Compression Measurement

Measurement of Compression Pressure





1. Warm up engine.
2. Turn ignition switch off.
3. Disconnect fusible link for injectors.
4. Remove all spark plugs.
5. Disconnect distributor center cable.





6. Attach a compression tester to No. 1 cylinder.
7. Depress accelerator pedal fully to keep throttle valve wide open.
8. Crank engine and record highest gauge indication.
9. Repeat the measurement on each cylinder as shown above.
^ Always use a fully-charged battery to obtain specified engine revolution.

Compression pressure:
kPa (kg/sq.cm, psi)/rpm
Standard
1,206 (12.3, 175)/250
Minimum
1,010 (10.3, 146)/250
Difference limit between cylinders
98 (1.0, 14)/250

10. If cylinder compression in one or more cylinders is low, pour a small amount of engine oil into cylinders through spark plug holes and retest compression.
^ If adding oil helps compression, piston rings may be worn or damaged. If so, replace piston rings after checking piston.
^ If pressure stays low, a valve may be sticking or seating improperly. Inspect and repair valve and valve seat. (Refer to S.D.S.) If valve or valve seat Is damaged excessively, replace them.
^ If compression In any two adjacent cylinders is low and If adding oil does not help compression, there is leakage past the gasket surface. If so, replace cylinder head gasket.