Subaru Legacy IV (2008 year). Manual - part 506

IG(H6DO)-5

Spark Plug

IGNITION

6) Remove the spark plug with a spark plug socket.

B: INSTALLATION

1. RH SIDE

Install in the reverse order of removal.

Tightening torque (Spark plug):

21 N·m (2.1 kgf-m, 15.5 ft-lb)

Tightening torque (Ignition coil):

16 N·m (1.6 kgf-m, 11.8 ft-lb)

2. LH SIDE

Install in the reverse order of removal.

Tightening torque (Spark plug):

21 N·m (2.1 kgf-m, 15.5 ft-lb)

Tightening torque (Ignition coil):

16 N·m (1.6 kgf-m, 11.8 ft-lb)

C: INSPECTION

Check the electrodes and inner and outer ceramic
insulator of plugs, noting the type of deposits and
the degree of electrode erosion.

1) Normal:
Brown to grayish-tan deposits and slight electrode
wear indicate correct spark plug heat range.

2) Carbon fouled:
Dry fluffy carbon deposits on insulator and elec-
trode are mostly caused by slow speed driving in
the city, weak ignition, too rich fuel mixture and dirty
air cleaner.

(A) Ratchet handle

(B) Extension bar

(C) Universal joint

(D) Spark plug socket

IG-02007

(D)

(C)

(B)

(B)

(A)

IG-02011

(A) Spark plug gap

(B) Carbon accumulation or wear

(C) Crack

(D) Damage

(E) Damaged gasket

IG-00010

(A)

(B)

(C)

(D)

(E)

IG-00011

IG-00012

IG(H6DO)-6

Spark Plug

IGNITION

3) Oil fouled:
Wet black deposits show oil entrance into the com-
bustion chamber through worn rings and excessive
clearance between valve guides and stems.

4) Overheating:
White or light gray insulator with black or brown
spots and bluish burnt electrodes indicate engine
overheating, incorrect ignition timing, wrong selec-
tion of fuel, and loose spark plugs.

D: ADJUSTMENT

Clean spark plugs with a nylon brush, etc. Clean
and remove the carbon or oxide deposits. If depos-
its are too stubborn, replace the spark plugs.
After cleaning the spark plugs, measure the spark
plug gap using a gap gauge.

NOTE:
• Never use a plug cleaner.
• Never use a metal brush because it makes insu-
lator worn.

Spark plug gap L:

0.7 — 0.8 mm (0.028 — 0.031 in)

IG-00013

IG-00014

IG-02035

L

IG(H6DO)-7

Ignition Coil

IGNITION

3. Ignition Coil

A: REMOVAL

Direct ignition type has been adopted. Refer to
“Spark Plug” for removal procedure. <Ref. to
IG(H6DO)-4, REMOVAL, Spark Plug.>

B: INSTALLATION

Install in the reverse order of removal.

Tightening torque:

16 N·m (1.6 kgf-m, 11.8 ft-lb)

C: INSPECTION

For inspection procedure, refer to “Diagnostics for
Engine Starting Failure”. <Ref. to EN(H6DO)(diag)-
73, IGNITION CONTROL SYSTEM, Diagnostics
for Engine Starting Failure.>

IG(H6DO)-8

Ignition Coil

IGNITION