|
Type
of sound
|
Condition
|
Possible
cause
|
Regular
clicking sound
|
Sound
increases as engine speed increases.
|
|
•
|
Valve mechanism
is defective.
|
|
•
|
Incorrect valve clearance
|
|
Heavy and dull clank
|
Oil
pressure is low.
|
|
•
|
Worn crankshaft
main bearing
|
|
•
|
Worn connecting rod bearing (big end)
|
|
Oil
pressure is normal.
|
|
•
|
Loose flywheel
mounting bolts
|
|
•
|
Damaged engine mounting
|
|
High-pitched
clank (Spark knock)
|
Sound
is noticeable when accelerating with an overload.
|
|
•
|
Ignition
timing advanced
|
|
•
|
Accumulation of carbon inside combustion chamber
|
|
Clank
when engine speed is medium (1,000 to 2,000 rpm).
|
Sound
is reduced when fuel injector connector of noisy cylinder is disconnected.
|
|
•
|
Worn crankshaft
main bearing
|
|
•
|
Worn bearing at crankshaft end of connecting rod
|
|
Knocking sound when engine is operating under idling speed and
engine is warm
|
Sound
is reduced when fuel injector connector of noisy cylinder is disconnected.
|
|
•
|
Worn cylinder
liner and piston ring
|
|
•
|
Broken or stuck piston ring
|
|
•
|
Worn piston pin and hole at piston end of connecting
rod
|
|
Sound
is not reduced if each fuel injector connector is disconnected in
turn.
|
|
•
|
Unusually
worn valve lifter
|
|
•
|
Worn camshaft journal bore in crankcase
|
|
Squeaky
sound
|
—
|
|
•
|
Insufficient
generator lubrication
|
|
Rubbing
sound
|
—
|
|
•
|
Defective
generator brush and rotor contact
|
|
Gear
scream when starting engine
|
—
|
|
•
|
Defective
ignition starter switch
|
|
•
|
Worn gear and starter pinion
|
|
Sound
like polishing glass with a dry cloth
|
—
|
|
•
|
Defective water pump shaft
|
|
Hissing
sound
|
—
|
|
•
|
Air leakage in air intake system, hoses, connections
or manifolds
|
|
Timing
belt noise
|
—
|
|
•
|
Belt contacting case/adjacent part
|
|
Valve
tappet noise
|
—
|
|
•
|
Incorrect
valve clearance
|
|
