Bubbles inside the radiator expansion bottle were observed during a cylinder leakage test. Name ONE possible cause and also ONE corrective measure for the fault.
About this question
Question 8.2 of Mechanical Technology (Automotive) Grade 12, NSC Preparatory Examination (Eastern Cape DoE, September 2025). It tests the Term 2 ATP topic Maintenance (Specific) Diagnosing faults using test equipment such as gas analyzers, compr.
- TermTerm 2
- ATP topicMaintenance (Specific) Diagnosing faults using test equipment such as gas analyzers, compr
- PaperNSC September 2025 (Eastern Cape)
- Marks2 marks
Answer
2 marksPossible cause: a blown cylinder head gasket or a cracked cylinder block.
Corrective measure: skim the cylinder head and replace the head gasket, or replace the cylinder block.
Study this in your textbook: CAPS Annual Teaching Plan, Grade 12, Term 2: Materials, Forces, and Drive Trains.
More Questions On Maintenance (Specific) Diagnosing faults using test equipment such as gas analyzers, compr
Answer
The highest reading is 11 bar (cylinder 1) and the lowest is 8,2 bar (cylinder 3).
\[ \text{Variation} = 11 - 8{,}2 = 2{,}8\ \text{bar} \]As a percentage:
\[ \frac{11 - 8{,}2}{11} \times 100 \]\( 2{,}8\ \text{bar} = 25{,}45\,\% \)
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Three safety requirements when setting up a gas analyser are:
- The inlet hose must not be stepped on or restricted in any way.
- The hose connection must be airtight, with the condenser valve in the closed (horizontal) position.
- The vehicle tested must have no leaks in the exhaust, manifolds or vacuum system.
Answer
Two corrective measures are:
- Remove the cylinder head and rework or replace the valves.
- Fit a new cylinder head gasket (the head can also be skimmed and pressure tested).
Answer
Three possible areas of leakage are:
- The radiator core, neck or tanks.
- The flexible rubber hoses.
- The water pump.