2. The engine must be warmed up to normal operating temperature, the battery must be fully charged. All spark plugs must be removed (see chapter 1). In addition, you will need an assistant for this work.
3. Remove the fuel pump fuse (located in the fuse box in the passenger compartment), and, if possible, run the engine to burn off any remaining fuel in the system. Failure to do so may damage the catalytic converter.
4. Install the compression gauge into the spark plug hole of the 1st cylinder. A compression gauge that screws into the threaded spark plug hole is preferable.
5. Ask an assistant to fully depress the accelerator pedal and turn on the starter. After one or two crankshaft revolutions, the pressure in the cylinder should increase to the maximum, after which its value will stabilize. Record the maximum reading on the device.
6. Repeat the test in all other cylinders and record the pressure values in each of them.
7. The pressure readings in different cylinders should be close in value. The maximum difference in values between any two cylinders should not exceed 2 bar. Keep in mind that in a serviceable engine, the pressure should increase quickly. Low pressure on the first stroke followed by a gradual increase in subsequent strokes indicates wear of the piston rings. If the pressure is low after the first stroke and does not increase in subsequent strokes, this indicates leaks through the valves or through the cylinder head gasket (the reason for this may also be damage to the cylinder head itself). The presence of deposits on the undersides of the valve heads can also cause low pressure.
8. Recommended compression pressure values are given in Technical data.
9. If there is low pressure in one of the cylinders, perform an additional check to determine the cause. Pour some clean oil into such a cylinder through the spark plug hole (about a teaspoon) and check again.
10. If the pressure temporarily increases when adding oil, this indicates excessive wear of the cylinder or piston. If the pressure does not increase, this means that the cause may be leaks through burnt valves or through the cylinder head gasket.
11. Low pressure in two adjacent cylinders almost certainly indicates a leak through the gasket in the area between them. The presence of coolant in the engine oil confirms this assumption.
12. Reduced pressure in one of the cylinders by approximately 20% relative to other cylinders, as well as not entirely smooth engine operation at idle speed can be caused by wear of the camshaft cam.
13. If the pressure is unusually high, the cause may be carbon deposits in the combustion chamber. In this case, the cylinder head must be removed and cleaned.
14. To complete the check, screw in the spark plugs (see chapter 1) and insert the fuel pump fuse.