observation
Candidates who attempted this question faired well in parts (a i), (b i) and (b iv) . Parts (a ii), (b ii) and (b iii) were extremely difficult for them. The required responses to parts (a ii), (b ii) and (b ii) are:
(aii) Advantages of the earth return system over the insulated return system of a motor vehicle wiring are:
- reduced cable length;
- cost of wiring is reduced;
- simplified wiring;
- faults are easier to trace;
- neat arrangement.
(bii) Regulator controls the rate of charge from the generator thus ensuring constant current for the electrical and electronic parts.
(biii) Solenoid switch connects the battery, ignition switch and starter motor together thus causing the engine to start
Question 4
(a) Identify the type of single-cylinder engine shown below
(b) Identify the parts labeled V, W, Y and Z.
(c) State the purpose of the parts labeled, V, W and Z.
(d) Explain how the engine shown in 4 (a) is lubricated.
Observation
This question was extremely difficult for the candidates as they could not provide the required responses to the various parts of the question. The required responses to the various parts of the question are:
4. (a) It is a two-stroke, spark-ignition engine or two-stroke petrol engine.
It is also called a two-stroke valveless engine or two-stroke three-port engine.
(b)
V – deflector;
W – transfer port;
Y – exhaust port;
Z – crankcase.
(c) The purpose of V is to direct the charge up thus preventing its escape. W is to allow the partially compressed charge pass to the upper part of the piston while Z allows for partial compression of the fresh charge or it accommodates the engine rotating parts.
(d) It employs a system of lubrication called petroil where the recommended quantity of oil is mixed with petrol to lubricate the internal parts of the engine.
Question 5
The sketch below is a leaf spring unit.
(a) Identify the parts labeled J, K, L, M and N.
(b) State the purpose of the following:
(i) swinging shackles;
(i) centre bolt.
(c) State three advantages of an independent suspension over the rigid type.
Observation
Most of the candidates who attempted this question faired well in part (c) of the question. However parts (a) and (b) were not properly responded to by the candidates. The required responses to parts (a) and (b) are;
- J is Master leaf, main leaf or top leaf;
- K is U – bolt;
- L is Spring eye or eye;
- M is Axle;
- N is spring clip or clip.
(i) Swinging shackle allows a variation in the spring length
(ii) Centre bolt is used to fasten the leaves together.
Candidates' Weakness and Suggested Remedies
- Candidates’ weaknesses were shown in their inability to:
- name the lubricant used in the steering, suspension and transmission system;
- explain the term SAE 20W/50;
- state the function of regulator and solenoid switch;
- state the advantages of the earth return system over the insulated return system of a motor vehicle wiring.
SUGGESTED REMEDY FOR OVERCOMING WEAKNESSES
In order to overcome the above stated weaknesses, candidates were advised to study seriously before sitting for the examination. They were also advised to familiarize themselves with sketches of various components of a motor vehicle.
Candidates' Strength
Candidates’ strengths were shown in their ability to:
- list the types of lubricants used in automobile industry;
- name the tool used for greasing;
- sketch the types of engine cooling system;
- state the function of alternator and starter motor;
- sketch the insulated return system of a motor vehicle wiring
General Comments
The standard of the paper compared favourably with those of precious years as the questions were clear and within the scope of the syllabus. However the performance of the candidates was poorer when compared to that of last year.
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