Compression Check: Testing and Inspection
Measurement of Compression Pressure1. Warm up engine.
2. Turn ignition switch OFF.
3. Release fuel pressure. Refer to Powertrain Management; Fuel Delivery and Air Induction.
4. Remove all spark plugs.
5. Disconnect distributor coil connector.
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.
^ Always use a fully-charged battery to obtain specified engine speed.
Compression pressure: kPa (kg/cm2, psi)/rpm
Standard 1,275 (13.0, 185)/300
Minimum 1,079 (11.0, 156)/300
Difference limit between cylinders 98 (1.0, 14)/300
10. If compression in one or more cylinders is low:
a. Pour a small amount of engine oil into cylinders through spark plug holes.
b. 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. If valve or valve seat is damaged excessively, replace them. Refer to Valve Seat; Specifications.
^ If compression stays low in two cylinders that are next to each other:
a. The cylinder head gasket may be leaking, or
b. Both cylinders may have valve component damage. Inspect and repair as necessary.