Subaru 1600 Service Manual page 118

ENGINE
Type of sound Condition Possible cause
High-pitched Sound is noticeable when accelerating
•
Ignition timing advanced.
metaJlic knock with an overload
•
Accumulation of carbon inside
(Engine knocking)
combustion chamber.
• Wrong spark plug.
•
Defective distributor vacuum
controJler.
•
Improper gasoline.
Metallic knock
Sound is reduced when spark plug in
• Worn crankshaft main bearing.
when engine speed noisy cylinder is shortened out.
• Worn bearing at crankshaft end
is medium (1,000
of connecting rod.
to 2,000 rpm).
Knocking sound Sound is reduced when spark plug in
• Worn cylinder liner and piston
when engine is noisy cylinder is shortened out.
ring.
operating under
•
Broken or stuck piston ring.
idling speed and
• Worn piston pin and hole at piston
engine is warm.
end of connecting rod.
Sound is not reduced if each spark plug
•
UnusuaJly worn valve lifter.
is shortened out in turn.
• Worn cam gear.
• Worn camshaft journal bore in
crankcase.
Squeaky sound
•
Insufficient alternator lubrication.
Rubbing sound
• Defective alternator brush and
rotor contact.
Gear scream when
•
Defective ignition starter switch.
starting engine.
•
Worn ring gear and starter pinion.
Sound like
•
Loose drive belt.
polishing glass
• Defective water pump shaft.
with a dry cloth
Hissing sound
•
Loss of compression.
•
Air leakage in air intake system.
hoses, connections or manifolds.
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