UNUSUAL ENGINE SOUNDS AND NOISES
Unusual engine sounds and noises are classified according to how they are generated as described
below.
1. Sound that changes when the clutch pedal is operated
2.
Sound that is often heard while idling
3.
Sound that is often heard only at a certain engine speed
4.
Sound that is often heard in all engine speed ranges
Sound that changes when the clutch pedal is operated
I
Operation
I
Main causes
I
No change in the unusual sound when the
clutch pedal is depressed
I
Crankshaft thrust bearing seizure
Sound that is often heard while idling
Unusual sound stops when the clutch pedal is
depressed
I
Probable cause
Crankshaft
thrust
bearing,wear
2.
Transmission defect
Water pump bearing
defect
Oil seal noise
Camshaft thrust
direction play
Camshaft bearing
Valve and seat
contact defect
Valve lifter piece
contact or damage
valve rocker arm
Crankshaft thrust
direction play
Example of sound
Koto-koto
Go-go
Notes
Check by placing a sound scope on the water pump body.
Remove the V belt and try to rotate by hand. If it feels gritty
to your hand there is a bearing defect
Pour in engine oil from the outside of the oil seal or apply a
noise damper solution with compressed air
The sound gets smaller or stops
Check by placing a sound scope in the area of the timing
gear cover
Sound is heard clearly when the engine warms up
After the engine has warmed up and the engine speed
changes from idling to a high speed, the sound gets smaller
or stops
Check the sprocket gear deflection
Check by placing a sound scope on the camshaft bearing
When the engine reaches a high speed the sound gets
smaller
Adjust the valve clearance
Check by placing a sound scope in the area of the cylinder
head valve
The sound gets smaller or stops when the valve is raised
Check by placing a sound scope on the cylinder head
*
The sound is generated more easily when the push rod is
not turning
*
Remove the lifter and check the contact surface
The sound gets smaller or stops when engine oil is filled or
the position of the valve rocker arm is changed
Depress the clutch pedal and check
-
If the sound stops the play is large in the thrust direction
The play is eliminated when the clutch pedal is depressed
and the crankshaft is pushed to the front, so the sound stops
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