8.1 State THREE manufacturers' specifications that could be used to conduct an oil pressure test - NSC Mechanical Technology Automotive - Question 8 - 2019 - Paper 1
Question 8
8.1 State THREE manufacturers' specifications that could be used to conduct an oil pressure test.
8.2 Give TWO reasons why an exhaust pressure test is conducted.
8... show full transcript
Worked Solution & Example Answer:8.1 State THREE manufacturers' specifications that could be used to conduct an oil pressure test - NSC Mechanical Technology Automotive - Question 8 - 2019 - Paper 1
Step 1
State THREE manufacturers' specifications that could be used to conduct an oil pressure test.
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Answer
Oil pressure at engine idle speed. Manufacturers often specify the required oil pressure while the engine is at rest to ensure optimal lubrication.
Oil pressure when the engine is cold. This helps determine the oil viscosity and flow properties under cold conditions.
Oil pressure on high revolutions. It's crucial to know the oil pressure at higher RPMs to ensure proper engine performance.
Step 2
Give TWO reasons why an exhaust pressure test is conducted.
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Determine if the catalytic converter is blocked. A blockage can lead to increased back pressure, affecting engine performance and efficiency.
Identify a decrease in power output. Monitoring exhaust pressure can reveal issues within the exhaust system contributing to power loss.
Step 3
Explain how a pressure test is conducted on a radiator cap.
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Install the cap on the cooling system pressure tester. This ensures a proper seal for the test.
Increase the pressure in the tester while observing the pressure gauge. Watch for any drops in pressure which would indicate a fault.
Check the pressure release. The cap should release pressure at a specified value to ensure it maintains operation within designed limits.
Step 4
List FOUR manufacturer's specifications that must be obtained before a fuel pressure test can be carried out.
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Fuel pressure before fuel pump. This ensures the system can adequately supply fuel.
Fuel pressure at idle speed. Knowing this helps assess engine performance at low RPM.
Fuel pressure at high revolutions. This indicates how well the fuel system performs under load.
Fuel pressure before the injectors pump. Critical for ensuring even distribution to the engine's cylinders.
Step 5
Remove the high-tension lead.
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This step prevents electrical shock and ensures safety while working on the vehicle's ignition system.
Step 6
Unplug the fuel-injection system.
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This is done to prevent unburned fuel from entering the exhaust system and to stop fuel from entering the cylinders, thus avoiding potential engine damage.
Step 7
Open the throttle valve fully.
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Opening the throttle allows for maximum air intake, ensuring accurate readings during the compression test.
Step 8
Record the readings.
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The readings obtained during the compression test are essential for evaluating the condition of the engine and determining if the piston rings are worn.
Step 9
Explain how a wet compression test is conducted on an internal combustion engine after a dry compression test has been done on the engine.
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Add oil to the cylinder low on reading. This allows testing of the cylinder’s seal and the condition of the piston rings.
Conduct a compression test again. By comparing the wet test results to the dry compression tests, it can determine if the piston rings are indeed worn.