Impreza WRX F4-2.0L DOHC Turbo (2004)
1) Measure the bend, and repair or replace if necessary.
Limit: 0.020 mm (0.0008 inch)
2) Check the journal for damage and wear. Replace if faulty.
3) Measure the outside diameter of camshaft journal. If the journal diameter is not as specified, check the oil clearance.
4) Measurement of the camshaft journal oil clearance:
a) Clean the bearing caps and camshaft journals.
b) Place the camshafts on the cylinder head. (Without installing the valve rocker.)
3) Place a plastigauge across each of the camshaft journals.
d) Gradually tighten the cap in at least two stages in alphabetical sequence shown in the figure, and then tighten to specified torque.
Tightening torque:
T1: 10 Nm (1.0 kgf-m, 7.2 ft. lbs.)
T2: 20 Nm (2.0 kgf-m, 14.5 ft. lbs.)
CAUTION: Do not turn the camshaft.
e) Remove the bearing caps.
f) Measure the widest point of the plastigauge on each journal. If the oil clearance exceeds the limit, replace the camshaft. If necessary, replace
the camshaft caps and cylinder head as a set.
Standard: 0.037 - 0.072 mm (0.0015 - 0.0028 inch)
Limit: 0.10 mm (0.0039 inch)
g) Completely remove the plastigauge.
