Compression Check: Testing and Inspection
CHECKING COMPRESSION PRESSURE1. Before checking compression, check the engine oil level. Make sure the starter motor and battery are in normal operating condition.
2. Start the engine and wait until engine coolant temperature reaches 80 - 95°C (176 - 205°F).
3. Stop the engine and disconnect the spark plug cables.
4. Remove the spark plugs.
5. Crank the engine to remove any foreign objects in the cylinders.
6. Screw the compression gauge into the spark plug hole.
7. Fully open the throttle.
8. Crank the engine and read the gauge.
Standard value [at 250 - 400 rpm]: 15 kg/cm2 (1.47 MPa, 213 psi)
Limit 14 kg/cm2 (1.37 MPa, 199 psi)
9. Repeat steps 6 through 8 on all cylinders, making sure that the pressure differential for each of the cylinders is within the specified limit.
Limit: Max. 1.0 kg/cm2 (100 kPa,14 psi) between cylinders
10. If a cylinder's compression or pressure differential is below the specification, add a small amount of oil through the spark plug hole and repeat steps 6 through 9.
1. If the addition of oil brings the compression up, it is possible that there is wear between the piston ring and cylinder wall.
2. If compression remains the same, valve seizure, poor valve seating or a compression leak from the cylinder head gasket are all possible causes.
Tightening torque
Spark plug 20 - 30 Nm (200 - 300 kg.cm, 15 - 22 ft. lbs.)