Compression measurement in a VAZ 2109 engine

Compression in the cylinders of the VAZ 2109 engine is a very important indicator, on which not only power depends, but also the internal state of the engine and its parts. If the car engine is new and well run-in, then it is generally accepted that the value of 13 atmospheres will be excellent compression. Of course, you should not count on such indicators if the mileage of your car is already quite large and has exceeded 100 km, but it should be borne in mind that compression of at least 000 bar is considered the minimum allowable.

Many people turn to specialized service stations to diagnose their VAZ 2109 engine for this procedure, although in fact this work can be done independently, having with you a special device called a compressometer. I bought myself such a device a few months ago, and now I measure the compression on all my machines myself. The choice fell on the device from Jonnesway, since I have been using the tool of this company for a long time and I am very satisfied with the quality. This is how it looks clearly:

So, below I will talk in detail about the procedure for carrying out the work. But first of all, you need to perform several preparatory steps:

1. It is important that the car's engine is warmed up to operating temperature.
2. Shut off the fuel line

First of all, it is necessary to shut off the entry of fuel into the combustion chamber. If you have an injection engine, this can be done by removing the fuel pump fuse and starting the engine before the remaining gasoline burns out. If it is carbureted, then we simply disconnect the hose after the fuel filter and also burn out all the fuel!

Then we disconnect all high-voltage wires from the candles and unscrew them. Then, into the first spark plug hole, we screw the compression gauge fitting, as shown in the photo:

At this moment, it is advisable to have an assistant for himself, so that he sat in the car and, with the gas pedal fully depressed, twisted the starter for several seconds, until the arrow of the device ceases to rise up the scale:

As you can see, in this case, the readings are approximately equal to about 14 atmospheres, which is an ideal indicator for a new well-run VAZ 2109 power unit.

In the rest of the cylinders, the check is carried out in the same way, and do not forget to reset the instrument readings after each measurement step. If, after checking the compression, it differs by more than 1 atmosphere, then this indicates that not everything is in order with the engine and it is necessary to look for the cause of this. Either the wear of the piston rings, or a burnout valve or improper adjustment, as well as a punctured cylinder head gasket, can cause a drop in pressure in the cylinders.