As a second engineer, inspecting a cylinder liner and piston assembly is an important maintenance task. The procedure begins with examining the cylinder liner. First, inspect for any carbon accumulation around the scavenge ports, clean them thoroughly, and check for damage, such as cracks. Then, ensure the liner's internal surface is smooth; any signs of burns or protruding metal should be addressed using an oil stone or portable grinder as per recommendations. Pay special attention to the quill areas for corrosion or cracks, and manually pump oil to ensure all quills are functioning correctly. Additionally, inspect the liner for honing marks; the absence of these and the presence of a mirror finish indicate lubrication failure. Black patches on the liner surface suggest leaking piston rings, which need replacement. It's also essential to measure the cylinder liner wear and compare it to previous records, ensuring the wear rate is within the manufacturer's limits. If the liner is withdrawn, examine the water side for scale or deposits and clean as necessary. Also, check the condition of the O-rings and renew them if needed.

The piston assembly inspection involves checking for burns at the top of the piston, wear on the side walls of the crown, and ring grooves. Look for any cracks due to thermal or mechanical stresses, high-temperature corrosion, or sulfuric acid corrosion. Ensure the piston rings move freely, and check the ring grooves for wear, steps, and scuffing. If the piston is water-cooled, inspect the underside for scaling, or if oil-cooled, check for carbon deposits. Finally, inspect bolts, locking wires, studs, and O-rings for integrity.

1. Cracks due to hoop stress because of poor liner support
2. Circumferential cracks along the wear ridge due to stress concentration or, more likely, because of new rings hitting the ridge
3. Cracks in the shape of a star due to flame impingement in combustion space
4. Cracks in the shape of stars around the lubricating quills due to water leaking
5. Corrosive wear leading to clover leafing near the lubricating quills injection
6. Cracks across the scavenge port due to overloading, poor cooling, scavenge fire, etc
7. Excessive wear of liner surface due to friction, corrosion, adhesion or abrasion and improper lubrication
8. Mirror finish of liner surface due to lubrication failure

Possible piston faults:

• Cracks on piston due to thermal and mechanical stresses
• Excessive wear down of piston rings and grooves due to insufficient lubrication and poor combustion leading to carbon deposits
• Burning of piston crown due to fuel impingement
• Breaking of piston rings due to excessive clearance
• Fouling of piston cooling water/ oil space due to scale deposits

• Ensure proper lubricating oil supply and proper lubrication
• Proper maintenance of fuel injector and fuel system to ensure no flame impingement after burning etc
• Correct grade of fuel oil to be used with minimum impurities and proper purification
• Ensure proper cooling of liner and correct jacket water temperature to be maintained to avoid thermal stress
• Inspection and maintenance of piston and liner at regular intervals to prevent faults
• Correct tightness of bolts and nuts
• Proper treatment of jacket cooling water
• Lube oil analysis at regular intervals

Inspection of Cylinder Liner:

1. Clean the liner thoroughly.
2. Take accurate measurements and calibrate liner wear.
3. Check for cracks (fatigue, thermal, or superficial).
4. Examine for glazing or highly polished surfaces.
5. Inspect oil lubricator holes for blockages or uneven wear.
6. If liner is excessively polished, carry out honing.
7. Inspect and clean scavenge ports from any carbon deposits.
8. Check for ridge formation at the Top Dead Centre (TDC) area.
9. Inspect the anti-polishing ring and calibrate it.
10. Calculate liner wear down and record.

Inspection of Piston Assembly:

1. Clean the piston thoroughly and remove all carbon deposits.
2. Observe piston rings in position before removal.
3. Remove piston rings, clean grooves, and take groove measurements.
4. Calculate piston crown burn-out.
5. Inspect piston crown, skirt, and ring lands for cracks.
6. Dismantle piston to inspect piston cooling spaces.
7. Check for coking of oil passages.
8. Replace sealing rings (O-rings) of cooling pipes.
9. Inspect for internal cracks in crown or skirt.
10. Reassemble piston and carry out hydraulic test on cooling spaces.
11. Measure and calibrate piston ring wear.

• Maintain correct cylinder oil dosage and ensure proper grade of oil is used.
• Carry out regular honing of liners to avoid polishing and glazing.
• Ensure fuel oil treatment (purification, heating, filtration) is effective to prevent deposits.
• Monitor and maintain lubricator performance to avoid blocked oil holes.
• Avoid prolonged operation with high exhaust temperatures and load fluctuations.
• Regular inspection and maintenance of piston rings, grooves, and anti-polishing rings.
• Carry out scavenge port cleaning at scheduled intervals.
• Conduct periodic hydraulic testing of piston cooling spaces.
• Ensure timely replacement of worn components (liners, rings, piston crowns).