Subaru Legacy (2005 year). Manual - part 404

ME(H6DO)-91

MECHANICAL

Engine Trouble in General

7. After burning in exhaust 
system

Engine control system <Ref. to EN(H6DO)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Loosened or cracked intake duct

C

Loosened or cracked PCV hose

C

Loosened or cracked vacuum hose

B

Defective PCV valve

B

Loosened oil filler cap

C

Chain

Defective timing

B

Compression

Incorrect valve clearance

B

Loosened spark plug or defective gasket

C

Loosened cylinder head bolt or defective gasket

C

Improper valve sealing

B

Defective valve stem

C

Worn or broken valve spring

C

Worn or stuck piston rings, cylinder and piston

C

Incorrect valve timing

A

Trouble of tappet

C

Trouble of tappet. In case noise occurs with valve mov-
ing. Or the harness involved to oil switching solenoid 
valve, variable valve lift diagnosis oil pressure switch 
and variable valve lift has trouble in a past.

B

Lubrication system

Incorrect oil pressure

C

Cooling system

Over-cooling

C

Other

Evaporative emission control system malfunction

C

8. Knocking

Engine control system <Ref. to EN(H6DO)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Loosened oil filler cap

B

Chain

Defective timing

B

Compression

Incorrect valve clearance

C

Incorrect valve timing

B

Trouble of tappet

C

Trouble of tappet. In case noise occurs with valve mov-
ing. Or the harness involved to oil switching solenoid 
valve, variable valve lift diagnosis oil pressure switch 
and variable valve lift has trouble in a past.

B

Cooling system

Overheating

A

9. Excessive engine oil con-
sumption

Intake system

Loosened or cracked PCV hose

A

Defective PCV valve

B

Loosened oil filler cap

C

Compression

Defective valve stem

A

Worn or stuck piston rings, cylinder and piston

A

Lubrication system

Loosened oil pump attaching bolts and defective gas-
ket

B

Defective oil filter o-ring

B

Defective crankshaft oil seal

B

Defective rocker cover gasket

B

Loosened oil drain plug or defective gasket

B

Loosened oil pan fitting bolts or defective oil pan

B

Symptom

Problem parts, etc.

Possible cause

Rank

ME(H6DO)-92

MECHANICAL

Engine Trouble in General

10. Excessive fuel consump-
tion

Engine control system <Ref. to EN(H6DO)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Dirty air cleaner element

A

Chain

Defective timing

B

Compression

Incorrect valve clearance

B

Loosened spark plug or defective gasket

C

Loosened cylinder head bolt or defective gasket

C

Improper valve sealing

B

Defective valve stem

C

Worn or broken valve spring

C

Worn or stuck piston rings, cylinder and piston

B

Incorrect valve timing

B

Trouble of tappet

C

Trouble of tappet. In case noise occurs with valve mov-
ing. Or the harness involved to oil switching solenoid 
valve, variable valve lift diagnosis oil pressure switch 
and variable valve lift has trouble in a past.

B

Lubrication system

Incorrect oil pressure

C

Cooling system

Over-cooling

C

Symptom

Problem parts, etc.

Possible cause

Rank

ME(H6DO)-93

MECHANICAL

Engine Noise

30.Engine Noise 

A: INSPECTION

NOTE*)
When disconnecting the fuel injector connector, the malfunction indicator light illuminates and DTC is stored in ECM memory.
Therefore, carry out the clear memory mode <Ref. to EN(H6DO)(diag)-41, OPERATION, Clear Memory Mode.> and inspection
mode <Ref. to EN(H6DO)(diag)-34, PROCEDURE, Inspection Mode.> after connecting the fuel injector connector.

Type of sound

Condition

Possible cause

Regular clicking sound

Sound increases as engine 
speed increases.

• Defective valve mechanism
• Incorrect valve clearance
• Worn valve rocker
• Worn camshaft
• Broken valve spring
• Trouble of tappet

Heavy and dull clank

Oil pressure is low.

• Worn camshaft main bearing
• Worn connecting rod bearing (large end)

Oil pressure is normal.

Damaged engine mounting

High-pitched clank

Sound is noticeable when 
accelerating with an overload.

• Ignition timing advanced
• Accumulation of carbon inside combustion chamber
• Wrong spark plug
• Improper gasoline

Clank when engine speed is 
1,000 to 2,000 rpm

Sound is reduced when fuel 
injector connector of noisy cyl-
inder is disconnected. 
(NOTE*)

• Worn crankshaft main bearing
• Worn bearing at crankshaft end of connecting rod

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*)

• Worn cylinder liner and piston ring
• Broken or stuck piston ring
• Worn piston pin and hole at piston end of connecting rod

Sound is not reduced if each 
fuel injector connector is dis-
connected in turn. (NOTE*)

• Unusually worn valve lifter
• Worn cam gear
• Worn camshaft journal bore in crankcase

Squeaky sound

—

• Insufficient generator lubrication

Rubbing sound

—

• Defective generator brush and rotor contact

Gear scream when starting 
engine

—

• Defective ignition starter switch
• Worn gear and starter pinion

Sound like polishing glass with 
a dry cloth

—

• Loose drive belt
• Defective water pump shaft

Hissing sound

—

• Insufficient compression
• Air leakage in air intake system, hoses, connections or mani-
folds

Timing belt noise

—

• Loose timing belt
• Belt contacting with case/adjacent part

Valve tappet noise

—

• Incorrect valve clearance
• Trouble of tappet

ME(H6DO)-94

MECHANICAL

Engine Noise