Cylinder Liner; Cylinder Liner - Endoscopic Examination - MTU 12 V 4000 M73 x Operating Instructions Manual

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 150).
2. Remove injector (→ Page 153).
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.
Cylinder liner – Endoscopic examination
Findings
• Thin carbon coating on circumference of carbon scraper ring
• Slight localized additive deposits at top edge
Singular smooth areas at lower 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
•
damage
• Heat discoloration of piston rings
1. Compile endoscopy report using the table.
2. Use technical terms for description of the liner surface (→ Page 143).
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.
MS150045/02E 2013-07 | Task Description | 141
Part No. Qty.
Y20097353
Action
No action required
Further endoscopic examina-
tion required as part of mainte-
nance work
Cylinder liner must be replaced;
Service must be contacted
1