Compression Test
- Ensure engine oil level is correct. Ensure battery is fully charged and starter is operating correctly.
- Start engine. Bring engine to normal operating temperature.
- Stop engine. Remove spark plugs.
- Insert compression gauge into first cylinder. Depress accelerator pedal to ensure throttle is fully open. Crank engine and read gauge.
- Repeat for all cylinders, making sure pressure difference for each of the cylinders is within specified limit. See COMPRESSION SPECIFICATIONS table.
- If a cylinder's compression reading or pressure differential is outside specification, add a small amount of oil to that cylinder. Repeat compression test on that cylinder.
- If the addition of oil causes compression to rise, check for worn piston rings. If the addition of oil does not increase compression, check for valve seating or head gasket problems.