Compression Check: Testing and Inspection

COMPRESSION
If the engine exhibits low power, poor fuel economy, or poor idle, check the following:
1. Ignition system
2. Compression
3. Fuel system

INSPECTION
1. Check that the battery if fully charged. Recharge it if necessary.
2. Warm up the engine to normal operating temperature.
3. Remove the center cover.
4. Disconnect the high tension lead and ignition coil.
5. Remove all spark plugs.





6. Connect a compression gauge to the No.1 spark plug hole.
7. Fully depress the accelerator pedal and crank the engine.
8. Record the maximum gauge reading.





9. Check each cylinder.
10. If the compression in one or more cylinders is low, pour a small amount of engine oil into the cylinder and recheck the compression.
1) If the compression increases, the piston, piston rings, or cylinder wall may be worn.
2) If the compression stays low, the valve may be stuck or seating improperly.
3) If the compression in adjacent cylinders stays low, the cylinder head gasket may be defective or the cylinder head distorted.