Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual - part 73
ME(STI)-54
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-04717