Marine Diesel Engine 2 Cylinder Liner - Problems, Analysis & Maintenance

VOCABULARY flashcards covering the components, damage types, causes, and maintenance of cylinder liners in 2-stroke marine diesel engines.

Cylinder Liner

A precisely machined, replaceable sleeve that forms the inner wall of the combustion chamber in a two-stroke marine diesel engine.

Abrasion

Mechanical wear from hard particles embedded between piston rings and the liner surface that scratch and erode the metal like sandpaper.

Catalytic fines (Cat fines)

Extremely hard $Al_2O_3$ and $SiO_2$ particles found in heavy fuel oil that act as a major abrasive wear agent.

Cold Corrosion

Chemical attack by sulphuric acid ($H_2SO_4$) that occurs when the liner wall temperature drops below the acid dew point, approximately $130\text{--}150^{\circ}C$.

Scuffing

Adhesive wear (metal-to-metal contact) caused by the breakdown of the lubricating oil film, leading to localized frictional welding or micro-seizure.

Total Base Number (TBN)

A measure of the alkalinity in cylinder oil; TBN 70 is used for high-sulphur fuels (3–4%), while TBN 20–40 is for low-sulphur fuels.

Cloverleafing

A non-uniform corrosive wear pattern forming a lobed cross-section, resulting from uneven distribution of cylinder oil alkalinity.

Honing

A surface finishing process performed to improve oil retention, aid in ring sealing, and prevent wear by keeping the liner and piston working smoothly.

Asperities

Metal surface peaks on the piston ring and liner wall that come into direct contact and cause micro-welding when the oil film fails.

Profilograph

A specialized instrument used to measure the non-uniform wear pattern known as cloverleafing.

Thermal shock

A root cause of liner cracking characterized by rapid metal contraction due to sudden cooling, such as cold water hitting a hot liner.

Bore gauge

Also known as an internal micrometer, this tool is used to measure the liner bore diameter at specific axial positions.

Wear Rate Formula

$$\text{Wear Rate} = (\text{Increase in bore diameter}) \div (\text{Running hours}) \times 1000\, [\text{mm / 1000 hrs}]$$

Replacement threshold

The limit at which a liner must be replaced, typically when wear reaches $0.6\text{--}0.8\%$ of the bore diameter.

Liner Material

Alloyed cast iron containing chromium, molybdenum, and vanadium for enhanced wear and thermal resistance.