Crankcase, Crankshaft And Main Bearing - Disassemble And Inspect - Mitsubishi S12A2 Service Manual

Chapter 5 DISASSEMBLY OF BASIC ENGINE

5. Crankcase, Crankshaft and Main Bearing - Disassemble and Inspect

Understanding of the current engine condition before disassembling is very important to know the cause of trouble and do the
efficient work.
Depending on the maintenance work or purpose, it is desirable to inspect some of the following items before proceeding with
any job.
Crankshaft End Play - Measure
Oil jet pipe bend,
deformation
Scale deposit, flaw,
crack, oil hole clogging
Valve operation,
oil hole clogging
Inner and outer peripheral
face flaw, corrosion, flaking
Wear, flaw, crack
4
Inner and outer
peripheral face flaw,
corrosion, flaking
Crankcase, Crankshaft and Main Bearing - Disassemble and Inspect
Disassembling Sequence
1 Main bearing cap bolt
2 Side bolt
3 Main bearing cap
4 Lower main bearing
5 Lower thrust plate
5-22
Wear
10
9
3
Local contact, crack on counterbore,
fretting/corrosion on fitting bore of
cylinder liner
11
Replace
Flaw
2
8
Peeling, wear, contact
7
Wear
Crack
Flaw
6 Crankshaft (Approx. 300 kg [661 lb.])
7 Upper main bearing
8 Upper thrust plate
9 Check valve
10 Piston cooling nozzle
11 Crankcase (Approx. 1010 kg [2227 lb.])
6
5
1