Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 167

ME(w/o STI)-49

Timing Belt

MECHANICAL

(2) Using white paint, put an alignment mark or

an arrow mark on timing belts in relation to the

crank sprocket and cam sprockets.

Z

1

: 54.5 teeth

Z

2

: 51 teeth

Z

3

: 28 teeth

5) Remove the belt idler (A).

6) Remove the timing belt.
CAUTION:

After the timing belt has been removed, never

rotate the intake and exhaust sprocket. If the

cam sprocket is rotated, the intake and exhaust

valve heads strike together and valve stems are

bent.

2. AUTOMATIC BELT TENSION ADJUST-

ER ASSEMBLY AND BELT IDLER

1) Remove the belt idler (A) and (B).

2) Remove the belt idler No. 2.

3) Remove the automatic belt tension adjuster as-

sembly.

ME-00070

ME-03175

ME-03176

Z

3

Z

1

Z

2

Z

3

(A)

ME-03935

(A)

(B)

ME-03936

ME-04977

ME-04978

ME(w/o STI)-50

Timing Belt

MECHANICAL

B: INSTALLATION

1. AUTOMATIC BELT TENSION ADJUST-

ER ASSEMBLY AND BELT IDLER

1) Prepare for installation of the automatic belt ten-

sion adjuster assembly.
CAUTION:

• Always use a vertical type pressing tool to

move the adjuster rod down.

• Do not use a lateral type vise.

• Push the adjuster rod vertically.

• Press-in the push adjuster rod gradually tak-

ing three minutes or more.

• Do not allow press pressure to exceed 9,807

N (1,000 kgf, 2,205 lb).

• Push in the adjuster rod to the end face of the

cylinder. However, do not press the adjuster

rod below the end face of the cylinder. Doing so

may damage the cylinder.

• Do not release the press pressure until stop-

per pin is completely inserted.

(1) Attach the automatic belt tension adjuster

assembly to vertical pressing tool.

(2) Slowly push in the adjuster rod with a pres-

sure of 165 N (16.8 kgf, 37.1 lbf) or more until

the adjuster rod is aligned with the stopper pin

hole in the cylinder.

(3) With a 2 mm (0.08 in) dia. stopper pin or a 2

mm (nominal) dia. hex wrench inserted into the

stopper pin hole in cylinder, secure the adjuster

rod.

2) Install the automatic belt tension adjuster as-

sembly.
Tightening torque:

39 N·m (4.0 kgf-m, 28.8 ft-lb)

3) Install the belt idler No. 2.
Tightening torque:

39 N·m (4.0 kgf-m, 28.8 ft-lb)

4) Install the belt idlers.
Tightening torque:

39 N·m (4.0 kgf-m, 28.8 ft-lb)

ME-00239

ME-00350

ME-04979

ME-04977

ME-04980

ME(w/o STI)-51

Timing Belt

MECHANICAL

Tightening torque:

25 N·m (2.5 kgf-m, 18.4 ft-lb)

2. TIMING BELT

1) Prepare for installation of the automatic belt ten-

sion adjuster assembly. <Ref. to ME(w/o STI)-50,

AUTOMATIC BELT TENSION ADJUSTER AS-

SEMBLY AND BELT IDLER, INSTALLATION,

Timing Belt.>

2) Align the mark (B) on crank sprocket with the

mark (A) on oil pump.

3) Align the single line mark (B) on the exhaust cam

sprocket RH with notch (A) on the timing belt cover.

4) Align the single line mark (B) on the intake cam

sprocket RH with notch (A) on the timing belt cover.

Make sure that the double line marks (C) on intake

cam sprocket and exhaust cam sprocket are

aligned.

5) Align the single line mark (B) on exhaust cam

sprocket LH with notch (A) on the timing belt cover

by turning the sprocket counterclockwise (as

viewed from front of engine).

6) Align the single line mark (B) on intake cam

sprocket LH with notch (A) on the timing belt cover

by turning the sprocket clockwise (as viewed from

front of engine). Make sure that the double line

marks (C) on intake cam sprocket and exhaust cam

sprocket are aligned.

ME-04981

(B)

ME-04082

(A)

ME-04088

(A)

(B)

ME-04084

(A)

(C)

(B)

ME-04089

(B)

(A)

ME-04086

(B)

(A)

(C)

ME(w/o STI)-52

Timing Belt

MECHANICAL

7) Make sure that the cam and crank sprockets are

positioned properly.
CAUTION:

• Intake and exhaust camshafts for this DOHC

engine can be independently rotated with the

timing belts removed. As can be seen from the

figure, if the intake and exhaust valves are lifted

simultaneously, heads will interfere with each

other, resulting in bent valves.

• When the timing belts are not installed, four

camshafts are held at the “zero-lift” position,

where all cams on camshafts are not pushing

down on the intake and exhaust valves. (Under

this condition, all valves remain unlifted.)

• When the camshafts are rotated to install the

timing belts, #2 intake and #4 exhaust cam of

camshaft LH are held, pushing their corre-

sponding valves down. (Under this condition,

these valves are held lifted.) Camshaft RH are

held so that their cams do not push the valves

down.

• Camshafts LH must be rotated from the zero-

lift position to the position where the timing belt

is to be installed with the smallest possible an-

gle, in order to prevent mutual interference of

intake and exhaust valve heads.

• Do not allow the camshafts to rotate in the di-

rection shown in the upper figure. Doing this

may cause both the intake and exhaust valves

to lift simultaneously, resulting in mutual inter-

ference of valve heads.

(A) Intake camshaft
(B) Exhaust camshaft

ME-04111

(A)

(B)

(A) Direction of rotation
(B) Timing belt installation position

(A)

(A)

(A)

(A)

(B)

(B)

ME-04680