Engine Safety (Supplementary) USCG Question #734 (Set 9)

A diesel engine emits blue exhaust smoke as a result of __________.

Official USCG Answer & Rule Citation

Correct Answer: Option C — excessive cylinder lubrication

Blue exhaust smoke indicates lubricating oil burning within the combustion chambers. This is typically caused by excessive cylinder lubrication, worn scraper rings, or defective valve guide seals allowing oil to pass into the gas stream.

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