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Home >> Subaru >> 2017 >> Forester 2.0XT Touring >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 6 (Engine Mechanical (H4DO)) >> Engine Noise >> Inspection

Engine Noise: Inspection

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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) Noise is reduced when fuel injector connector of noisy cylinder is disconnected.(1)
  • Worn crankshaft bearing
  • Worn connecting rod bearing
Knocking sound when engine is operating under idling speed and engine is warm Noise is reduced when fuel injector connector of noisy cylinder is disconnected.(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 connector is disconnected 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) When disconnecting the fuel injector connector, the malfunction indicator light illuminates and DTC is stored in ECM memory.

Therefore, after connecting the fuel injector connector, execute Clear Memory Mode Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Clear Memory Mode>OPERATION . and Inspection Mode Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Inspection Mode>PROCEDURE .

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