4.3. Engine check by means of the vacuum gage
Using the vacuum gage, it is possible to receive information on a condition of the engine and to define that laying of a head of the block of cylinders is punched, the power supply system, piston rings or valves is damaged, the system of injection of fuel etc. is incorrectly adjusted. Unfortunately, indications of the vacuum gage can be interpreted incorrectly therefore these measurements should be used in a combination to other methods of check of the engine. For the correct definition are important both absolute value of indications of the vacuum gage, and speed of their change.
Versions of indications of the vacuum gage at diagnostics of malfunctions of the engine
Connect the vacuum gage to the inlet pipeline. Start and warm up the engine to normal working temperature.
Consider vacuum gage indications.
- If the engine is in a normal state, indications of the vacuum gage should be constants and make 430 ÷ 560 mm of mercury.
Low constant indications of the vacuum gage testify to laying damage between the inlet pipeline and the throttle case, damage of the vacuum hose, incorrectly established moment of ignition or incorrectly established phases of a gazoraspredeleniye.
- If indications of the vacuum gage are lower than norm on 80 ÷ 200 mm of mercury. also hesitate, that, possibly, laying of the inlet pipeline near an entrance opening is damaged or the injector is faulty.
- If indications constantly fall on 50 ÷ 100 mm of mercury. rather stable value, that, probably, valves are damaged. In this case it is necessary to measure a compression in engine cylinders (see. Section Check of kompressionny pressure).
- If indications fall, but is not regular, that, probably, gets jammed the valve or there is a failure in ignition.
- If at constant turns of idling of the indication with amplitude about 100 mm of mercury quickly fluctuate., and from an exhaust pipe there is a smoke, probably, directing plugs of valves are damaged.
- If indications quickly fluctuate at increase in turns of idling, that, possibly, laying of the inlet pipeline or laying of a head of the block of cylinders is damaged, springs of valves are weakened, valves scorched or there is a failure in ignition.
Small fluctuations about 25 mm of mercury. are usually connected with failures in ignition system.
- If indications strongly fluctuate, that, possibly, laying of a head of the block of cylinders or the cylinder is damaged.
- If the arrow slowly moves largely values, that, possibly, the system of operated ventilation of a case is littered, laying of the inlet pipeline or laying between the case of a butterfly valve and the pipeline is damaged.
Check, vacuum gage indications after sharp and complete opening of a butterfly valve and its reset are how fast restored. If the engine is in a normal state, indications fall almost to zero, then increase approximately on 130 mm of mercury. higher norms and again decrease to former values at constant turns of idling. If indications are restored slowly and pass through a maximum after butterfly valve closing, that, probably, piston rings are damaged. If there is a long delay, that, possibly, the system of release of OG is littered.