Subaru 2006 Legacy, Manual

Page: 2273 / 4302

ME(H4DOTC)-94
Engine Noise
MECHANICAL
26.Engine Noise
A: INSPECTION
NOTE*)
When disconnecting the fuel injector connector, the malfunction indicator light illuminates and DTC is stored in ECM memory.
Therefore, perform the Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-42, OPERATION, Clear Memory Mode.> and Inspec-
tion Mode <Ref. to EN(H4DOTC)(diag)-33, PROCEDURE, Inspection Mode.> after connecting the 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 camshaft
• Broken valve spring
Heavy and dull clank
Oil pressure is low.
• Worn camshaft main bearing
• Worn connecting rod bearing (large end)
Oil pressure is normal.
• Loosened flywheel mounting bolt
• Damaged engine mounting
High-pitched clank
Sound is noticeable when
accelerating with an overload
condition.
• Ignition timing advanced
• Accumulation of carbon inside combustion chamber
• Wrong spark plug
• Improper gasoline
Clank when engine speed is
between 1,000 and 2,000 rpm.
Sound is reduced when fuel
injector connector of noisy cyl-
inder is disconnected.
(NOTE*) • Worn camshaft 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 sprocket
• Worn camshaft journal bore in cylinder head
Squeaky sound — Insufficient generator lubrication
Rubbing sound — Poor contact of generator brush and rotor
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 —
• Insufficient compression
• Air leakage in air intake system, hose, connection or manifold
Timing belt noise —
• Loose timing belt
• Belt contacting with case/adjacent part
Valve tappet noise — Incorrect valve clearance
asieps_tobira.book 94 ページ ２００９年１０月２６日 月曜日 午前９時１６分