MTU 12V 2000 G23, Use And Maintenance Manual

Page: 144 / 214

6 – 04 Cylinder Liner
6.2 Cylinder Liner
6.2.1 Cylinder-liner endoscopic examination
Preconditions
• Engine is stopped and starting disabled.
Special tools
Designation / Use Part No. Qty.
Rigid endoscope, max. diameter: 7 mm
Preparatory steps
1. Remove cylinder-head cover (
→
Page 6 – 13).
2. Remove injector (
→
Page 6 – 19).
Bringing the piston to BDC position
1. Use the barring tool to rotate the crankshaft until the crank pin of the cylinder to be inspected is at BDC position.
2. Insert the endoscope through the cylinder-head injector bore into the combustion chamber.
Findings Task
• Thin carbon deposits around the carbon-residue control ring
• Light, localized additive deposits on upper surface
• Polished spots on lower edge
• Ring of oil deposits in the area between the positions of the upper
piston-ring and the lower edge of the carbon-residue control ring
• Start of traces left by upper piston ring
• Bright surface round circumference
• Even honing pattern without complaint
• Start of traces left by lower cooling-oil bores
• Wear pattern appears to be darker
No measures necessary.
• Oxidation discoloration of even or uneven intensity.
• Start and end of discolored areas have no clear edges and do not
extend over the whole stroke length
• Discolored areas become lighter in upper part of cooling bore; rest of
circumference without complaint
• Piston-ring set without complaint
Further endoscope check
necessary during maintenance
work.
• In addition to bright discolorations (which are not critical for engine
operation), evidently darker "black zones" all over the running surface,
beginning at upper-piston-ring TDC position
• Overheating discoloration in piston stroke direction with damaged
honing pattern
• Piston rings show overheating discoloration
Cylinder liner must be replaced.
Contact Service.
Cylinder-liner endoscopic examination
1. Assess findings of endoscopic examination using the above table.
2. For description of findindings on cylinder liner surface use the specified terms (
→
Page 6 – 06).
3. Depending on the findings:
• Do not take any measures, or
• Conduct endoscopic examination of another liner in the course of maintenance work; or
• Contact Service: Cylinder liner must be replaced.
M015560 / 00E 03-05 © MTU