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7.2 Cylinder Liner
7.2.1 Cylinder liner – Endoscopic examination
Preconditions
☑ Engine is stopped and starting disabled
Special tools, Material, Spare parts
Designation / Use
Rigid endoscope
Preparatory steps
1.
Remove cylinder head cover (→ Page 89).
2.
Remove injector (→ Page 95).
Positioning crankshaft at BDC
1.
Using barring gear, turn crankshaft until crankshaft journal of the cylinder to be inspected has reached
BDC.
2.
Insert endoscope into cylinder liner through injector seat.
Endoscopic examination of cylinder liner
Findings
• Thin carbon coating on circumference of carbon scraper ring
• Slight localized additive deposits at top edge
• Localized smooth areas on bottom edge
• Carbon deposits on circumference in clearance between top piston
ring and bottom edge of carbon scraper ring
• First signs of marks left by top piston ring
• Bright mark on entire circumference
• Consistent honing pattern without objections
• First signs of marks left by lower cooling bores
• Running pattern seems darker
• Dark areas with even or varying degrees of discoloration
• Beginning and end of the discoloration are not sharply defined and
do not cover the entire stroke area
• Dark areas in the upper section of the cooling bore, remaining cir‐
cumference without objections
• Piston rings without objections
• On the entire circumference, apart from light areas of discoloration
(that do not impair operation) clearly darker stripes that start at the
top piston ring
• Heat discoloration in the direction of stroke and honing pattern dam‐
age
• Heat discoloration of piston rings
1.
Compile endoscopy report using the table.
2.
Use technical terms for description of the liner surface (→ Page 81).
3.
Depending on findings:
• do not take any action or
• carry out a further endoscopic examination as part of maintenance work or
• contact Service; cylinder liner must be replaced.
78 | Task Description | MW15407/14E 2012-02
Part No.
Qty.
Y20097353
Action
No action required
Further endoscopic examina‐
tion required as part of main‐
tenance work
Cylinder liner must be re‐
placed; Service must be con‐
tacted
1
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