2-39
2.6.2 Troubleshooting to Crankshaft Mechanism
Description
Damage Form
Trouble Symptom of
Component
Trouble Symptom of Vehicle
Remedy
Piston
Carbon deposit on the piston top
Engine overheats
Clear away carbon deposit
Carbon deposit in the piston ring
groove
The piston ring is seized in the
ring groove
Engine fails or is hard to start. Engine lacks
power. Thick blue smoke from the exhaust pipe
Do.
Scuffing or scratches on the surface
of piston skirt
Piston-to-cylinder clearance is
too large
Do.
Replace the piston
Seriously worn piston
Do.
Do.
Do.
Seriously worn piston ring groove
Piston ring-to-groove clearance
is too large
Thick blue smoke from the exhaust pipe
Do.
Excessively worn piston pin hole
Piston pin-to-hole clearance is
too large
Knocking sound of piston pin and of cylinder
Do.
Crank pin
Worn out
Radial and axial gap is too
large
Knocking sound of big end bearing
Replace the crankshaft/
connecting
Bearing
Excessive wear of needle bearing
Do.
Do.
Do.
Excessive wear or damage of
crankshaft bearing
Abnormal sound from the crankshaft bearing
Replace the bearing
Piston Ring
Piston ring is broken
Engine fails or is hard to start. Engine lacks
power. Thick blue smoke from the exhaust pipe
Replace the rings as a set
Piston ring is seriously worn
End or side gap is too large
Do.
Do.
Piston ring is out of elastic
Improper air-tightness of
piston-to-cylinder
Do.
Do.
Improper placing
Piston ring end gaps are not
staggered
Engine lacks power. Thick blue smoke from the
exhaust pipe
Offset the piston ring end gaps
Piston pin
Excessive wear
Piston pin-to-hole clearance is
too large
Piston pin slap
Replace the piston pin
Connecting
rod
Excessive wear of small-end hole
Piston pin-to-small end hole is
too large
Do.
Replace the connecting rod
Connecting rod is bent
Knocking of cylinder
Do.
Excessive wear of big-end hole
Radial and axial gap is too
large
Knocking sound of big-end bearing
Do.
