8.1 Answer the following questions with reference to an exhaust gas analysis - NSC Mechanical Technology Automotive - Question 8 - 2021 - Paper 1
Question 8
8.1 Answer the following questions with reference to an exhaust gas analysis.
8.1.1 State TWO causes of a low CO₂ exhaust gas reading.
8.1.2 State TWO corrective m... show full transcript
Worked Solution & Example Answer:8.1 Answer the following questions with reference to an exhaust gas analysis - NSC Mechanical Technology Automotive - Question 8 - 2021 - Paper 1
Step 1
State TWO causes of a low CO₂ exhaust gas reading.
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Answer
Too rich air/fuel mixture.
Ignition misfire or blown cylinder head/block.
Step 2
State TWO corrective measures for the causes stated in QUESTION 8.1.1.
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Answer
Reset the fuel mixture.
Correct the cause of the ignition misfire by replacing the cylinder head or block.
Step 3
State TWO exhaust gas readings, as detected by a gas analyser, which are caused by a lean air/fuel mixture.
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Answer
High oxygen (O₂) levels.
High carbon dioxide (CO₂) levels.
Step 4
State ONE cause and ONE corrective measure for the following cylinder leakage test results:
8.3.1 Hissing sound at the exhaust pipe.
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Cause: Leaking exhaust valve.
Corrective measure: Replace the exhaust valve.
Step 5
State ONE cause and ONE corrective measure for the following cylinder leakage test results:
8.3.2 Bubbles in the radiator water.
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Answer
Cause: Blown cylinder head gasket.
Corrective measure: Replace the cylinder head gasket.
Step 6
Explain why an internal combustion engine should be at normal operating temperature when diagnostic tests are performed.
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Answer
An internal combustion engine should be at normal operating temperature to allow for the proper expansion of components, ensuring accurate diagnostic readings and optimal operational conditions.
Step 7
Complete the table below by writing down the question numbers (8.5.1 to 8.5.4) and the answer in the ANSWER BOOK.
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Answer
8.5.1: Replace fuel filter.
8.5.2: Remove or disconnect and blow out fuel lines.
8.5.3: Clean the strainer.
8.5.4: Check and correct the voltage to the pump.
Step 8
State THREE manufacturer’s specifications required before an oil pressure test can be done.
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Answer
Oil pressure when engine is cold.
Oil pressure when engine is hot.
Oil pressure during idle.
Step 9
Explain FOUR steps to perform a radiator cap pressure test.
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Answer
Obtain the radiator cap's opening pressure specifications (stamped on the cap).
Install the cap onto the adapter of the cooling system pressure tester.
Pump up the tester while watching the pressure gauge.
