Subaru Legacy IV (2008 year). Manual - part 294
IG(H4DOTC)-5
Spark Plug
IGNITION
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)
Tightening torque (Air duct):
9 N·m (0.9 kgf-m, 6.6 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.
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.
(A) Spark plug gap
(B) Carbon accumulation or wear
(C) Crack
(D) Damage
(E) Damaged gasket
IG-02010
(A)
(B)
(E)
(C)
(D)
IG-00011
IG-00012
IG-00013
IG-00014