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
Prevents a shocking hazard to the operator, ensuring safety during the test.
Avoids potential fire hazards by eliminating electrical sparks that could ignite fuel vapors.
Step 2
5.1.2 All spark plugs are removed.
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Ensures accurate compression readings by allowing air to exit unobstructed.
Allows the engine to turn over more easily, facilitating the compression test.
Step 3
5.1.3 The air filter is removed.
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Removes any restrictions to air flow into the cylinder, allowing for maximum intake.
Ensures that accurate readings can be obtained during the compression test.
Step 4
5.2 Explain in THREE steps how to calibrate a cylinder leakage tester.
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Connect the compressed air hose from the compressor to the tester to supply air.
Adjust the regulator valve knob to observe the gauge reading and ensure it’s within the desired parameters.
Stop turning the knob when the gauge reads 0%.
Step 5
5.3 State TWO functions of an exhaust gas analyser.
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Analyzes exhaust gasses to determine the emissions present.
Indicates the levels of CO, CO2, HC, NOx, SOx, and O2 to help assess 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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Bluetooth connection for wireless functionality.
Wi-Fi connection for remote diagnostics.
Cable connection for direct linking.
Step 7
5.5 Explain the difference between static and dynamic wheel balancing.
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Static wheel balancing refers to balancing the wheel when it is stationary, ensuring it remains still when at rest.
Dynamic wheel balancing involves balancing the wheel while it is in motion, which helps maintain stability while driving.
Step 8
5.6 Which THREE factors are used to locate a wheel's dynamic imbalance?
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The degree of imbalance, which indicates how far the wheel is off balance.
The extent of the unbalancing forces acting on the wheel.
The direction of these forces, determining whether adjustments should be made 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 to examine the readings provided.
Align the vertical line within the triangle by moving the pointer arm to ensure accuracy.
Take the degree reading on the toe gauge, noting whether it reads on the IN or the OUT side of the scale.
