Compression Check: Testing and Inspection

CHECKING COMPRESSION PRESSURE
1. Before checking compression, check the engine oil level. Make sure the starter motor and battery are in normal operating condition.

NOTE: Always use a fully-charged battery to obtain specified engine revolution.

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]: 14.5 kg/cm2 (1.47 Mpa, 213 psi)
Limit: 13 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 engine 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.
3) If compression in any two adjacent cylinder is low and if adding oil does not help compression, there is leakage past the gasket surface. If so, replace cylinder head gasket.
Tightening torque
Spark plug: 20-30 Nm (200-300 kgf-cm, 15-21 ft. lbs.)