Subaru Legacy III (2000-2003 year). Manual - part 272

ME(H6DO)-76

MECHANICAL

ENGINE TROUBLE IN GENERAL

3. Low output, hesitation and 
poor acceleration

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

A

• Intake system

• Loosened or cracked intake duct

A

• Loosened or cracked PCV hose

A

• Loosened or cracked vacuum hose

B

• Defective intake manifold gasket

B

• Defective throttle body gasket

B

• Defective PCV valve

B

• Loosened oil filler cap

B

• Dirty air cleaner element

A

• Fuel line

• Defective fuel pump and relay

B

• Clogged fuel line

B

• Lack of or insufficient fuel

C

• Chain

• Defective timing

B

• Compression

• Incorrect valve clearance

B

• Loosened spark plugs or defective gasket

B

• Loosened cylinder head bolts or defective gasket

B

• Improper valve seating

B

• Defective valve stem

C

• Worn or broken valve spring

B

• Worn or stuck piston rings, cylinder and piston

C

• Incorrect valve timing

A

• Improper engine oil (low viscosity)

B

• Lubrication system

• Incorrect oil pressure

B

• Cooling system

• Overheating

C

• Over cooling

C

• Others

• Malfunction of evaporative emission control system

A

4. Surging

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

A

• Intake system

• Loosened or cracked intake duct

A

• Loosened or cracked PCV hose

A

• Loosened or cracked vacuum hose

A

• Defective intake manifold gasket

B

• Defective throttle body gasket

B

• Defective PCV valve

B

• Loosened oil filler cap

B

• Dirty air cleaner element

B

• Fuel line

• Defective fuel pump and relay

B

• Clogged fuel line

B

• Lack of or insufficient fuel

C

• Chain

• Defective timing

B

• Compression

• Incorrect valve clearance

B

• Loosened spark plugs or defective gasket

C

• Loosened cylinder head bolts or defective gasket

C

• Improper valve seating

C

• Defective valve stem

C

• Worn or broken valve spring

C

• Worn or stuck piston rings, cylinder and piston

C

• Incorrect valve timing

A

• Improper engine oil (low viscosity)

B

• Cooling system

• Overheating

B

• Others

• Malfunction of evaporative emission control system

C

TROUBLE

PROBLEM PARTS, ETC.

POSSIBLE CAUSE

RANK

ME(H6DO)-77

MECHANICAL

ENGINE TROUBLE IN GENERAL

5. Engine does not return to 
idle.

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

A

• Intake system

• Loosened or cracked vacuum hose

A

• Others

• Stuck or damaged throttle valve

A

• Accelerator cable out of adjustment

B

6. Dieseling (Run-on)

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

A

• Cooling system

• Overheating

B

• Others

• Malfunction of evaporative emission control system

B

7. After burning in exhaust 
system

• Engine control system <Ref. to EN(H6DO)-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 plugs or defective gasket

C

• Loosened cylinder head bolts or defective gasket

C

• Improper valve seating

B

• Defective valve stem

C

• Worn or broken valve spring

C

• Worn or stuck piston rings, cylinder and piston

C

• Incorrect valve timing

A

• Lubrication system

• Incorrect oil pressure

C

• Cooling system

• Over cooling

C

• Others

• Malfunction of evaporative emission control system

C

8. Knocking

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

A

• Intake system

• Loosened oil filter cap

B

• Chain

• Defective timing

B

• Compression

• Incorrect valve clearance

C

• Incorrect valve timing

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 
gasket

B

• Defective oil filter seal

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

TROUBLE

PROBLEM PARTS, ETC.

POSSIBLE CAUSE

RANK

ME(H6DO)-78

MECHANICAL

ENGINE TROUBLE IN GENERAL

10. Excessive fuel consump-
tion

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

A

• Intake system

• Dirty air cleaner element

A

• Chain

• Defective timing

B

• Compression

• Incorrect valve clearance

B

• Loosened spark plugs or defective gasket

C

• Loosened cylinder head bolts or defective gasket

C

• Improper valve seating

B

• Defective valve stem

C

• Worn or broken valve spring

C

• Worn or stuck piston rings, cylinder and piston

B

• Incorrect valve timing

B

• Lubrication system

• Incorrect oil pressure

C

• Cooling system

• Over cooling

C

• Others

• Accelerator cable out of adjustment

B

TROUBLE

PROBLEM PARTS, ETC.

POSSIBLE CAUSE

RANK

ME(H6DO)-79

MECHANICAL

ENGINE NOISE

20.Engine Noise

A: INSPECTION

NOTE*:
When disconnecting fuel injector connector, Malfunction Indicator Light (CHECK ENGINE light) illuminates and trouble code is
stored in ECM memory.
Therefore, carry out the CLEAR MEMORY MODE <Ref. to EN(H6DO)-54, Clear Memory Mode.> and INSPECTION MODE
<Ref. to EN(H6DO)-47, Inspection Mode.> after connecting fuel injector connector.

Type of sound

Condition

Possible cause

Regular clicking sound

Sound increases as engine 
speed increases.

• Valve mechanism is defective.
• Incorrect valve clearance
• Worn camshaft
• Broken valve spring

Heavy and dull clank

Oil pressure is low.

• Worn crankshaft main bearing
• Worn connecting rod bearing (big end)

Oil pressure is normal.

• Loose flywheel mounting bolts
• Damaged engine mounting

High-pitched clank (Spark 
knock)

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 
medium (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

— 

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

Timing chain noise

— 

• Loose timing chain
• Chain contacting case/adjacent part

Valve tappet noise

— 

• Incorrect valve clearance