2. The engine must be warmed up to operating temperature, the battery must be fully charged and the spark plugs removed. Besides. You will need the help of an assistant.
3. Turn off; ignition system by disconnecting the high voltage wiring from the distributor cap and grounding it to the cylinder block. Use a jumper wire to make a good connection.
4. Install a compression gauge in the #1 spark plug hole.
5. Ask an assistant to hold the gas pedal fully depressed, and then turn the engine over with the starter. After one or two revolutions, the compression should increase to the maximum value and stabilize. Record the highest reading.
6. Repeat the test on the remaining cylinders. Make sure that the gas pedal remains fully depressed.
7. All cylinders should have an approximately equal pressure of about 11-15 bar. If the compression in any cylinder is less than 10 bar, or the difference between any two cylinders is greater than 1.5 bar, this indicates a malfunction. Please note that compression in a good engine increases rapidly: low compression on the first revolution and its subsequent gradual increase indicates worn piston rings. If compression remains low, the valves or cylinder head gasket are burnt, or the head is cracked. Carbon buildup on the backs of the valve heads can also be the cause of low compression.
8. If the pressure in one of the cylinders is low, pour a teaspoon of clean engine oil into it through the spark plug hole and repeat the test.
9. If after that the compression temporarily increases, the cylinder or piston is worn out. Lack of improvement indicates that there may be a leak through burnt valves or a burnt cylinder head gasket.
10. Low compression in two adjacent cylinders is almost certainly the cause. that the cylinder head gasket burned between them. The presence of coolant in the engine oil will confirm this.
11. If the compression in one of the cylinders is approximately 20% lower than in the others and the engine runs unevenly at idle, the camshaft cam may be worn out.
12. If the compression is too high, the combustion chambers are probably covered with soot. In this case, remove the cylinder head and clean the chambers.
13. When finished, install the spark plugs and connect the ignition and fuel systems.