defects in components and assemblies - the key to the smooth operation of any vehicle.But if he suddenly began to lose power, or do not even run "on hot", it should take the diagnosis engine.During this test, using special equipment measure the pressure in the cylinders of the engine.This process is called compression test.Of course, not always possible to turn to professionals to the car wash.So today we'll look at how to test compression engine on their own.
On compression
Generally, this concept refers to a value of air pressure in the cylinders of the internal combustion engine at the end point of the compression stroke at the time of cranking the crankshaft.Diagnostics of the engine VAZ and many other domestic cars in the compression allows more accurately determine the specific problem in the engine.When the engine is not subjected to even partial disassembly.
Why is this value decreases over time?
reason for reducing the pressure in the cylinders of the engine could be defective element timing.But most often it is due to natural wear mechanisms piston.But be that as it may, the pressure drop significantly affects the power of the engine and the total fuel consumption.
What else can affect the compression of the engine?
general causes of change in pressure in the cylinders of a lot.Among them we should highlight the following points:
- throttle position.
- Wrong valve clearance in the drive.It should be noted that a small clearance can lead to later closing as a result of which the pressure in the cylinders is substantially reduced.It can also change the angle of the crank shaft, whereby the compression is also significantly reduced.
- motor temperature.This parameter depends upon, many engine components, in particular, the same valves.The lower the temperature, the smaller the gap.Accordingly, the pressure in the cylinder is also reduced.
- various leaks in the details, which seal the cavity combustion chamber.
Under which conditions of the engine compression is perfect?The potential for leakage of air through the various holes are minimal only when:
- cylinder will have a perfect circular shape.
- Piston rings most closely adjacent to each other.
- on the working surface of the cylinder no longitudinal risks.
- Gap castles rings close to zero.
- Plates valves maximum adjacent to the seat.
The measurement is carried out the compression of the engine?
For this purpose there is a special device.It is called Compression.At the moment, almost all of its models are equipped with special adapters for different engine models.Compression is most often used in the "home" conditions, while on professional services for that use more advanced phones - kompressografy and motor testers.
What faults can be detected using compression tester?
using this device in the home, you can manually specify a number of faults internal combustion engine.For example, if the compression is not increased, it may indicate that the valve seats being damaged through which air exits.If on the same scale, a dramatic increase in this value (e.g., at the 1st cycle compression rate is equal to three atmospheres of pressure, and further it is increased to eight), this indicates the wear of piston grooves, rings or cylinder walls.When the shutter is in the open position and the observed changes of pressure parameters, most likely on the surface of the cylinders have burrs or valves in the engine deformed.Also, it may be rings or coking and burnout of the valve piston.Well, if the data changes when the valve is closed, you should pay attention to the condition of the walls of the combustion chamber.It can develop a crack.Additionally, the change of compression in this case refers to "lag" the valves.Yet it may be burnout cylinder head gasket.
How to check the compression engine with their own hands?About devices
As we said earlier, you need to have a special device - Compression.With it we measure the level of pressure in each cylinder of the engine individually.Total compressometer are of two types:
- with threaded tip. To diagnose their screwed into the spark plug hole.
- With Pressure tip. where measurement data is held tightly after the rubber grommet into the hole of automobile spark plugs.
way, the compression in the diesel engine is measured by instruments only with threaded lugs.In addition, such compressometer not require certain skills and skill when measuring pressure.The very diagnosis of cars can be performed with an assistant, and alone.
Prepare engine for measurements
Before the measurement of compression, it is necessary to warm up the engine to operating temperature (not less than 80 degrees Celsius).Also, before going to work, check the battery charge.If it is low, be sure to charge it before diagnosis.Another special role in measuring the compression plays a bad starter.When he turns the motor with a frequency of less than 200 rpm, this car will be a diagnosis useless because of the large differences in the testimony.If all you correctly, you can safely get to work.
Guide
So, how to test compression engine with their own hands?First we need to unscrew all spark plug wires, then remove one by one the candles.Moreover, they should be spread out in such a sequence, so you can then screw in every detail in place.Many motorists are wondering: "Why do I need to unscrew all the candles?" The answer to this question is very simple.The fact that the compression test when screwed candles will not give accurate results.All figures are only approximate, inaccurate or large fluctuations.Therefore, in no case should not be unscrewed only one candle in the engine.
But back to work.As further measured engine compression is performed?After the candles for safety reasons disconnect all low voltage wires from the coils.Further, if you have a petrol engine and the pump of mechanical type, remove the fuel hose.So, we will block the flow of fuel into the cylinder.If you are an injector and the electric fuel pump, pull the relay device or take out the power cord out of all nozzles.After these manipulations, you can start measurements.
How to use Compression?First we need to install it in the end of the spark plug hole, then press the gas pedal (not yet open throttle) and the starter, so he turned the engine.So do until such time as the data on the scale compressometer not cease to grow.Then we write the data to the notebook and be sure to label the cylinder pressure at which we have just measured.Then we reset the parameters to the Compression and go to the next cylinder.Diagnosing it in the same way.
After the measured pressure on all cylinders, we collect all the items in reverse order and proceed to the analysis of the data obtained.
analyzing data
To understand how a good result given the engine, you must have a "User's Guide" for your model and type of car.There should be a standard of performance values are described specifically for this type of engine.Often, normal compression engine VAZ 2107-2170 models ranging from 9.5 to 10 atmospheres.This may be a small spread in values - up to 1 atmosphere.If the compression in your engine was about 8.5-11 atmospheres, is a great indicator.But again, in order to make a more accurate calculation, you need to have management and documentation specific to the model of the engine.
But if you received a value below 8.5 atmospheres, so there is a fault in the engine, which certainly need to be addressed.In order to identify them, you will need 10 ml of engine oil.And we have poured into the cylinder and repeat the measurement.
If the findings increased significantly and even become an order of magnitude higher than normal in subsequent measurements in the 2nd, 3rd and 4th cylinders are likely to have trouble in the plunger.This may be bedding or wear rings.To resolve this failure, you must perform a full Decarbonizer engine.But if the level of pressure in the cylinders remained the same, the problem lies in the valves - namely their poor fit.Sometimes it happens that the cause of burnout is reduced compression valves.Most often this occurs because of cracks in the piston or cylinder head gasket badly worn.At the check engine compression is completed.
How to find the exact location of breakage?
For this we need a compressor.Next you need to follow the instructions.First, we install the piston cylinder (which check) to the BMT.Next, put the car on a manual brake and turn 4th gear.After that run the compressor and pressurize the cylinder.Thus it is necessary to look carefully where it is leaking air.If you see a hiss in the next cylinders most likely happened sample cylinder head gasket.In this case, you must replace it.If such a sound was detected in the manifold, the problem lies in the intake or exhaust valve.To identify the breakdown in the cooling system of the engine, you need to unscrew the cap of the expansion tank.If faults in the antifreeze will form bubbles.
So, we figured out how to check the engine compression yourself.
