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Checking the engine by means of the vacuum gauge
Using the gauge, you can get information about the status of the motor and identify the violation of serviceability of functioning of the power system, damage to the cylinder head gasket, piston rings, valves, and so on. Unfortunately, the testimony of the gauge can easily be misinterpreted, so the analysis of measurement data must be based on the results Engine tests carried out by other methods. When checking important as the absolute values of the gauge readings and the rate of their variation. Fundamentals and arrows gauge fluctuations in the diagnosis of malfunctions of the engine  | - Connect the vacuum gauge to the intake manifold. Start the engine and warm it up to normal operating temperature.
- Consider the testimony of the gauge.
- If the engine is in normal condition, the gauge readings should be stable at 430-560 mm. Hg. Art.
- Low stable readings gauge can indicate the fact of the destruction of the gasket between the intake manifold and the throttle body, vacuum hose damage, violation of setting the ignition timing / camshaft.
- If the gauge readings are not stable (there are fluctuations of the arrow) and understated relative to the norm of 80 - 200 mm. Hg. Art., check the condition of a lining of the inlet pipeline near the inlet. There is also the probability of failure of the corresponding injector.
- Constant readings fall 50 - 100 mm Hg. Art. values are relatively stable in high probability indicates damage to the valves, - measure the compression pressure in the cylinders.
- Irregular drop readings may indicate jamming of the valve, or failure in the ignition.
- If indications quickly fluctuate with the amplitude of about 100 mm. Hg. v. at stable idle, and the output of the exhaust system is a strong smoke formation should check the valve guides.
- Rapid fluctuations in readings by increasing the idle speed may be a sign of damage to the lining of the inlet pipeline and / or the cylinder head, valves, valve springs weakening, burning plates of valves, as well as failures in the ignition.
- Minor fluctuations in the range of 25 mm Hg. Art. normally associated with failures in the ignition system.
- If the readings vary greatly, you may have a damaged cylinder head gasket or cylinder wall itself.
- Slow motion arrow over a wide range, says the system is clogged controlled crankcase ventilation (PCV), damaged intake manifold gasket or gasket between the throttle body and the pipe.
- Check how quickly restored after a sharp gauge readings and fully open throttle and return it to its original position. If the engine is in a normal state, indications fall almost to zero, and then increases by about 130 mm. Hg. Art. above the norm and again decrease to former values in stable idle. If readings are recovered slowly and pass through a maximum after closing of the throttle may be damaged piston ring. The long delay suggests a possible violation of patency of the exhaust system.
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