Compression Check: Testing and Inspection
INSPECTIONHINT: If there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.
1. WARM UP ENGINE
Allow the engine to warm up to normal operating temperature.
2. REMOVE IGNITION COILS
3. REMOVE SPARK PLUGS
4. INSPECT CYLINDER COMPRESSION PRESSURE
a. Insert a compression gauge into the spark plug hole.
b. Fully open the throttle.
c. While cranking the engine, measure the compression pressure.
HINT: Always use a fully charged battery to obtain the engine speed of 250 rpm or more.
d. Repeat steps a. through c. for each cylinder.
NOTICE: This measurement must be done as short a time as possible.
Compression pressure
e. If the cylinder compression is low in one more cylinders, pour a small amount of engine oil into the cylinder through the spark plug hole and repeat steps a. through c. for cylinders with low compression.
- If adding oil helps the compression, it is likely that the piston rings and/or cylinder bore are worn or damaged.
- If the pressure stays low, a valve may be sticking or the seating is improper, or there may be leakage past the gasket.
5. REINSTALL SPARK PLUGS
6. REINSTALL IGNITION COILS