Subaru 2009 IMPREZA Service Manual page 1166

MECHANICAL
26.Engine Noise
A: INSPECTION
Type of sound
Regular clicking sound
Heavy and dull clank
High-pitched clank
Clank when engine speed is
between 1,000 and 2,000
rpms.
Knocking sound when engine
is operating under idling speed
and engine is warm
Squeaky sound
Rubbing sound
Gear scream when starting
engine
Sound like polishing glass with
a dry cloth
Hissing sound
Timing belt noise
Valve noise
(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)-54, OPERATION, Clear Memory Mode.> and Inspec-
tion Mode <Ref. to EN(H4DOTC)(diag)-43, PROCEDURE, Inspection Mode.> after connecting the fuel injector connector.
Engine Noise
Condition
Sound increases as engine
speed increases.
Oil pressure is low.
Oil pressure is normal.
Sound is noticeable when
accelerating with an overload
condition.
Noise is reduced when fuel
injector connector of noisy cyl-
inder is disconnected.
(NOTE*)
Noise is reduced when fuel
injector connector of noisy cyl-
inder is disconnected.
(NOTE*)
Sound is not reduced if each
fuel injector connector is dis-
connected in turn. (NOTE*)
—
—
—
—
—
—
—
ME(H4DOTC)-108
Possible cause
• Valve mechanism is defective.
• Incorrect valve clearance
• Worn camshaft
• Broken valve spring
• Worn crankshaft main bearing
• Worn connecting rod bearing (large end)
• Loosened flywheel mounting bolt
• Damaged engine mounting
• Ignition timing advanced
• Accumulation of carbon inside combustion chamber
• Wrong heat range of spark plug
• Improper octane value gasoline
• Worn crankshaft main bearing
• Worn connecting rod bearing (large end)
• Worn cylinder liner and piston ring
• Broken or stuck piston ring
• Worn piston pin and hole at piston end of connecting rod
• Unusually worn valve lifter
• Worn cam sprocket
• Worn camshaft journal bore in cylinder head
Insufficient generator lubrication
Poor contact of generator brush and rotor
• Defective ignition starter switch
• Worn gear and starter pinion
• Loose V-belt
• Defective water pump shaft
• Insufficient compression
• Air leakage in air intake system, hose, connection or manifold
• Loose timing belt
• Timing belt contacting with adjacent part
Incorrect valve clearance