Subaru 2009 IMPREZA Service Manual page 240

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) Remove the fuse of fuel pump from main fuse
box.
4) Start the engine and run it until it stalls.
5) After the engine stalls, crank it for five more sec-
onds.
6) Turn the ignition switch to OFF.
7) Remove all spark plugs. <Ref. to IG(H4SO)-4,
REMOVAL, Spark Plug.>
8) Fully open the throttle valve.
9) Check the starter motor for satisfactory perfor-
mance and operation.
10) Secure the compression gauge tightly against
the spark plug hole.
NOTE:
When using a screw-in type compression gauge,
the screw should be less than 18 mm (0.71 in) long.
11) Crank the engine by the starter motor, and read
the maximum value on the gauge when the needle
of compression gauge is steady.
Compression
12) Perform at least two measurements per cylin-
der, and make sure that the values are correct.
Compression (fully open throttle):
Standard
1,020 — 1,275 kPa
(10.4 — 13.0 kgf/cm
Difference between cylinders
49 kPa (0.5 kgf/cm
13) After inspection, install the related parts in the
reverse order of removal.
FU-01122
ME-00192
ME(H4SO)-22
2
, 148 — 185 psi)
2
, 7 psi) or less