Engine Noise: Inspection

WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

POSSIBLE CAUSE REFERENCE CHART

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 and connecting rod cap bearing at connecting rod large end

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 when engine speed is between 1, 000 and 2, 000 rpms.

Sound is reduced when the fuel injector connector of the noisy cylinder is disconnected.⁽¹⁾

Worn crankshaft bearing
Worn connecting rod bearing and connecting rod cap bearing at connecting rod large end

Knocking sound when engine is operating under idling speed and engine is warm

Sound is reduced when the fuel injector connector of the 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 camshaft 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 automatic belt tensioner adjuster 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, perform the Clear Memory Mode < refer to OPERATION , Clear Memory Mode > and Inspection Mode < refer to PROCEDURE , Inspection Mode > after connecting the fuel injector connector.