Compression - Subaru 2004 Impreza 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) Lower the fuel pressure. <Ref. to FU(H4SO)-50,
RELEASING OF FUEL PRESSURE, OPERA-
TION, Fuel.> or <Ref. to FU(H4SOw/oOBD)-46,
RELEASING OF FUEL PRESSURE, OPERA-
TION, Fuel.>
4) Remove all the spark plugs. <Ref. to IG(H4SO)-
5, 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 spark
plug hole.
NOTE:
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 starter motor, and
then 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;
1,275 kPa (13.0 kgf/cm
Limit;
1,020 kPa (10.4 kgf/cm
Difference between cylinders;
49 kPa (0.5 kgf/cm
Compression
ME-00192
2
, 185 psi)
2
, 148 psi)
2
, 7 psi), or less
ME(H4SO)-26