ME(H4SO)-95
MECHANICAL
Engine Noise
23.Engine Noise
A: INSPECTION
NOTE*:
When disconnecting the fuel injector connector, Malfunction Indicator Light illuminates and DTC is stored in ECM memory.
Therefore, carry out the CLEAR MEMORY MODE <Ref. to EN(H4SO)(diag)-47, OPERATION, Clear Memory Mode.> or <Ref.
to EN(H4SOw/oOBD)(diag)-28, OPERATION, Clear Memory Mode.> and INSPECTION MODE <Ref. to EN(H4SO)(diag)-40,
OPERATION, Inspection Mode.> or <Ref. to EN(H4SOw/oOBD)(diag)-26, OPERATION, Inspection Mode.> after connecting
fuel injector connector.
Type of sound Condition Possible cause
Regular clicking sound
Sound increases as engine
speed increases.
• Valve mechanism is defective.
• Incorrect valve clearance
• Worn valve rocker
• Worn camshaft
• Broken valve spring
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
• Wrong spark plug
• Improper gasoline
Clank when engine speed is
medium (1,000 to 2,000 rpm).
Sound is reduced when fuel
injector connector of noisy cyl-
inder is disconnected.
(NOTE*)
• 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 cyl-
inder is disconnected.
(NOTE*)
• 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 dis-
connected in turn. (NOTE*)
• Unusually worn valve lifter
• Worn cam gear
• 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
—
• Loose drive belt
• Defective water pump shaft
Hissing sound —
• Loss of compression
• Air leakage in air intake system, hoses, connections or mani-
folds
Timing belt noise —
• Loose timing belt
• Belt contacting case/adjacent part
Valve tappet noise — • Incorrect valve clearance
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