MTU 20V4000M73 series, Operating Instructions Manual

Page: 139 / 252

7.3 Cylinder Liner
7.3.1 Cylinder liner – Endoscopic examination
Preconditions
☑
Engine is stopped and starting disabled.
Special tools, Material, Spare parts
Designation / Use Part No. Qty.
Rigid endoscope
Y20097353 1
Preparatory steps
1. Remove cylinder head cover (→ Page 148).
2. Remove injector (→ Page 152).
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 through the mount of the injector into the cylinder liner.
Cylinder liner – Endoscopic examination
Findings Measure
• Thin carbon coating around carbon scraper ring
• Minor localized additive deposits at top edge
• Localized smooth areas at bottom edge
• Carbon deposits on entire circumference in clearance area 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
• Flawless, even honing pattern
• First signs of marks left by lower cooling bores
• Running pattern seems darker
No action required
• 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 circum-
ference can not be faulted
• Piston rings can not be faulted
Further endoscopic examina-
tion required as part of mainte-
nance work
• On the entire circumference, apart from light areas of discoloration (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
Cylinder liner must be replaced,
contact Service.
1. Compile endoscopic report using the table.
2. Use technical terms for description of the liner surface (→ Page 139).
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.
MS150046/03E 2018-08 | Cylinder Liner | 137
TIM-ID: 0000000015 - 017