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4.2. Check of the engine by means of the vacuum gage

Using the vacuum gage, it is possible to obtain information on a condition of the engine and to elicit the fact of violation of serviceability of functioning of a power supply system, damage of laying of a head of cylinders, piston rings, valves and so forth. Unfortunately, indications of the vacuum gage can be easily incorrectly interpreted therefore the analysis of these measurements has to be made taking into account results of the checks of the engine which are carried out by other methods.

When checking both absolute values of indications of the vacuum gage, and speed of their change are important.

Basic provisions and fluctuations of an arrow of the vacuum gage at diagnostics of malfunctions of the engine

 PERFORMANCE ORDER

  1. Connect the vacuum gage to the inlet pipeline. Start the engine and warm up it up to the normal working temperature.
  2. Consider indications of the vacuum gage.
    • If the engine is in the normal state, indications of the vacuum gage have to be stable and make 430-560 mm Hg.
    • Low stable indications of the vacuum gage can indicate the fact of destruction of laying between the inlet pipeline and the case of a throttle, damage of a vacuum hose, violation of installation of the moments of ignitions/phases of gas distribution.
    • If indications of the vacuum gage are unstable (fluctuations of an arrow take place) and are underestimated concerning norm by 80 - 200 mm Hg, it is necessary to check a condition of laying of the inlet pipeline near an entrance opening. Also the probability of failure of the corresponding injector is not excluded.
    • Continuous fall of indications on 50 - 100 mm of mercury. rather stable value in high points by degree of probability to damage of valves, - measure compression pressure in cylinders.
    • Irregular fall of indications can speak about jamming of the valve, or failure in ignition.
    • If indications quickly fluctuate with an amplitude about 100 mm Hg at stable turns of idling, and at the exit of system of release strong smoking takes place, it is necessary to check a condition of the directing plugs of valves.
    • Bystry fluctuations of indications at increase in turns of idling, can be the evidence of damage of laying of the inlet pipeline and/or a head of cylinders, weakening of valvate springs of valves, burn-outs of plates of valves, and also failures in ignition.
    • Insignificant fluctuations in the range of 25 mm of mercury. are usually connected with failures in system of ignition.
    • If indications strongly fluctuate, perhaps, damage of laying of a head of cylinders, or walls actually of the cylinder takes place.
    • The slow movement of an arrow in the wide range of values, is said about a contamination by system of the operated ventilation of a case (PCV), damage of laying of the inlet pipeline, or laying between the case of a butterfly valve and the pipeline.
  3. Check, indications of the vacuum gage after sharp and full opening of a butterfly valve and its return to a starting position are how fast restored. If the engine is in the normal state, indications reduce almost to zero, then norms increase about 130 mm Hg above and again decrease to former values at stable turns of idling. If indications are restored slowly and pass through a maximum after closing of a butterfly valve, perhaps, piston rings are damaged. The long delay demonstrates possible violation of passability of system of release.