NSC Mechanical Technology Automotive CI engines, injectors, and valve assemblies: With reference to the engine cyl

With reference to the engine cylinder compression test, answer the following questions: 5.1.1 Give a reason for conducting the test - NSC Mechanical Technology Automotive - Question 5 - 2023 - Paper 1

Question 5

With-reference-to-the-engine-cylinder-compression-test,-answer-the-following-questions:--5.1.1-Give-a-reason-for-conducting-the-test-NSC Mechanical Technology Automotive-Question 5-2023-Paper 1.png

With reference to the engine cylinder compression test, answer the following questions: 5.1.1 Give a reason for conducting the test. 5.1.2 Name TWO types of compre... show full transcript

Worked Solution & Example Answer:With reference to the engine cylinder compression test, answer the following questions: 5.1.1 Give a reason for conducting the test - NSC Mechanical Technology Automotive - Question 5 - 2023 - Paper 1

Step 1

5.1.1 Give a reason for conducting the test.

96%

114 rated

Answer

The engine cylinder compression test is conducted to assess the functionality and health of the engine's cylinders. Specifically, it allows us to determine the amount of compression loss from a specific cylinder, which indicates if there are issues such as worn compression rings or damaged cylinder walls.

Step 2

5.1.2 Name TWO types of compression tests.

99%

104 rated

Answer

Dry Test: This test measures the cylinder pressure without any additional lubrication or fluids introduced into the cylinder.
Wet Test: In this test, oil is added to the cylinder before taking the measurement, which can help identify if the low compression is due to worn piston rings.

Step 3

5.1.3 Give TWO reasons for low compression in a cylinder.

96%

101 rated

Answer

Worn or cracked cylinders can lead to loss of compression as gases escape.
Worn or broken piston rings can also contribute to decreased compression as they fail to create a proper seal.

Step 4

5.2.1 Label components A–D.

98%

120 rated

Answer

A - Pressure control valve / knob - regulator B - Gauge / Meter C - Compressor hose / air hose / pipe D - Spark plug connector / adapter / hose / pipe

Step 5

5.2.2 Why is pressurised air blown into the cylinder during the cylinder leakage test?

97%

117 rated

Answer

Pressurised air is blown into the cylinder to help identify leaks in various components, such as the valves, piston rings, or gaskets. By observing where the air escapes, a technician can determine the source of compression loss.

Step 6

5.3 State THREE precautions when performing an exhaust gas analysis.

97%

121 rated

Answer

The inlet hose must not be stepped on or restricted in any way to ensure accurate readings.
The hose connections must be airtight to prevent any leakages, which could alter the analysis results.
It is important to conduct the test in a well-ventilated area to avoid inhalation of harmful exhaust gases.

Step 7

5.4 Name THREE vehicle systems that can be scanned by the on-board diagnostic scanner.

96%

114 rated

Answer

Powertrain Control Module (PCM)
Transmission Control Module (TCM)
Engine Control Module (ECM)

Step 8

5.5 State TWO faults which could be identified while performing dynamic wheel balancing.

99%

104 rated

Answer

The extent of the imbalance in the wheel, which may lead to uneven tire wear or handling issues.
The run-out of the wheel assembly, which could affect vehicle stability.

Step 9

5.6 Describe in THREE steps how to perform dynamic wheel balancing after a wheel has been checked and set up on the wheel balancer.

96%

101 rated

Answer

Start the balancer and allow the wheel to spin freely to measure any imbalances.
Obtain the imbalance readings and note their locations on the wheel to identify where adjustments are needed.
Fit the correct weights to the specified locations on the wheel to even out the imbalance.

With reference to the engine cylinder compression test, answer the following questions: 5.1.1 Give a reason for conducting the test - NSC Mechanical Technology Automotive - Question 5 - 2023 - Paper 1

Worked Solution & Example Answer:With reference to the engine cylinder compression test, answer the following questions: 5.1.1 Give a reason for conducting the test - NSC Mechanical Technology Automotive - Question 5 - 2023 - Paper 1

5.1.1 Give a reason for conducting the test.

5.1.2 Name TWO types of compression tests.

5.1.3 Give TWO reasons for low compression in a cylinder.

5.2.1 Label components A–D.

5.2.2 Why is pressurised air blown into the cylinder during the cylinder leakage test?

5.3 State THREE precautions when performing an exhaust gas analysis.

5.4 Name THREE vehicle systems that can be scanned by the on-board diagnostic scanner.

5.5 State TWO faults which could be identified while performing dynamic wheel balancing.

5.6 Describe in THREE steps how to perform dynamic wheel balancing after a wheel has been checked and set up on the wheel balancer.

Join the NSC students using SimpleStudy...