Compression Check: Testing and Inspection

COMPRESSION
Inspection
1. Verify that the battery is fully charged. Recharge it if necessary.
2. Warm up the engine to the normal operating temperature.
3. Stop the engine and allow it to cool for about 10 minutes.
4. Remove the spark plugs.
5. Install the SST into the No.1 spark plug hole.
6. Fully depress the accelerator pedal and crank the engine.
7. Note the maximum gauge reading.
8. Check each cylinder as above.
Compression






9. It the compression in one or more cylinders is low, pour a small amount of clean engine oil into the cylinder and recheck the compression.
(1) It the compression increases, the piston, piston rings, or cylinder wall may be worn.
(2) It the compression stays low, a valve may be stuck or improperly seated.
(3) If the compression in adjacent cylinders stays low, the cylinder head gasket may be damaged or the cylinder head distorted.
10. Remove the SST.
11. Install the spark plugs.