Section 4 (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.
NOTE: Follow the steps below when removing the collector cover.
1. Pull up the two points at the rear (A).
2. Pull up the two points at the front (B) while moving them forward.
  
  Fig 1: Removing Collector Cover
  Courtesy of SUBARU OF AMERICA, INC.
After warming-up the engine, turn the ignition switch to OFF.
Make sure that the battery is fully charged.
Remove the fuse of fuel pump from main fuse box.

Fig 2: Locating Fuel Pump Fuse On Main Fuse Box
Courtesy of SUBARU OF AMERICA, INC.
Start the engine and run it until it stalls.
After the engine stalls, crank it for five more seconds.
Turn the ignition switch to OFF.
Remove all spark plugs. Refer to REMOVAL .
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 the starter motor, and read the maximum value on the gauge when the needle of gauge is steady.
NOTE:
- Perform at least two measurements per cylinder, and make sure that the values are correct.
- If the compression pressure is out of standard, check or adjust the pistons, valves and cylinders.
Compression (350 rpm and fully open throttle):

Standard

1, 275 - 1, 471 kPa (13.0 - 15.0 kgf/cm ² , 185 - 213 psi)

Limit

1, 128 kPa (11.5 kgf/cm ² , 164 psi)

Difference between cylinders

49 kPa (0.5 kgf/cm ² , 7 psi) or less
After inspection, install the related parts in the reverse order of removal.