Subaru Legacy IV (2008 year). Manual - part 281

ME(H4DOTC)-104

Engine Trouble in General

MECHANICAL

5. Engine does not return to 
idle.

Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Loosened or cracked vacuum hose

A

Others

Stuck or damaged throttle valve

A

6. Dieseling (Run-on)

Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>

A

Cooling system

Over-heating

B

Others

Evaporative emission control system malfunction

B

7. After burning in exhaust 
system

Engine control system <Ref. to EN(H4DOTC)(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

Timing belt

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

Lubrication system

Incorrect oil pressure

C

Cooling system

Over-cooling

C

Others

Evaporative emission control system malfunction

C

8. Knocking

Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Loosened oil filler cap

B

Timing belt

Defective timing

B

Compression

Incorrect valve clearance

C

Incorrect valve timing

B

Cooling system

Over-heating

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 gasket

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

Symptoms

Problem parts etc.

Possible cause

RANK

ME(H4DOTC)-105

Engine Trouble in General

MECHANICAL

10. Excessive fuel consump-
tion

Engine control system <Ref. to EN(H4DOTC)(diag)-2, Basic Diagnostic Procedure.>

A

Intake system

Dirty air cleaner element

A

Timing belt

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

Lubrication system

Incorrect oil pressure

C

Cooling system

Over-cooling

C

Symptoms

Problem parts etc.

Possible cause

RANK

ME(H4DOTC)-106

Engine Noise

MECHANICAL

26.Engine Noise

A: INSPECTION

NOTE*)
When disconnecting the fuel injector connector, the malfunction indicator light illuminates and DTC is stored in ECM memory.
Therefore, perform the Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-52, OPERATION, Clear Memory Mode.> and Inspec-
tion Mode <Ref. to EN(H4DOTC)(diag)-43, PROCEDURE, Inspection Mode.> after connecting the 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 (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 of gasoline

Clank when engine speed is 
between 1,000 and 2,000 rpm.

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

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

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

Noise 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 sprocket
• Worn camshaft journal bore in cylinder head

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

 — 

• Loose V-belt
• Defective water pump shaft

Hissing sound

 — 

• Insufficient compression
• Air leakage in air intake system, hose, connection or manifold

Timing belt noise

 — 

• Loose timing belt
• Timing belt contacting with adjacent part

Valve noise

 — 

Incorrect valve clearance

EX(H4DOTC)-2

General Description

EXHAUST

1. General Description

A: COMPONENT

1. FRONT EXHAUST PIPE

(1)

Gasket

(11)

Gasket

Tightening torque:N·m (kgf-m, ft-lb)

(2)

Exhaust manifold RH upper cover

(12)

Exhaust manifold LH inner cover

T1: 19 (1.9, 14.0)

(3)

Exhaust manifold RH

(13)

Exhaust manifold LH outer cover

T2: 25 (2.5, 18.4)

(4)

Exhaust manifold RH lower cover

(14)

Gasket

T3: 40 (4.1, 29.5)

(5)

Front exhaust pipe upper cover

(15)

Turbocharger joint pipe

T4: 42.5 (4.3, 31.3)

(6)

Front exhaust pipe insulator RH

(16)

Gasket

T5: <Ref. to FU(H4DOTC)-46, 

INSTALLATION, Front Oxygen 
(A/F) Sensor.>

(7)

Gasket

(17)

Front oxygen (A/F) sensor

(8)

Front exhaust pipe

(18)

Exhaust manifold LH

(9)

Front exhaust pipe insulator LH

(19)

Ground cable

(10)

Front exhaust pipe lower cover

EX-02330

T1

T1

T4

T3

T4

T3

T1

T2

T1

(1)

(3)

(6)

(1)

(13)

(12)

(8)

(5)

(15)

(17)

(16)

(9)

(9)

(18)

(14)

(4)

(2)

A

A

(6)

(10)

T5

T2

T2

(7)

(11)

(19)

T4

T4

T4

T2