Section 13 (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.

Remove the collector cover.
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.
Fully open the throttle valve.
Check the starter motor for satisfactory performance and operation.
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.
Crank the engine by means of the starter motor, and read the maximum value on the gauge when the pointer is steady.

Fig 1: Checking Compression
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)
After inspection, install the related parts in the reverse order of removal.