Note. Compressometers are available in two types: with clamping and threaded nozzles. The latter are screwed into the spark plug holes and provide a more reliable measurement, although their connection is somewhat more time consuming.
1. Reduced engine output, excessive oil and/or fuel consumption should be considered as signs of excessive wear on the internal components of the power unit. Measurement of compression pressure in each of the engine cylinders will help localize the problem.
2. Check the engine oil level and battery charge.
3. Warm up the engine to normal operating temperature, then shut it off.
4. Turn off the ignition system.
5. Mark and disconnect BB wires from spark plugs.
6. Thoroughly blow out candle niches (you can use a regular bicycle pump), then remove the spark plugs.
7. Move the throttle to the fully open position, - block the damper drive, or ask an assistant to keep the gas pedal fully depressed.
8. Screw the adapter of the compression gauge tightly into the spark plug hole of the first cylinder of the engine.
Attention! Try not to break the thread in the head!
9. Following the instrument manufacturers' instructions, connect a remote switch to the starter circuit.
10. Make sure the ignition key is turned to the OFF position and use the remote switch to crank the engine through at least five revolutions of the crankshaft (rotation must last at least 5 seconds). Read and record the pressure gauge reading.
11. Proceeding in a similar manner, alternately measure the compression pressure in the remaining engine cylinders.
12. Compare the measurement results with each other - they should not differ by more than 25%. So, if the maximum reading is 1034 kPa, the minimum should be at least 75% of this figure, i.e. be not lower than 779 kPa.
13. If the pressure in any of the cylinders is excessively low, pour approximately a teaspoon of engine oil into it through the candle hole and repeat the test. If the addition of oil corrects the situation, then there is excessive wear on the piston rings and/or cylinder bores. Otherwise, with a fairly high degree of probability, we can talk about burning / mechanical damage to the working chamfers of the valves or their seats (the possibility of a violation of the integrity of the cylinder head gasket is also possible). The reason for the same decrease in pressure in two adjacent cylinders is usually a breakdown of the sealing gasket bridge between these cylinders (adding oil will not improve the situation). Ingress of oil and coolant into the combustion chambers (usually accompanied by thick white or blue exhaust smoke - not to be confused with white smoke produced during engine warm-up or when the vehicle is operated in cold weather) can be regarded as another confirmation of the fact of a violation of the integrity of the gasket - check the engine oil for signs of the presence of coolant in it.