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Probable cause
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Example of sound
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Notes
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1
Check the installation condition of the intake manifold, air1
cleaner, etc.
Check by blocking the intake area with engine oil, grease
or a cloth
Sound that is often heard only at a certain engine speed
Probable cause
Belt slippage
Contact sound from
the alternator bearing
or brush
Piston side knock
Connecting rod
bearing knocking
sound
Crankshaft bearing
knocking sound
Piston pin knocking
sound
Cooling fan
imbalance
Flywheel installation
bolt looseness
Example of sound
Bun
Uwan
Notes
Sound is generated after suddenly accelerating from idle
Set the belt tension to the standard
Check the belt for wear. cracks and adhered oil
Remove the belt, turn by hand and check the sound
The knocking sound is loud when the engine is cold, anc
when the temperature gets higher the knocking sound gets
smaller or stops
The aluminum alloy piston expands more than the cylinder:
so the piston clearance gets smaller and the side knock
gets smaller
When nozzle injection is stopped, the sound changes and
generally gets smaller
Heard clearly from the bottom of the engine during or
immediately following acceleration after the engine has
warmed up
If nozzle injection is stopped at the engine speed where the
knocking sound is generated (about
1000
rpm), the sound
changes and generally gets smaller
Heard clearly from the bottom of the engine during or
immediately following acceleration after the engine has
warmed up
Sound does not change much even when nozzle injection
is stopped
Compared to the connecting rod bearing, this knocking
sound is a little lower and sharper
The sound gets louder when the engine warms up, and itis a
harder sound than the piston side knock
If nozzle injection is stopped at the engine speed where the
knocking sound is generated (about
1000
rpm), the knocking
soundchanges
When the belt is removed and the engine started, the sound
stops
Check the fan for bend, installation looseness and
deflection
Gets louder during sudden acceleration
The sound gets smaller or stops when the clutch pedal is
fully depressed
*
Very similar to the knocking sound of the crankshaft
bearing, .but is harder
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