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Home >> Subaru >> 2017 >> WRX Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 28 (Engine Mechanical System) >> Engine Noise >> Inspection

Engine Noise: Inspection

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.
Type of sound Condition Possible cause
Regular clicking sound Sound increases as engine speed increases.
  • Valve mechanism is defective
  • Incorrect cam clearance
  • Worn camshaft
  • Broken valve spring
  • Defective valve shim
Heavy and dull clank Oil pressure is low.
  • Worn crankshaft bearing
  • Worn connecting rod bearing
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 heat range of spark plug
  • Improper octane value gasoline
Clank noise when engine speed is (1, 000 - 2, 000 r/min) Sound is reduced when the fuel injector of the noisy cylinder is stopped.(1)
  • Worn crankshaft bearing
  • Worn connecting rod bearing
Knocking sound when engine is operating under idling speed and engine is warm Sound is reduced when the fuel injector of the noisy cylinder is stopped.(1)
  • Worn cylinder liner and piston ring
  • Broken or stuck piston ring
  • Worn piston pin and piton pin hole of piston
Sound is not reduced if each fuel injector is stopped in turn.(1)
  • Unusually worn valve rocker
  • Unusually worn valve shim
  • Worn cam sprocket
  • Worn journal of cam carrier and camshaft cap
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 -
  • Defective V-belt tensioner assembly (loose V-belt)
  • Defective water pump shaft
Hissing sound -
  • Insufficient compression
  • Air leakage in air intake system, hose, connection or manifold
Timing chain noise -
  • Loose timing chain
  • Timing chain contacting with adjacent part
Valve noise -
  • Incorrect cam clearance
(1) Fuel injector can be stopped using the Subaru Select Monitor. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>ACTIVE TEST>OPERATION
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