.liner inspection   .li

Preparation: 

1. Permission to be granted to immobilize the engine
2. Propeller clearance to be obtained
3. Block starting air mechanism
4. Engage turning gear, open indicator cocks
5. Stop necessary p/p’s and v/v’s
6. Drain water and shut all v/v’s
7. Permit to work with risk assessment carefully done
8. Tool box meeting to be carried out
9. All tools must be arranged before the inspection
10. Remove the cylinder head

Safety precaution:

i.  Ladder should be properly hung

ii.  Safety harness must be worn

iii.  Adequate lighting must be arranged

iv.  Nothing should be hanging from overhead crane.

Inspection procedure:  

With piston removed, or bring the piston to BDC for liner inspection

Special attention to be given to check for:

1. Check the surface of gasket sitting area
2.  Ridge formation at TDC position
3. Flow of oil from lubrication ports
4. Cracks and damage at lubrication openings
5. Clover leafing – corrosive wear between the lubricator ports if the cylinder oil cannot neutralize the acid products of combustion
6. Mechanical friction wear marks and abrasive wear on the liner surface
7. Dark areas of liner indicating blow-by
8. Corrosion in liner surface – Acidic and cold corrosion
9. Scuffing and scoring marks of liner surface
10. Glazing of liner surface (mirror finish)
11. Cracks on the surface and near scavenge port openings
12. Sharp edgy surface of scavenge ports
13. Liner calibration to check the liner ovality and wear 
14. If it exceeds the limit, the liner should be renewed. for slow speed maximum allowable wear is 0.8-1% of the bore. 
15. For medium speed engine maximum 0.7% of the bore

Discuss the ideal location of lubricating quill on a liner

1. Not near port areas oil can be scraped and blown away
2. Not near high temperature zone or the oil will burn easily
3. Should be located in such area points to ensure even and complete coverage as possible

In between piston rings (1^st &2^nd) with the piston at TDC, piston ring will spread oil effectively.