Compression - Subaru Impreza 2002 Service Manual

MECHANICAL

2. Compression

A: INSPECTION
CAUTION:
After warming-up, engine becomes very hot. Be
careful not to burn yourself during measure-
ment.
1) After warming-up the engine, turn the ignition
switch to OFF.
2) Make sure that the battery is fully charged.
3) Release fuel pressure. <Ref. to FU(TURBO)-53,
RELEASING OF FUEL PRESSURE, OPERA-
TION, Fuel.>
4) Remove all the spark plugs. <Ref. to IG(TUR-
BO)-4, REMOVAL, Spark Plug.>
5) Fully open the throttle valve.
6) Check the starter motor for satisfactory perfor-
mance and operation.
7) Hold the compression gauge tight against the
spark plug hole.
CAUTION:
When using a screw-in type compression
gauge, the screw (put into cylinder head spark
plug hole) should be less than 18 mm (0.71 in)
long.
8) Crank the engine by means of the starter motor,
and read the maximum value on the gauge when
the pointer is steady.
9) Perform at least two measurements per cylinder,
and make sure that the values are correct.
Compression (350 rpm and fully open throttle):
Standard;
951 — 1,147 kPa (9.7 — 11.7 kg/cm
166 psi)
Limit;
883 kPa (9.0 kg/cm
Difference between cylinders;
49 kPa (0.5 kg/cm
COMPRESSION
EN0172
2
, 138 —
2
, 128 psi)
2
, 7 psi)
ME(STi)-22