Engine Noise - Subaru 2002 IMPREZA Service Manual

ENGINE NOISE
Type of sound
MECHANICAL
Condition
22.Engine Noise
A: INSPECTION
Heavy and dull clank
High-pitched clank (Spark
knock)
Clank when engine speed is
medium (1,000 to 2,000 rpm).
Oil pressure is low.
Oil pressure is normal.
Sound is noticeable when
accelerating with an overload.
Sound is reduced when fuel
injector connector of noisy cyl-
inder is disconnected.
(NOTE9
Sound increases as engine
speed increases.
Regular clicking sound
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*)
Sound is not reduced if each
fuel injector connector is dis-
connected in turn. (NOTE*)
Gear scream when starting
Sound like polishing glass with
engine
a dry cloth
-
Squeaky sound
I
-
-
-
Rubbing sound
I
Hissing sound
~
Timing belt noise
-
Valve tappet noise
NOTE*:
Possible cause
Valve mechanism is defective.
Incorrect valve clearance
Worn valve rocker
Worn camshaft
Broken valve sDrina
Worn crankshaft main bearing
Worn connecting rod bearing (big end)
Loose flywheel mounting bolts
Damaaed enaine mountina
~~ ~~
~
Ignition timing advanced
Accumulation of carbon inside combustion chamber
Wrong spark plug
Improper gasoline
Worn crankshaft main bearing
Worn bearing at crankshaft end of connecting rod
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 gear
Worn camshaft journal bore in crankcase
Insufficient generator lubrication
Defective generator brush and rotor contact
Defective ignition starter switch
Worn pear and starter pinion
Loose drive belt
Defective water pump shaft
Loss of compression
Air leakage in air intake system, hoses, connections or mani-
folds
Loose timing belt
Belt contacting case/adjacent part
Incorrect valve clearance
When disconnecting the fuel injector connector, Malfunction Indicator Light (CHECK ENGINE light) illuminates and trouble code
is stored in ECM memory.
Therefore, carry out the CLEAR MEMORY MODE <Ref. to EN(D0HC TURBO)-49, OPERATION, Clear Memory Mode.> and
INSPECTION MODE <Ref. to EN(D0HC TURBO)-46, OPERATION, Inspection Mode.> after connecting the fuel injector con-
nector.
ME(D0HC TURBO)-96