5.1 Give TWO reasons why EACH of the following precautions should be observed before a compression test:
5.1.1 The ignition system is disconnected - NSC Mechanical Technology Automotive - Question 5 - 2022 - Paper 1
Question 5
5.1 Give TWO reasons why EACH of the following precautions should be observed before a compression test:
5.1.1 The ignition system is disconnected.
5.1.2 All spark... show full transcript
Worked Solution & Example Answer:5.1 Give TWO reasons why EACH of the following precautions should be observed before a compression test:
5.1.1 The ignition system is disconnected - NSC Mechanical Technology Automotive - Question 5 - 2022 - Paper 1
Step 1
5.1.1 The ignition system is disconnected.
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Answer
To prevent a shocking hazard to the operator, ensuring safety while working on the engine.
To prevent fire hazards that can arise from sparking, protecting both the vehicle and technician.
Step 2
5.1.2 All spark plugs are removed.
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Answer
This ensures accurate readings by allowing the engine to turn freely without compression.
It facilitates easier starting of the engine during the test, enhancing testing efficiency.
Step 3
5.1.3 The air filter is removed.
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Removing the air filter allows maximum airflow into the cylinder, ensuring optimum testing conditions.
It also helps in obtaining more accurate readings during the compression test.
Step 4
5.2 Explain in THREE steps how to calibrate a cylinder leakage tester.
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Answer
Connect the compressed air hose from the compressor to the tester.
Adjust the regulator valve to the appropriate gauge reading as specified for calibration.
Stop turning the knob when the gauge reads 0%, indicating the calibration is complete.
Step 5
5.3 State TWO functions of an exhaust gas analyser.
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It analyses exhaust gasses to determine their composition.
It indicates the amounts of CO, CO2, HC, NOx, SO2, and O2 present, helping to diagnose engine performance.
Step 6
5.4 State THREE ways in which on-board diagnostic (OBD) scanners can be connected to a laptop or computer.
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Via Bluetooth connection.
Using Wi-Fi networking.
Through a physical cable connection.
Step 7
5.5 Explain the difference between static and dynamic wheel balancing.
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Answer
Static wheel balancing refers to balancing the wheel when it is stationary, focusing on weight distribution.
Dynamic wheel balancing, in contrast, considers the wheel's balance while in motion, accounting for uneven forces encountered while driving.
Step 8
5.6 Which THREE factors are used to locate a wheel's dynamic imbalance?
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The position of imbalance, whether it is on the inner or outer side of the wheel.
The extent of the unbalancing forces measured through weight distribution.
The direction of these forces, identifying if they are clockwise or counterclockwise.
Step 9
5.7 How do you obtain a reading for toe-in/toe-out, using the periscope optical alignment gauge, after it has been set up against the wheels?
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Look through the periscope gauge's optical viewfinder to examine the alignment.
Align the vertical line within the triangle against the pointer arm to check for indications.
Take the reading to determine the degree of toe-in or toe-out; ensure the reading is on the IN or OUT of the scale.
