Cooling spaces can be examined by the following methods:

• Borescope / endoscope inspection
• Inserted through cooling-water inlet/outlet connections or inspection plugs to visually check for:
  • Scale formation
  • Corrosion
  • Cracks
• Hydrostatic pressure test
• The jacket-water system is pressurised to the specified test pressure to detect:
  • Leakage
  • Hairline cracks
  • Weak joints
• Cooling-water analysis
• Monitoring pH value, chloride content and iron content gives an indication of:
  • Internal corrosion
  • Possible liner or jacket leakage
• Temperature monitoring
• Abnormal temperature rise or uneven temperature distribution indicates:
  • Blocked cooling passages
  • Scale build-up
• Flow-rate comparison
• Reduced or uneven jacket-water flow suggests:
  • Fouling
  • Partial blockage of cooling passages
  Part (b)

  Parts of the cylinder jacket to be inspected after removing an old liner (before fitting a new liner)

  After removal of the liner, close attention should be given to the following areas:

  • Liner landing faces (upper and lower)
  • Check for:
    • Cracks
    • Fretting
    • Distortion
    • to ensure correct seating of the new liner.
  • Cooling-water spaces
  • Inspect for:
    • Scale
    • Rust
    • Sludge
    • and clean thoroughly to restore efficient heat transfer.
  • O-ring grooves / sealing faces
  • Examine for wear, corrosion or damage that could lead to cooling-water leakage.
  • Tie-rod holes and stud seating areas
  • Look for cracking or deformation due to stress concentration.
  • Cylinder jacket bore
  • Check for ovality, corrosion pitting or erosion that may prevent correct liner alignment.
  Part (c)

  Periodic attention to the scavenge air space and piston-rod packing (stuffing box)

  Scavenge air space

  • Regular cleaning
  • Remove oil sludge, carbon deposits and debris to reduce the risk of scavenge fires.
  • Inspection of scavenge drains
  • Ensure drains are clear and effective to prevent oil accumulation.
  • Checking scavenge ports
  • Look for signs of:
    • Broken piston rings
    • Scuffing
    • Excessive oil carry-over
  • Fire detection and safety devices
  • Inspect scavenge fire flaps, drains and alarm systems for correct operation.

  Piston-rod packing (stuffing box)

  • Inspection of sealing and scraper rings
  • Ensure effective separation between:
    • Scavenge air space
    • Crankcase oil
  • Leakage checks
  • Excessive leakage indicates worn rings or incorrect ring tension.
  • Drain condition monitoring
  • Observe drain oil for contamination, which may indicate stuffing-box ring failure.