Compression Check: Testing and Inspection

COMPRESSION PRESSURE

Inspection

1.Warm up engine and then turn it off.
2.Release fuel pressure. Testing and Inspection.
3.Remove ignition coil and spark plug from each cylinder. Exploded View.
4.Connect engine tachometer (not required in use of CONSULT).





5.Install compression gauge (B) with an adapter (A) (commercial service tool) onto spark plug hole.





- Use an adapter with a diameter (a) smaller than 20 mm (0.79
in). Otherwise, it may be caught by cylinder head during removal.





6.With accelerator pedal fully depressed, turn ignition switch to START for cranking. When the gauge pointer stabilizes, read the compression pressure and the engine rpm. Perform these steps to check each cylinder.
Compression pressure: General Specifications.

CAUTION:
Always use a fully charged battery to obtain the specified engine speed.
- If the engine speed is out of the specified range, check the battery. Check the engine speed again with a fully charged battery.
- If some cylinders have low compression pressure, pour a small amount of engine oil into the spark plug hole to recheck the compression.
- If the added engine oil improves the compression, the piston rings may be worn or damaged. Check the piston rings and replace if necessary.
- If the compression pressure remains low despite the addition of engine oil, the valves may be malfunctioning. Check the valves for damage. Replace the valve or valve seat as necessary.
- If two adjacent cylinders have respectively low compression pressure and their compression remains low even after the addition of engine oil the head gasket may be leaking, or valves in adjacent cylinders may be damaged. Inspect and repair as required.
- If the compression pressure is below the minimum value, check the valve clearances and parts associated with the combustion chamber (valve, valve seat, piston, piston ring, cylinder bore, cylinder head, cylinder head gasket). After repairing, measure the compression pressure again.
7.After inspection is completed, install removed parts.
8.Start the engine, and ensure that the engine runs smoothly.
9.Perform trouble diagnosis. If DTC appears, erase it. Work Flow.