Which risk increases when an engine piston's oil control ring fails to effectively scrape oil from cylinder walls?

💡 Explanation

When the oil control ring fails, excess oil enters the combustion chamber because the lubrication system no longer effectively manage film thickness, leading to carbon deposits on the spark plug and piston crown, causing pre-ignition. Therefore pre-ignition risk increases rather than detonation, bearing failure or coolant boiling which require unrelated system faults.

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