Section 23 (Engine Mechanical (H6DO)): Compression: Inspection

WARNING: This page is about a different variant/trim than selected.

CAUTION: After warming-up, engine becomes very hot. Be careful not to burn yourself during measurement.

After warming-up the engine, turn the ignition switch to OFF.
Make sure that the battery is fully charged.
Release the fuel pressure. < Refer to RELEASING OF FUEL PRESSURE , PROCEDURE, Fuel . >
Remove all the spark plugs. < Refer to REMOVAL , Spark Plug . >
Check the starter motor for satisfactory performance and operation.
Hold 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.
Fully open the throttle valve.
Crank the engine by means of the starter motor, and read the maximum value on the gauge when the pointer is steady.

Fig 1: Identifying Compression Gauge
Courtesy of SUBARU OF AMERICA, INC.
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 - 1,471 kPa (13.0 - 15.0 kgf/cm ² , 185 - 213 psi)

Service limit:

1,128 kPa (11.5 kgf/cm ² , 164 psi)