Subaru IMPREZA GD 2007 Series Manual page 2502

asieps_tobira_IM_US.book 101 ページ ２０１２年１月１７日 火曜日 午後３時４８分
26.Engine Noise
A: INSPECTION
Type of sound
Regular clicking sound
Heavy and dull clank
High-pitched clank
Clank when engine speed is
1,000 to 2,000 rpm
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)-53, OPERATION, Clear Memory Mode.> <Ref. to
EN(STI)(diag)-48, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)(diag)-43, PROCEDURE,
Inspection Mode.> <Ref. to EN(STI)(diag)-39, PROCEDURE, Inspection Mode.> after connecting the fuel injector connector.
Engine Noise
Condition
• Valve mechanism is defective.
Sound increases as engine • Incorrect valve clearance
speed increases. • Worn camshaft
• Broken valve spring
• Worn crankshaft main bearing
Oil pressure is low.
• Worn connecting rod bearing (large end)
• Loosened flywheel mounting bolt
Oil pressure is normal.
• Damaged engine mounting
• Ignition timing advanced
Sound is noticeable when
• Accumulation of carbon inside combustion chamber
accelerating with an overload
• Wrong heat-durability spark plug
condition.
• Improper octane value gasoline
Sound is reduced when fuel • Worn crankshaft main bearing
injector connector of noisy • Worn connecting rod bearing (large end)
cylinder is disconnected.
(NOTE*)
Sound is reduced when fuel • Worn cylinder liner and piston ring
injector connector of noisy • Broken or stuck piston ring
cylinder is disconnected. • Worn piston pin and hole at piston end of connecting rod
(NOTE*)
Sound is not reduced if each • Unusually worn valve lifter
fuel injector connector is • Worn cam sprocket
disconnected in turn. (NOTE*) • Worn camshaft journal in cylinder head assembly
— • Insufficient generator lubrication
— • Poor contact of generator brush and rotor
• Defective ignition starter switch
—
• Worn gear and starter pinion
• Loose drive belt
—
• Defective water pump shaft
• Insufficient compression
—
• Air leakage in air intake system, hose, connection or manifold
• Loose timing belt
—
• Belt contacting with case/adjacent part
— • Incorrect valve clearance
ME(H4DOTC)-101
MECHANICAL
Possible cause